ALBERT

Beschreibung: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 196〈/p〉 〈p〉Author(s): Zhendong Zhang, Hui Qin, Yongqi Liu, Liqiang Yao, Xiang Yu, Jiantao Lu, Zhiqiang Jiang, Zhongkai Feng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As a renewable and clean energy, wind energy plays an important role in easing the increasingly serious energy crisis. However, due to the strong volatility and randomness of wind speed, large-scale integration of wind energy is limited. Therefore, obtaining reliable high-quality wind speed prediction is of great importance for the planning and application of wind energy. The purpose of this study is to develop a hybrid model for short-term wind speed forecasting and quantifying its uncertainty. In this study, Minimal Gated Memory Network is proposed to reduce the training time without significantly decreasing the prediction accuracy. Furthermore, a new hybrid method combining Quantile Regression and Minimal Gated Memory Network is proposed to predict conditional quantile of wind speed. Afterwards, Kernel Density Estimation method is used to estimate wind speed probabilistic density function according to these conditional quantiles of wind speed. In order to make the model show better performance, Maximal Information Coefficient is used to select the feature variables while Genetic Algorithm is used to obtain optimal feature combinations. Finally, the performance of the proposed model is verified by seven state-of-the-art models through four cases in Inner Mongolia, China from five aspects: point prediction accuracy, interval prediction suitability, probability prediction comprehensive performance, forecast reliability and training time. The experimental results show that the proposed model is able to obtain point prediction results with high accuracy, suitable prediction interval and probability distribution function with strong reliability in a relatively short time on the prediction problems of wind speed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419306958-ga1.jpg" width="159" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Hiral D. Shah, J.A. Bhalodia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this communication, we report the structural and electrical transport properties of (1-〈em〉x〈/em〉) La〈sub〉0.7〈/sub〉Sr〈sub〉0.3〈/sub〉Mn〈sub〉0.95〈/sub〉Co〈sub〉0.05〈/sub〉O〈sub〉3〈/sub〉 (LSMCO) + (〈em〉x〈/em〉) ZnO (〈em〉x〈/em〉 = 0%, 6%, 9%, 12%, 15% & 18%) composites. For the preparation of (1-〈em〉x〈/em〉) LSMCO + (〈em〉x〈/em〉) ZnO (〈em〉x〈/em〉 = 6%, 9%, 12%, 15% & 18%) composites, sample of LSMCO was prepared by the auto combustion technique/inexpensive modified sol-gel technique. The results of Rietveld refined XRD data show that LSMCO sample possesses a rhombohedral structure with the 〈em〉R-3c〈/em〉 space group whereas ZnO compound remains with hexagonal structure with the 〈em〉P6〈/em〉〈sub〉〈em〉3〈/em〉〈/sub〉〈em〉mc〈/em〉 space group in all the composite samples. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that no any extra unwanted phase was observed in each composite excluding the LSMCO and ZnO phases. ZnO is mostly distributed at the grain boundaries and on the surface of the LSMCO grains. Elemental presence and ratio was confirmed through the EDX analysis. The electrical resistivity of LSMCO and each composite was measured in the temperature range of 2 K–320 K at 0 Oe, 10 kOe, 50 kOe & 90 kOe magnetic field. The results indicate that the ZnO addition increases the resistivity of all the composites compare to that of pure LSMCO. The electrical resistivity explored by the theoretical model below 〈em〉T〈/em〉〈sub〉MI〈/sub〉 and fitting enlightenment for the observed behavior is transmitted here in detail.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Dezhi Yang, Weihua Liu, Dingfu Cheng, Jieshi Chen, Hao Lu, Chun Yu, Jijin Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉(Co, Cr)23C6 type carbide is a typical metallic compound in many cobalt bearing alloys, and it acts as the strengthening phase in the form of bulk eutectic carbides or precipitated carbides. In this work, first-principles calculations were carried out to investigate the electronic structure, phase stability, mechanical and magnetic properties of (Co, Cr)23C6 with different cobalt occupation. Some of the calculated values are compared with previous studies and, they are found to be in a good agreement. The method considering curvature radius is firstly used to describe the degree of anisotropy. The hardness calculated through elastic constants presents an approximate downtrend with the cobalt concentration. Analysis of the density of states (DOS), overlapped population and electron density maps, indicates that the bonds in (Co, Cr)23C6 are the mixture of covalent, ionic and metallic bonds, the interactions of 〈em〉d-d〈/em〉 orbits between metallic atoms contribute most to the hybridization mode. According to the population analysis, the reduction in hardness can attribute to the increase of metallicity and iconicity of the interacted metallic atoms. In addition, the formation of a large quantity of antibonding also plays a negative role in intrinsic hardness of (Co, Cr)23C6 when massive substitution of cobalt atom.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Morteza Alizadeh, Andisheh Shakery, Erfan Salahinejad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this research, the structure and mechanical properties of 1050 aluminum strips reinforced with E-glass fibers, processed by the cross accumulative roll bonding (CARB) process, were investigated from microscopic, hardness, tensile and peeling viewpoints. The results indicated that the incorporation of the glass fibers in the Al matrix increases strength and micro-hardness but decreases elongation. In addition, it was realized that some of these fibers are broken and changed to short fibers during the CARB process. The presence of the glass fibers strongly also reduces the bond efficiency of the Al strips, typically from 50% to 5%. To compensate this deleterious effect, it was found that at least 25% should be increased to the normal thickness reduction used in CRAB.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): J.Y. Oh, Tien M. Le, A.T. Pham, D.H. Tran, D.S. Yang, B. Kang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we investigated a correlation between superconductivity and interlayer coupling of two different alkaline (Na and K)-substituted Bi〈sub〉1·6〈/sub〉Pb〈sub〉0·4〈/sub〉Sr〈sub〉2〈/sub〉Ca〈sub〉2〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉10+δ〈/sub〉 (BSCCO) polycrystalline samples. The excess conductivity analysis by the Aslamazov-Larkin (AL) and Lawrence-Doniach (LD) theories showed that Na substitution at the Ca site induced a gradual broadening of 3D fluctuation region with increasing interlayer coupling strength, which explains a systematic increase of 〈em〉T〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉 and a decrease of normal state resistivity. On the other hand, exactly the opposite results were observed in the K-substituted samples in place of Sr. Extended x-ray absorption fine structure (EXAFS) studies revealed that substitution of Na and K generated completely different effects on the local structure around Cu atoms. It is noticeable that the Cu–O bond distance was found to decrease monotonically with the varying amounts of Na, which indicates that the CuO〈sub〉2〈/sub〉 layer is stabilized. On the while, the opposite was observed to occur with the varying amounts of K. Unlike the Cu–Ca bond which was the least affected by the substitution, the Cu–Sr bond distance increased drastically with K substitution. All these findings indicate that Na substitution at the Ca site enhances superconductivity with no loss of interlayer interaction, while K substitution at the Sr site weakens superconductivity due to the diminished interlayer interaction.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Moara M. Castro, Shima Sabbaghianrad, Pedro Henrique R. Pereira, Eric M. Mazzer, Augusta Isaac, Terence G. Langdon, Roberto B. Figueiredo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A magnesium/aluminium composite was produced by room temperature consolidation through high-pressure torsion (HPT) processing. Half-discs of the pure metals were placed side-by-side and subjected to different numbers of turns. The initially reduced interface between the phases gradually increased with increasing rotation. The composite displayed a significant ductility even after 10 turns. The distribution of hardness in the HPT-processed discs was bi-modal in the early stages of processing. As the number of turns increased and the thickness of the phases decreased there was a noticeable increase in hardness. The hardness values of the composite further increased after thermal treatment due to the formation of intermetallics within the interface between the magnesium and aluminium-rich phases.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Lipeng Xu, Fei Zhou, Jizhou Kong, Haobin Zhou, Qian Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of testing temperature on the electrochemical properties of Li(Ni〈sub〉0.6〈/sub〉Mn〈sub〉0.2〈/sub〉Co〈sub〉0.2〈/sub〉)O〈sub〉2〈/sub〉 are investigated in detail. When the testing temperature is 40 °C, the Li(Ni〈sub〉0.6〈/sub〉Mn〈sub〉0.2〈/sub〉Co〈sub〉0.2〈/sub〉)O〈sub〉2〈/sub〉 cathode material possesses the highest initial discharge capacity of 162.4 mAh·g〈sup〉−1〈/sup〉 at 0.5C rate, but their cycling stability decreases markedly. When the test temperature rises up to 60 °C, the side reaction between electrolyte and cathode material becomes serious, and the Li(Ni〈sub〉0.6〈/sub〉Mn〈sub〉0.2〈/sub〉Co〈sub〉0.2〈/sub〉)O〈sub〉2〈/sub〉 cannot work. When the testing temperature decreases, the electrochemical impedances like R〈sub〉ct〈/sub〉 values increase, and then the discharge capacity at 0 °C, −10 °C and −20 °C is only 80%, 53% and 23% of that at 25 °C. Based on the electrochemical impedance spectra at different temperatures, four kinds of equivalent circuit models are classified. The cycle and rate performance of Li(Ni〈sub〉0.6〈/sub〉Mn〈sub〉0.2〈/sub〉Co〈sub〉0.2〈/sub〉)O〈sub〉2〈/sub〉 cathode material could be improved obviously through Ti〈sub〉3〈/sub〉C〈sub〉2〈/sub〉(OH)〈sub〉2〈/sub〉 modification in an extreme environment, and especially in sub-zero environment.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Kenji Yoshii, Naoshi Ikeda〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dielectric and magnetocaloric measurements are carried out for the chromite TmCrO〈sub〉3〈/sub〉. This oxide was reported to be multiferroic below the Néel temperature (〈em〉T〈/em〉〈sub〉N〈/sub〉) of ∼125 K, likely due to a structural transformation. The dielectric response shows large dielectric constants below 300 K. However, from the analyses of loss tangent, AC conductivity and dielectric modulus, this behavior is rooted in hopping of charge carriers rather than electric dipoles, as proposed for some other chromites. No dielectric anomaly is found at 〈em〉T〈/em〉〈sub〉N〈/sub〉. The magnetocaloric effect shows that the magnetic transitions at 〈em〉T〈/em〉〈sub〉N〈/sub〉 as well as the spin reorientation temperature are of a second order. This result strongly suggests the absence of magnetostructural transition at 〈em〉T〈/em〉〈sub〉N〈/sub〉 in accord with no observation of ferroelectric transition at this temperature.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Rattiya Hongtong, Panya Thanwisai, Rattakarn Yensano, Jeffrey Nash, Sutham Srilomsak, Nonglak Meethong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Core-shell olivine-type electrospun and doped LiFePO〈sub〉4〈/sub〉/FeS/C composite fibers were synthesized via a single-step process employing an electrospinning method using LiOH·H〈sub〉2〈/sub〉O, metal sul phates, H〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉, citric acid, and polyvinylpyrrolidone (PVP) as the starting materials. Electron microscopy studies showed that the mean diameter of the core-shell composite fibers was about 280 ± 20 nm with a LiFePO〈sub〉4〈/sub〉 phase forming a core with a diameter of about 100 ± 20 nm and a carbon shell with a thickness of 80 ± 20 nm. An FeS phase was formed by a direct reduction of iron (II) sulfate (FeSO〈sub〉4〈/sub〉) that was evenly distributed within the core region of the composite fibers and further improved the electronic conductivity of the fibers. Na〈sup〉1+〈/sup〉, Mg〈sup〉2+〈/sup〉, and Al〈sup〉3+〈/sup〉 doping ions affected fiber morphology and electrochemical performance. All composite fibers showed excellent electrochemical performance. However, Al〈sup〉3+〈/sup〉 ions improved the electrochemical performance of the composite fibers to a significantly greater degree than Na〈sup〉1+〈/sup〉 and Mg〈sup〉2+〈/sup〉 doping ions, increasing the electronic and ionic conductivities of the material while maintaining their core-shell composite fiber characteristics.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Electrospun LiFePO〈sub〉4〈/sub〉/FeS/C and 5% doped 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉L〈/mi〉〈mi〉i〈/mi〉〈mi〉F〈/mi〉〈msubsup〉〈mrow〉〈mi〉e〈/mi〉〈/mrow〉〈mrow〉〈mn〉1〈/mn〉〈mo linebreak="badbreak"〉−〈/mo〉〈mrow〉〈mo stretchy="false"〉(〈/mo〉〈mi〉n〈/mi〉〈mi〉x〈/mi〉〈mo linebreak="badbreak"〉/〈/mo〉〈mn〉2〈/mn〉〈mo stretchy="false"〉)〈/mo〉〈/mrow〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈mo linebreak="badbreak"〉+〈/mo〉〈/mrow〉〈/msubsup〉〈msubsup〉〈mrow〉〈mi〉M〈/mi〉〈/mrow〉〈mrow〉〈mi〉x〈/mi〉〈/mrow〉〈mrow〉〈mi〉n〈/mi〉〈mo linebreak="badbreak"〉+〈/mo〉〈/mrow〉〈/msubsup〉〈mi〉P〈/mi〉〈msub〉〈mrow〉〈mi〉O〈/mi〉〈/mrow〉〈mrow〉〈mn〉4〈/mn〉〈/mrow〉〈/msub〉〈/mrow〉〈/math〉/FeS/C (M = Na〈sup〉1+〈/sup〉, Mg〈sup〉2+〈/sup〉, Al〈sup〉3+〈/sup〉) composites with a unique core-shell structure were synthesized via a simple single-step process to improved electrochemical properties for high performance and low cost Li-ion batteries.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324946-fx1.jpg" width="287" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): L.V.B. Diop, O. Isnard〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of Fe substitution on the structural and magnetic properties of the HoCo〈sub〉12-〈em〉x〈/em〉〈/sub〉Fe〈sub〉〈em〉x〈/em〉〈/sub〉B〈sub〉6〈/sub〉 (0 ≤ 〈em〉x〈/em〉 ≤ 2) series of intermetallic compounds have been studied. All of the compounds form in the rhombohedral SrNi〈sub〉12〈/sub〉B〈sub〉6〈/sub〉-type structure, the lattice constants increasing linearly with 〈em〉x〈/em〉. These compounds are ferrimagnets with a small transition metal magnetic moment and exhibit a spin reorientation transition. The Curie temperature decreases from 147 K for 〈em〉x〈/em〉 = 0–105 K for 〈em〉x〈/em〉 = 2. The Fe for Co substitution leads also to a progressive decrease of the spontaneous magnetization. The spin reorientation transition temperature is significantly reduced upon Fe for Co substitution whereas the compensation temperature is much less sensitive to the Fe composition.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Maxim S. Likhanov, Vladislav O. Zhupanov, Valeriy Yu Verchenko, Andrei A. Gippius, Sergei V. Zhurenko, Alexey V. Tkachev, Dina I. Fazlizhanova, David Berthebaud, Andrei V. Shevelkov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present a new Fe〈sub〉1–〈em〉x〈/em〉〈/sub〉Re〈sub〉〈em〉x〈/em〉〈/sub〉Ga〈sub〉3〈/sub〉 solid solution, in which a 5〈em〉d〈/em〉-metal––rhenium––partially substitutes for iron to the limiting composition of 〈em〉x〈/em〉 = 0.10. The crystal structure refined for the composition Fe〈sub〉0.91〈/sub〉Re〈sub〉0.09〈/sub〉Ga〈sub〉3〈/sub〉 shows the expected increase in the unit cell parameters compared to the parent FeGa〈sub〉3〈/sub〉 compound, however the M–M (M = Fe, Re) distance decreases within the M–M dumbbell, indicating an increased M–M bonding density. Therein, investigation of the local structure by means of 〈sup〉69,71〈/sup〉Ga NQR spectroscopy revealed the formation of homonuclear Fe–Fe and Re–Re dumbbells. Transport and thermoelectric properties have been investigated for the Re-substituted FeGa〈sub〉3〈/sub〉. Electrical transport measurements showed preservation of the nonmetallic conductivity of Fe〈sub〉1–〈em〉x〈/em〉〈/sub〉Re〈sub〉〈em〉x〈/em〉〈/sub〉Ga〈sub〉3〈/sub〉 despite the decrease of the valence electron concentration from 17 to 16.9 electrons per formula. At low temperatures, Fe〈sub〉1–〈em〉x〈/em〉〈/sub〉Re〈sub〉〈em〉x〈/em〉〈/sub〉Ga〈sub〉3〈/sub〉 is a 〈em〉p〈/em〉-type semiconductor with the band gap of 0.4 eV, but with increasing temperature the sign of the dominant charge carriers changes. Owing to the alloying effect, Fe〈sub〉1–〈em〉x〈/em〉〈/sub〉Re〈sub〉〈em〉x〈/em〉〈/sub〉Ga〈sub〉3〈/sub〉 displays 1.5 times lower thermal conductivity than FeGa〈sub〉3〈/sub〉, which increases at high temperatures because of the growing contribution of the electronic term.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325198-fx1.jpg" width="454" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Jiashu Zhang, Weiyao Zhao, Zhenjie Feng, Jun-Yi Ge, Jincang Zhang, Shixun Cao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the crystal growth, structure analysis and magnetic phase transitions in the single crystal Sm〈sub〉0.15〈/sub〉Dy〈sub〉0.85〈/sub〉FeO〈sub〉3〈/sub〉. The high-quality of the crystal is verified by X-ray diffraction technique. Our research reveals that: 1) the iron sublattice spin reorientation (SR) transition emerges at 25 K, and ends at 10 K; 2) the rare earth antiferromagnetic (AF) order transition happens at 2.6 K; 3) there is a special wasp-waist hysteresis loop at low temperatures. Knowledge of such phase transitions in rare earth orthoferrite system is of potential importance for applications and theoretical studies.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Yuliang Jiang, Xueyan Fu, Zidong Zhang, Wei Du, Peitao Xie, Chuanbing Cheng, Runhua Fan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon nanofibers embedded with magnetic Fe〈sub〉3〈/sub〉C nanoparticles have been synthesized using electrospinning technique, followed by one-step carbonization. By using Fe〈sub〉3〈/sub〉C/C nanofibers as filler with 10% content, the sample can achieve a minimum reflection loss (RL) of −54.94 dB with a thickness of 1.36 mm, as well as the broad effective absorption bandwidth (EAB) can reach to 4.5 GHz (13.3–17.8 GHz) at the thickness of 1.55 mm. The superior properties might be due to the synergistic effects of dielectric loss, magnetic loss, multiple scattering and reflection. This work presents a facile and promising method to produce high performance microwave absorption materials with thin thickness, light weight and strong absorption.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): E.J. Pickering, K.A. Christofidou, H.J. Stone, N.G. Jones〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to reduce the environmental impact of air travel, it is desirable that the efficiencies of gas turbine engines are increased. One way to achieve this goal is to increase the operating temperatures of the engine cores. Unfortunately for aero-engine manufacturers, the temperature capability limits of the Ni-base superalloys used currently have been reached. Hence, new alloys need to be developed that are capable of operating at significantly higher temperatures. In this article, the potential of tantalum-base superalloys is discussed and explored. A suite of alloys based on the Ta-Al-Co system was investigated. It was found that an array of fine carbide precipitates was formed in the Ta-rich matrix in a subset of the alloys, which is promising in terms of developing a strong and damage-tolerant microstructure, but that the elemental partitioning of Al out of the matrix accompanying precipitation is likely to degrade environmental resistance. Nevertheless, it is believed that the design principles described have the potential to facilitate the development of the next generation of high-temperature alloys based on systems of this type.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): C.Q. Zhou, Q.A. Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to understand the effect of Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 nanoparticles on crystallite growth kinetics of nanocrystalline Mg, the crystallite growth characteristics in a Mg−Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 composite and a pure Mg sample were comparatively investigated in this work. The crystallite growth exponents of nanocrystalline Mg in the Mg−Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 composite and pure Mg were determined as 〈em〉n〈/em〉 = 5 and 〈em〉n〈/em〉 = 4, respectively. Meanwhile, the activation energy for crystallite growth in Mg−Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 composite was calculated to be 118.8 kJ/mol, which is higher than 97.1 kJ/mol in pure nanocrystalline Mg. Further studies reveal that the rise of crystallite growth exponent and increase of activation energy in the Mg−Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 composite are primarily attributed to the pinning effect of Pr〈sub〉3〈/sub〉Al〈sub〉11〈/sub〉 nanoparticles at crystallite boundaries of Mg.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Liming Tan, Yunping Li, Wenkai Deng, Yong Liu, Feng Liu, Yan Nie, Liang Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three Ni-base powder metallurgy superalloys have been developed recently, and tensile tests at temperatures ranging from room temperature (RT) to 815 °C were conducted on them. The results conformed their excellent tensile properties, in comparison with several other existed polycrystalline superalloys. In this work, by means of microstructure characterization, thermal dynamic calculations, and theoretical modeling, different strengthening mechanisms including precipitation strengthening, grain boundary strengthening, solid solution strengthening, and Orowan strengthening, were found to contribute to the yield strength in different degrees, which would help to further enhance the tensile properties of these alloys through composition design and processing optimization thereafter.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324892-fx1.jpg" width="459" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Christopher S. Daniel, Peter D. Honniball, Luke Bradley, Michael Preuss, João Quinta da Fonseca〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The properties and performance of Zr-2.5 Nb alloys are strongly influenced by their crystallographic texture. As in similar Ti alloys, the texture evolution during hot-processing depends on the complex interactions between the α and β phases and involves deformation, annealing and phase transformation. Although the effect of temperature and deformation has been studied for extruded tube in this alloy, there is no data for texture development during rolling. There is some rolling data for Ti-64 (Ti–6Al–4V), but it is usually for just one of the phases and for a limited set of temperatures. We carried out hot-rolling trials from 700 °C–900 °C to reductions of 50%, 75% and 87.5% and found that the texture in both phases strengthens sharply before the β-transus and when both phases are present in similar amounts. At this point, the texture in α is a strong 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mn〉0002〈/mn〉〈mo〉|〈/mo〉〈mo〉|〈/mo〉〈mtext〉TD〈/mtext〉〈/mrow〉〈/math〉 and the texture in β a strong 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈mrow〉〈mo stretchy="true"〉{〈/mo〉〈mrow〉〈mn〉001〈/mn〉〈/mrow〉〈mo stretchy="true"〉}〈/mo〉〈/mrow〉〈mrow〉〈mo〉〈〈/mo〉〈mrow〉〈mn〉110〈/mn〉〈/mrow〉〈mo〉〉〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 rotated cube component. The results suggest there might be a synergistic effect between the two components, which includes dynamic phase transformation. The texture evolution towards stable α 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mrow〉〈mrow〉〈mo stretchy="true"〉{〈/mo〉〈mrow〉〈mn〉11〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉2〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉0〈/mn〉〈/mrow〉〈mo stretchy="true"〉}〈/mo〉〈/mrow〉〈mrow〉〈mo〉〈〈/mo〉〈mrow〉〈mn〉10〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉0〈/mn〉〈/mrow〉〈mo〉〉〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 or 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.svg"〉〈mrow〉〈mrow〉〈mo stretchy="true"〉{〈/mo〉〈mrow〉〈mn〉11〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉2〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉1〈/mn〉〈/mrow〉〈mo stretchy="true"〉}〈/mo〉〈/mrow〉〈mrow〉〈mo〉〈〈/mo〉〈mrow〉〈mn〉10〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉0〈/mn〉〈/mrow〉〈mo〉〉〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 crystallographic components and their final intensity depend on the starting texture. Texture was measured using electron-backscatter diffraction (EBSD) over large areas, with a β reconstruction software used to determine the high temperature β orientations. The texture development in Zr-2.5Nb appears similar to that reported for rolled Ti-64 at temperatures with equivalent phase fractions, although it is difficult to compare the two because of the lack of a titanium dataset as detailed as the one presented here.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324351-fx1.jpg" width="248" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): E.M.M. Ibrahim, M.A.A. Mohamed, H.M. Ali, Vyacheslav O. Khavrus, Silke Hampel, M.M. Wakkad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hydrothermal synthesis as a commonly bottom-up growth method has considerable advantages for manufacturing thermoelectric nanomaterials with advanced thermoelectric properties. However, the hydrothermally synthesized thermoelectric nanostructures often show a low thermoelectric performance due to their low power factor. In this work, we report on using a hydrothermal method for the growth of n-type Bi〈sub〉2-x〈/sub〉Sb〈sub〉x〈/sub〉Se〈sub〉3〈/sub〉 nanoflakes with a fixed thickness of ∼16 quintuple-layers. The controlling of the stoichiometric composition, phase purity and crystallinity of the Bi〈sub〉2-x〈/sub〉Sb〈sub〉x〈/sub〉Se〈sub〉3〈/sub〉 nanoflakes are demonstrated by the X-ray diffraction, Raman spectroscopy, and high resolution transmission electron microscopy. We further prove that adding of antimony into Bi〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 compound mostly influences the in-plane vibration mode. The optical energy gap is sharply increased as the Sb content increases. The effect of the antimony incorporation on the electrical conductivity, Seebeck coefficient and power factor of Bi〈sub〉2-x〈/sub〉Sb〈sub〉x〈/sub〉Se〈sub〉3〈/sub〉 nanoflakes is systematically investigated. The Bi〈sub〉1.92〈/sub〉Sb〈sub〉0.08〈/sub〉Se〈sub〉3〈/sub〉 sample is found to have the highest power factor ∼13.17 μW/cm.K〈sup〉2〈/sup〉 at 470 K which is much higher than those published for other various nanostructured or bulk Bi〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 compounds. The results propose a great prospect for further enhancing the thermoelectric power factor of the Bi〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 nanostructures synthesized by this hydrothermal method. Taking into consideration the progress in Bi–Se compounds, the results of this work advocate the promise of Bi–Se nanostructures towards producing high performance thermoelectric devices.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Javed Rehman, Roshan Ali, Nisar Ahmad, Xiaodong Lv, Chunlei Guo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It poses a great challenge to design anode materials with large capacity, excellent cyclic stability and high rate performance. In this paper, through first principle calculations, we computed electronic properties of monolayer WSe〈sub〉2〈/sub〉 with and without strain effects. Our results show that the electronic band gap decreases with strain percent. At 0% tensile strain the value of the band gap is 1.4 eV while at 10% tensile strain the band gap decreases to 0.7 eV. Therefore, the strain effect enhances the electronic conductivity and leads to an increase in the charge carrier transport. In addition, our predictions show that the adsorption energy increases with the strain. Finally, we computed the diffusion barrier for the migration of Li on the surface of a strain engineered WSe〈sub〉2〈/sub〉 monolayer. The lower barrier energy (0.24 eV) reveals that Li can easily overcome this barrier. Our results show that the strain-engineered WSe〈sub〉2〈/sub〉 monolayers are promising anode material for Li-ion battery.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Seyedeh Marjan Bararpour, Hamed Jamshidi Aval, Roohollah Jamaati〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉AA5083 and AA5052 alloys were utilized as consumable rod and substrate, respectively, in Friction Surfacing (FS) process and a three-dimensional finite element software known as ABAQUS was employed to anticipate the materials thermo-mechanical behavior over this procedure. At that point, in order to investigate the mechanical and microstructures characteristics of the coated samples, the experimental observations and model predictions have been implemented. The results clarified that the strain rate and temperature values are not high at the interface of the substrate and coating layer, also, we observed their maximum values in a layer nearby the upper surface of the coating in the advancing side (AS). Regardless of the irregular strain rate and temperature profiles, there are no important differences in the microstructure of the materials detected in the center of the cross-sections in the direction of advancing and retreating sides (RS). It should be noted that the grain structure is not influenced by the strain energy effect which is kept in the coating layer all through the FS procedure. Moreover, we can consider the grain structure recrystallization as a contributing factor in improving the material strength of the coating which is anticipated to be proportional to the grain size in reverse.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): Aref Alqahtani, Shahid Husain, Anand Somvanshi, Wasi Khan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Perovskite-type GdCr〈sub〉1-〈em〉x〈/em〉〈/sub〉Mn〈sub〉〈em〉x〈/em〉〈/sub〉O〈sub〉3〈/sub〉 (0.0 ≤ 〈em〉x〈/em〉 ≤ 0.4) nano-crystalline samples are synthesized using sol-gel auto combustion process. The effect of Mn-doping in GdCrO〈sub〉3〈/sub〉is investigated in term of structural, morphological, optical and thermal properties. X-ray diffraction (XRD) patterns confirm orthorhombic crystal structure of all the samples. The lattice parameters bond lengths and bond angles as obtained from Rietveld refinement analysis are found to vary systematically with Mn concentration. The crystallite sizes as calculated from the Scherrer's equation are found to decrease with Mn content. The Williamson-Hall (W–H) analysis reveals that the crystallite sizes decrease whereas lattice strain, stress, and energy density become more with the increase in Mn doping except for 〈em〉x〈/em〉 = 0.3.The particle size estimated using transmission electron microscopy (TEM) are consistent with that obtained through W–H analysis. Scanning electron microscopy (SEM) images with energy dispersive x-ray (EDX) analysis exhibit significant change in the surface morphology with Mn doping and ensure the elemental compositions of the samples. The Fourier transform infrared (FTIR) spectra of these samples confirm the formation of desired crystal structure with two main characteristic bands at 476 and 586 cm〈sup〉−1〈/sup〉. The optical band gap is found to reduce whereas Urbach energy increases with the increase in Mn concentration. The values of refractive index decrease in the ultraviolet region as a function of wavelength for all the samples and minimizes at the main absorption peak position as observed in the UV/Vis. spectra. The value of heat capacity at constant pressure (〈em〉C〈/em〉〈sub〉〈em〉p〈/em〉〈/sub〉) decreases with Mn doping except for 30% Mn concentration. Therefore, the present investigation suggests that the properties of GdCrO〈sub〉3〈/sub〉 system can be tuned with the appropriate doping of Mn for the potential applications.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Xinghua Zhu, Qingshuang Xie, Haibo Tian, Ming Zhang, Zongyan Gou, Shuai He, Peng Gu, Haihua Wu, Jitao Li, Dingyu Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Usually, ZnO thin films used in ultraviolet photodetector exhibit good photoresponse property when ultraviolet signal is strong enough. However, due to the high dark current, pure ZnO is insusceptible to weak ultraviolet signal. To address this problem, lithium-doped ZnO (LZO) thin films were prepared using the sol-gel method in this study. Results revealed that the LZO thin film doped with low concentration (2 at.%) had a dark current about 10 times lower than the pure ZnO. In addition, the ultraviolet with a low irradiance of 90 μW/cm〈sup〉2〈/sup〉 was used. According to the results of the investigations on the external quantum efficiency and responsivity, the inherent photocurrent generation ability of ZnO was not deteriorated through low concentration lithium doping. LZO thin film doped with 2 at.% exhibited a high sensitivity to weak ultraviolet signal --- the signal-to-noise ratio was enhanced by approximately 10 times compared with that of pure ZnO. This study indicates that LZO thin films with low doping concentration are promising application on weak ultraviolet signal photodetector.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Jian Lan, Weidong Xuan, Yu Han, Yongshun Li, Huaizhou Wu, Wei Shao, Chuanjun Li, Jiang Wang, Zhongming Ren〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of hot isostatic pressing on the tensile property of single crystal superalloys at elevated temperature is studied experimentally. The results show that the high temperature elongation of nickel based single crystal superalloys is obviously enhanced by hot isostatic pressing, while the yield strength is unchanged. Besides, it is found that the hot isostatic pressing causes the change of fracture surface. The enhancement of elongation and the change of fracture behavior are discussed.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Z.M. Li, X.N. Li, C.Y. Wang, Y.H. Zheng, Q.X. Yu, X.T. Cheng, N.J. Li, L.X. Bi, Q. Wang, C. Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The heat resistance of copper alloys is desirable to improve while it services at high temperature as electrically and thermally conductive components. In present paper, the strengthening pattern of nickel-based superalloys is expected to be applied in copper alloys. Here the Cu〈sub〉50〈/sub〉Ni〈sub〉37.5〈/sub〉〈em〉M〈/em〉〈sub〉12.5〈/sub〉 (〈em〉M〈/em〉 = Al, Cr, Mo) alloys were prepared by vacuum arc melting and heat-treated in the corresponding conditions to obtain three different kinds of typical microstructure. The room temperature (RT) properties (hardness and resistivity) and high temperature properties (melting point, softening temperature and variable temperature resistivity) of the three alloys are contrasted and analyzed in detail. The Cu〈sub〉50〈/sub〉Ni〈sub〉37.5〈/sub〉Al〈sub〉12.5〈/sub〉 alloy strengthened through the γ′ phase coherent precipitation shows the best conductivity and highest hardness (5.47 %IACS (International Annealed Copper Standard) and 310.1 HV). The splitting of the γ′ phase is contributing to hardening at high aging temperature. The resistivity-temperature behavior of the three alloys shows that the resistivity with rising temperature consists of the ideal lattice resistivity and the resistivity increment due to the defects. The Cu〈sub〉50〈/sub〉Ni〈sub〉37.5〈/sub〉Al〈sub〉12.5〈/sub〉 alloy has the smallest room temperature resistivity and its resistivity maintains the lowest during the whole heating process (RT-1077K). Therefore, the coherent precipitated γ′ phase is expected to improve the heat resistance of the copper alloys while maintaining its electrical conductivity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325708-fx1.jpg" width="282" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Cui-Ning Feng, Xiao-Ye Zhan, Pan Li, Xiao-Feng Guo, Dan Li, Xiu-Cheng Zheng, Guang-Ping Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Glucose-derived porous activated carbon materials (AGC-600-4 and AGC-180-〈em〉x〈/em〉) are prepared using ZnCl〈sub〉2〈/sub〉 as the etching agent via impregnation treatment and hydrothermal method followed by the calcination process. The analytic results indicate that the obtained materials exhibit higher specific surface area and superior double-layer capacitive behavior than the corresponding pristine carbon (GC-600 and GC-180) when used as electrode materials for supercapacitors. Moreover, compared with the AGC-600-4 nanosheets, the optimal AGC-180-4 microspheres have a high specific surface area of 1713 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉 and a maximum specific capacitance of 235.9 F g〈sup〉−1〈/sup〉 at a current density of 1.0 A g〈sup〉−1〈/sup〉 in the three-electrode system. Meanwhile, AGC-180-4 also exhibits better capacitive properties than AGC-600-4 in the two-electrode system, showing an excellent cyclic stability with a high energy density of 24.63 Wh kg〈sup〉−1〈/sup〉 at the power density of 949.5 W kg〈sup〉−1〈/sup〉. It is thus demonstrated that AGC-180-4 could be ideal electrode materials for supercapacitor due to its unique etched spherical structure and excellent electrochemical properties.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325903-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Ilham Bezza, Erwann Luais, Fouad Ghamouss, Mustapha Zaghrioui, François Tran-van, Joe Sakai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An 〈em〉in-situ〈/em〉 temperature-controlled Raman spectroscopy aided unique electrode fabrication technique has been developed for Li-ion battery applications, ensuring superior electrochemical quality of the multi-porous LiCoO〈sub〉2〈/sub〉 films with higher stoichiometric purity of high temperature (HT)-LiCoO〈sub〉2〈/sub〉 phase, by observing the structural changes during the fabrication process and thus confirming the transformation from the low temperature (LT)-LiCoO〈sub〉2〈/sub〉 phase. This much desired simple process is not only free of any sort of binders or carbon additives but also works at atmospheric pressure, leading to a very simple deposition technique using a homemade and inexpensive set-up. Also, the time of depositions were varied and resultant films we investigated for their electrochemical performance. The high-resolution scanning electron microscope (SEM) observation has revealed not only a μm-size porous structure but also three-dimensional cross-link with 10 nm-level pores of the material, which ensured the much-desired porosity for high-performance cathodes.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): S.C. Ram, K. Chattopadhyay, I. Chakrabarty〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Functionally graded in-situ A356-Mg〈sub〉2〈/sub〉Si composites by centrifugal casting method have been studied with varying percentage of extra Mg additions during synthesis. The coarse primary Mg〈sub〉2〈/sub〉Si particles and the Si morphology in eutectic do not yield appreciable mechanical properties. Solution treatment and artificial ageing (T6) are effective means to improve mechanical properties by refining the as-cast structure with additional formation of very fine precipitates during ageing. The microstructural evolution has been assessed by optical, scanning and transmission electron microscopy and X-ray diffraction analysis. Ageing curves are plotted with hardness versus ageing time. High temperature tensile properties are evaluated at room temperature, 150 °C and 300 °C at different layers of the graded composites and are compared between as-cast and T6 conditions. The tensile fracture mechanisms are explained from fractographs. A remarkable improvement in high temperature tensile strength at 150 °C with adequate ductility is observed in T6 condition with respect to as-cast condition.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325721-fx1.jpg" width="264" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Taiqian Mo, Zejun Chen, Boxin Li, Hongtao Huang, Weijun He, Qing Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The impact of strain path on microstructure and mechanical properties in AA1100/AA7075 laminated metal composite was investigated in present work. The results indicate that the plastic instabilities occurred in the hard layer can be inhibited effectively and the mechanical properties of the composite were improved obviously after the cross rolling (CR) process. The formation of continuous and straight interface was attributed to the difference in flow properties between the constituent layers was decreased after CR process. It is found that the strain path change during CR results in the typical rolling texture is shifted from the ideal Brass (110)〈112〉 along the 〈em〉α〈/em〉-fiber to the near ND-rotated Brass (011)〈755〉 component, promoting a better mechanical isotropy of the AA1100/AA7075 laminated metal composite. In addition, the Al/Al alloy laminated metal composite with continuous layer structure exhibits better load-bearing capacity in hard layers than the wave layer structure during deformation, which is a main reason for increasing of the strength.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 804〈/p〉 〈p〉Author(s): N. Patra, C.L. Prajapat, P.D. Babu, S. Rai, S. Kumar, S.N. Jha, D. Bhattacharyya〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Heusler alloy of Co〈sub〉2〈/sub〉FeSi (CFS) is a promising candidate for spintronics applications due to its high magnetic moment and high spin polarization. In this report two series of CFS thin films of approximate thickness of 1000 Å were prepared using Pulsed Laser Deposition (PLD) technique by two separate routes, viz., (i) by depositing at elevated substrate temperature and (ii) by depositing at room temperature followed by post-deposition annealing under vacuum. The effects of these two thermal growth processes on the structural and magnetic properties of the films have been studied in detail here. X-ray diffraction study suggests that similar to the bulk target cubic Heusler phase is maintained in the thin films prepared by both the processes, however, X-ray reflectivity study shows that the films deposited at elevated substrate temperatures have higher density and surface roughness than the other set. Co/Fe atomic ratio in the films was found to remain near stoichiometry up to high temperature in both the series of samples though atomic percentage of Si is found to be higher in the samples. Synchrotron based Extended X-ray absorption fine structure (EXAFS) measurements indicate higher 〈em〉3d-3p〈/em〉 (Co-Si) hybridization for the series of samples prepared at elevated temperature while stronger 3〈em〉d-3d〈/em〉 (Co-Fe) hybridization for the samples prepared with post deposition annealing. EXAFS study also indicated presence of Co/Fe type antisite disorder which increases with increase in the substrate temperature. Finally from detail magnetic measurements it was observed that the films prepared by post-deposition annealing process have lesser crystallinity, magnetic ordering and magneto crystalline anisotropy in comparison to the films grown with elevated substrate heating.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 805〈/p〉 〈p〉Author(s): Hao Guo, Taotao Sun, Liguo Yue, Ning Wu, Qi Li, Wenqing Yao, Wenhu Yang, Wu Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As a kind of energy storage device, supercapacitors have attracted the attention of researchers, and the development of high-performance electrode materials is also the focus of attention. In this paper, template synthesis and pyrolysis were combined to prepare high performance porous carbon electrode materials. The carbonized electrode material effectively increased the capacitance storage capacity and charge transfer rate. The results revealed that the derivative had a relatively low charge-transfer resistance and high specific capacitance of 1059 F·g〈sup〉−1〈/sup〉 at a current density of 1.0 A·g〈sup〉−1〈/sup〉 in a three-electrode system. To further exploring practical application, a device based on the derivative and hemp-activated carbon asymmetric supercapacitor was assembled in 0.1 M Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 neutral electrolyte, which exhibited an energy density of 20.35 Wh·kg〈sup〉−1〈/sup〉 at a power density of 400 W·kg〈sup〉−1〈/sup〉. Interestingly, it showed capability retention of nearly of 91.7% and columbic efficiency of 100% even after 10000 charging/discharging cycles in the neutral electrolyte.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819325691-fx1.jpg" width="365" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Nejeh Hamdaoui, Yashar Azizian-Kalandaragh, Mouadh Khlifi, Lotfi Beji〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of Cd-doping on physical properties of Ni〈sub〉0.6-〈em〉x〈/em〉〈/sub〉Cd〈sub〉〈em〉x〈/em〉〈/sub〉Mg〈sub〉0.4〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 spinel ferrite has been investigated. Scanning electron spectroscopy (SEM) confirms the formation of grain and grain boundaries in these samples and the presence of all chemical elements introduced was confirmed by EDS. The X-ray analyses indicate that all the compounds have the cubic structure with 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mi〉F〈/mi〉〈mi〉d〈/mi〉〈mrow〉〈mover accent="true"〉〈mrow〉〈mn〉3〈/mn〉〈/mrow〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈/mrow〉〈mi〉m〈/mi〉〈/mrow〉〈/math〉 space group, cell parameter increase which Cd content. A ferromagnetic state at room temperature for all compounds is detected by a magnetization measurement of hysteresis loops. We note that the saturation magnetization increases with Cd content, however, the remnant magnetization, and the corrective field decreases. DC electrical conductivity analysis shows a semiconductor behavior for all sample. In addition, non-overlapping small polaron tunneling (NSPT) and the overlapping large polaron tunneling (OLPT) are the dominants conductions mechanisms in our samples.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Beiyue Ma, Chang Su, Xinming Ren, Zhi Gao, Fan Qian, Wengang Yang, Guoqi Liu, Hongxia Li, Jingkun Yu, Qiang Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fly ash is a typical industrial solid waste that seriously affects human health and ecological balance. In order to recycle the fly ash, in this work, porous mullite ceramics were successfully fabricated with fly ash and bauxite via reaction synthesis process. Effects of firing temperature (1450–1550 °C), silicon carbide addition amount (0–15 wt%), and potash feldspar addition amount (0–16 wt%) on the mullite porous ceramics were systematically investigated. It was found that increasing the silicon carbide addition amount or raising firing temperature was favourable for improving the cold compressive strength and thermal shock resistance of the porous ceramics. Consequently, the porous ceramics with 10 wt% silicon carbide, 4–12 wt% potash feldspar had optimal overall performances. The closed porosity and cold compressive strength ranges were 14.79%–18.57% and 217.18–236.67 MPa, respectively. The thermal cycles were 7–9 times, and the thermal conductivity was reached to 2.19–2.52 W m〈sup〉−1〈/sup〉 K〈sup〉−1〈/sup〉 at 800 °C. This work provides a convenient and promising method for the utilization of fly ash.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881932362X-fx1.jpg" width="496" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Daria N. Vtyurina, Irina A. Kaurova, Galina M. Kuz'micheva, Victor B. Rybakov, Dmitry Yu. Chernyshov, Evgeny V. Khramov, Sergey V. Firstov, Vladimir N. Korchak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Promising luminescent CsCd〈em〉X〈/em〉〈sub〉3〈/sub〉 (〈em〉X〈/em〉 = Cl, Br) single crystals, both nominally-pure and doped with bismuth, have been studied comprehensively by X-ray diffraction, X-ray synchrotron radiation, and X-ray absorption spectroscopy. Crystal structure refinement shows vacancies in the Cs crystallographic site and partial substitution of Cd〈sup〉2+〈/sup〉 ions by Bi〈sup〉3+〈/sup〉 ones in both CsCdCl〈sub〉3〈/sub〉 and CsCdBr〈sub〉3〈/sub〉 (point defects Bi〈sub〉Cd〈/sub〉〈sup〉•〈/sup〉), which is consistent with the results of X-ray absorption spectroscopy. The assumed presence of Bi〈sup〉1+〈/sup〉 ions in the Cs〈sup〉1+〈/sup〉 sites of doped CsCd〈em〉X〈/em〉〈sub〉3〈/sub〉 (〈em〉X〈/em〉 = Cl, Br) crystals is not confirmed. In the photoluminescence spectra of Bi-doped CsCdCl〈sub〉3〈/sub〉 and CsCdBr〈sub〉3〈/sub〉 crystals, a single band in the near-IR spectral range with a maximum around 1000 nm is caused by point defects Bi〈sub〉Cd〈/sub〉〈sup〉•〈/sup〉. Photoluminescence spectra and decay kinetics of Bi-doped CsCd〈em〉X〈/em〉〈sub〉3〈/sub〉 (〈em〉X〈/em〉 = Cl, Br) indicate their promising use as luminescent materials.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Sung-Hsiu Huang, Cheng-Yi Tong, Tsung-Eong Hsieh, Jyh-Wei Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For the development of advanced nanoscale multilayer protective coatings, proper design of microstructure and chemical composition of carbon containing sequential transition metal nitride nanolayers is an important issue. In this work, five different nanostructured CrCN/ZrCN multilayer coatings were deposited periodically by cathodic arc evaporation. The bilayer period of the CrCN/ZrCN multilayer coatings was kept at 20 nm. The C〈sub〉2〈/sub〉H〈sub〉2〈/sub〉 gas flow ratio was adjusted from 6.3 to 20.0% for achieving CrCN/ZrCN multilayer coatings with 2.3–4.2 at.% carbon content. Nanolaminated CrCN and ZrCN nitride layers and thin amorphous carbon nitride mixed nanolayers ∼5 nm thick were obtained as the carbon content reached 4.2 at.%. It was found that the hardness and adhesion quality were strongly improved by the carbon addition to the CrCN/ZrCN multilayer coatings. An increase of 2.6–4.6 GPa in hardness was found for the CrCN/ZrCN multilayer coatings due to the balance of solution hardening effect of carbon atoms and the softening by the amorphous mixed nanolayer. An optimal combination of high hardness, 28.9 GPa, and good adhesion, 41 N of upper critical load were achieved when the carbon content was 4.2 at.% for the CrCN/ZrCN multilayer coatings.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Hanfei Zhu, Yuyao Zhao, Yingying Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Epitaxial BiFeO〈sub〉3〈/sub〉 thin films with (100), (110) and (111) orientations were grown on the SrRuO〈sub〉3〈/sub〉-buffered SrTiO〈sub〉3〈/sub〉 substrates by using an off-axis magnetron sputtering. Unlike the BiFeO〈sub〉3〈/sub〉(110) and BiFeO〈sub〉3〈/sub〉(111) thin films that exhibited a single rhombohedral phase structure, a dominant rhombohedral phase accompanying with a small amount of tetragonal phase was identified in the BiFeO〈sub〉3〈/sub〉(100) thin film. In particular, the leakage currents and ferroelectric polarizations of sputtered BiFeO〈sub〉3〈/sub〉 thin films were focused on and these films showed utterly different current density-electric field (〈em〉J〈/em〉-〈em〉E〈/em〉) behaviors whether in the positive or negative electric field. Among the three films, the ferroelectric polarization of the BiFeO〈sub〉3〈/sub〉(100) thin film presented a good frequency stability and had the maximum remnant polarization of 〈em〉P〈/em〉〈sub〉r〈/sub〉 ∼ 78 μC/cm〈sup〉2〈/sup〉 @ 10 kHz, which could be further demonstrated by pulsed polarizations of films. The distinct differences in electrical properties of orientation-engineered BiFeO〈sub〉3〈/sub〉 thin films in present case can be attributed to their different crystallographic orientations and microstructures.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324405-fx1.jpg" width="329" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Lihong Wang, Hongtao Guan, Jianqiao Hu, Qiang Huang, Chengjun Dong, Wei Qian, Yude Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Porous jute biomass carbon (PJBC) composited by Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles were successfully prepared by a chemical coprecipitation method at a low temperature of 60 °C, which is very simple to prepare a high degree of purity of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles. The structure, morphology, and microwave absorption performances of the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites were investigated in detail. Due to the porous structure and large interfaces between Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 and PJBC, the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites show excellent microwave absorption performances. The minimum reflection loss (RL) value of −39.5 dB is obtained for the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites at the frequency of 6.4 GHz. When the thickness is only 1.6 mm, an effective absorption bandwidth (RL ≤ −10 dB) for 5 GHz is achieved from 13.8 to 17.8 GHz. The excellent microwave absorption performances for the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites are rooted in enhanced impedance matching, large interfaces, ionic polarization, eddy loss, natural resonance, and multiple reflection and scattering. Consequently, considering market applications and the cost, the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composite in this work can be a promising candidate for microwave absorber.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/PJBC composites prepared by a chemical coprecipitation method at a low temperature of 60 °C exhibit the microwave absorbing performance.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881932448X-fx1.jpg" width="476" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): N.E. Dubinin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The concentration dependencies of the self-diffusion coefficients in liquid Na–K and K–Cs alloys at 〈em〉T〈/em〉 = 373 K are calculated in the framework of the linear trajectory approximation in conjunction with the square-well (SW) model treated by the mean spherical approximation in the semi-analytical representation. It is shown that this approach allows to achieve a good description of diffusion properties for liquid binary metal alloys at the same values of the SW parameters that lead to a good description of the structure and entropy for alloys under consideration.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Xiang Wu, Richu Wang, Chaoqun Peng, Yan Feng, Zhiyong Cai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Gas atomized Cu-3Ag-0.5Zr and Cu-3Ag-0.5Zr-0.4Cr-0.35Nb (wt.%) powders were compacted by hot isostatic pressing (HIP) and followed by forging. The microstructures and tensile properties at room and elevated temperatures (400 °C, 450 °C and 500 °C) were investigated. The continuous Ag precipitates (5–25 nm) and Cu〈sub〉4〈/sub〉AgZr (200–500 nm) particles are the main strengthening phases in the Cu-3Ag-0.5Zr alloy. The yield strength and ultimate tensile strength at room temperature are enhanced by 104 MPa and 83 MPa, respectively, due to the introduction of Cr〈sub〉2〈/sub〉Nb (50–80 nm) particles. Besides, the strength at elevated temperatures is also improved. For both the alloys, the discontinuous Ag precipitates near the grain boundaries result in a weak grain boundary cohesion when tested at 450 °C, leading to the lowest elongation. The Cr〈sub〉2〈/sub〉Nb and Cu〈sub〉4〈/sub〉AgZr particles are extremely stable when tested at 500 °C, which benefits to the performance enhancements at elevated temperatures.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Wenjing Zhang, Huihong Liu, Hua Ding, Hidetoshi Fujii〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The rolled Ti–15V–3Cr–3Sn–3Al (Ti-15-3) alloy (metastable 〈em〉β〈/em〉 titanium alloy) sheet with an average grain size of 44.0 μm was subjected to friction stir processing (FSP) at a tool rotation speed of 250 rpm and a tool traverse speed of 100 mm/min (250–100). Thereafter, a fine-grained (∼6.6 μm) and relatively equiaxed microstructure with a high angle grain boundary (HAGB) ratio of 74.5% was observed in the stir zone (SZ). Superplastic tensile tests were then conducted on this microstructure at the temperatures ranging from 600 °C to 800 °C and strain rates range of 1 × 10〈sup〉−4〈/sup〉-1 × 10〈sup〉−2〈/sup〉 s〈sup〉−1〈/sup〉, and an excellent low-temperature superplasticity (LTSP) with the elongation of 463% was obtained at 650 °C and 1 × 10〈sup〉−4〈/sup〉 s〈sup〉−1〈/sup〉. In addition, the microstructure in the gauge section of the tensile specimens interrupted at different engineering strains of 20%, 50%, 200%, and 463% (tensile fractured) at the optimal superplastic tensile condition of 650 °C and 1 × 10〈sup〉−4〈/sup〉 s〈sup〉−1〈/sup〉 was studied. It was found that the precipitated 〈em〉α〈/em〉 phase increased with the increasing strain, which contributed to the achievement of an enhanced LTSP by inhibiting the grain growth. Moreover, the α grains with a finer grain size of 4.4 μm was observed in the gauge section of the tensile fractured specimen and this was attributed to the occurrence of continuous dynamic recrystallization (CDRX). Therefore, the superplastic deformation mechanism of the Ti-15-3 alloy is recognized as grain boundaries sliding (GBS) accompanied with dislocation movement and CDRX at 650 °C and 1 × 10〈sup〉−4〈/sup〉 s〈sup〉−1〈/sup〉.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): G.E. Nikiforova, O.N. Kondrat'eva, A.V. Tyurin, M.A. Ryumin, V.N. Guskov, K.S. Gavrichev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lutetium orthotantalate with 〈em〉M′〈/em〉-fergusonite type structure was synthesized using a reverse coprecipitation method. Phase and chemical composition, as well as microstructure of the synthesized sample, were characterized by X-ray diffraction (XRD), μ-X-ray fluorescence and Fourier-transform infrared spectroscopies, and scanning electron microscopy. Heat capacity of 〈em〉M′〈/em〉-LuTaO〈sub〉4〈/sub〉 was first studied by adiabatic and differential scanning calorimetry (DSC) in the temperature range from 10 to 1300 K. Using a temperature dependence of heat capacity, the standard thermodynamic functions (entropy 〈em〉S〈/em〉〈sub〉m〈/sub〉〈sup〉o〈/sup〉(〈em〉T〈/em〉), enthalpy change 〈em〉H〈/em〉〈sub〉m〈/sub〉〈sup〉o〈/sup〉(〈em〉T〈/em〉)〈em〉–H〈/em〉〈sub〉m〈/sub〉〈sup〉o〈/sup〉(0) and derived Gibbs energy 〈em〉Ф〈/em〉〈sub〉m〈/sub〉〈sup〉o〈/sup〉(〈em〉T〈/em〉)) were calculated in the range of 〈em〉T〈/em〉→0–1300 K. The standard molar entropy of 〈em〉M′〈/em〉-LuTaO〈sub〉4〈/sub〉 at 298.15 K is 123.12 ± 0.50 J K〈sup〉−1〈/sup〉 mol〈sup〉−1〈/sup〉. A comparison of the experimental heat capacity values, obtained by DSC, with those calculated using the empirical Neumann-Kopp rule showed a reasonable agreement between the two sets of data only up to ≈1000 K. The high-temperature evolution of the lattice parameters for 〈em〉M′〈/em〉-LuTaO〈sub〉4〈/sub〉 was studied by high-temperature XRD (HTXRD). According to the high-temperature heat capacity study and the HTXRD measurements, there were no phase transformations up to 1300 K. Based on the HTXRD data, the linear and volume thermal expansion coefficients were obtained for the first time.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): V.I. Voronkova, E.P. Kharitonova, E.I. Orlova, N.I. Sorokina, T.A. Sorokin, A.M. Antipin, E.D. Baldin, V.V. Grebenev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Undoped and Mg-doped Nd〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉 oxymolybdate single crystals and polycrystalline samples have been prepared by flux growth and solid-state reactions. The materials have been characterized by X-ray diffraction, EDS microanalysis, X-ray structure analysis, differential scanning calorimetry, thermogravimetry, and impedance spectroscopy. The (MgO)〈sub〉〈em〉x〈/em〉〈/sub〉(Nd〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉)〈sub〉(1–〈em〉x〈/em〉)/2〈/sub〉 solid solution series has been shown to extend to 〈em〉x〈/em〉 = 0.20. Doping of Nd〈sub〉2〈/sub〉MoO〈sub〉6〈/sub〉 single crystals with Mg leads to splitting of the Mo, Nd1, and O2 sites. A structural model in which the Mg atoms partially substitute for Mo atoms and reside near the Mo site, 0.28 Å from it, ensures the best agreement with the observed diffraction pattern. The conductivity of the undoped and doped polycrystalline samples approaches 10〈sup〉−4〈/sup〉 S/cm at 800 °C and is assumed to have an anionic nature.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324764-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Chaocheng Liu, Xucai Kan, Xiansong Liu, Shuangjiu Feng, Jiyu Hu, Wei Wang, Khalid Mehmood Ur Rehman, Mudssir Shezad〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Conventional permanent hexagonal ferrites may prohibit the soft magnetic properties through the effort of doping behavior. A typical case of this magnetic conversion is Co–Ti doped M-type strontium hexaferrites. On the basis of this system, we developed a novel foundation of La doped CoTi-strontium hexaferrites in present work and a promising result were obtained. Polycrystalline Sr〈sub〉1-〈em〉x〈/em〉〈/sub〉La〈sub〉〈em〉x〈/em〉〈/sub〉Fe〈sub〉10〈/sub〉CoTiO〈sub〉19〈/sub〉 (〈em〉x〈/em〉 = 0.00–0.10) hexaferrites present the admirable characteristics as general soft ferrites (high permeability 〈em〉μ〈/em〉, low core loss 〈em〉P〈/em〉〈sub〉cv〈/sub〉), and retain the properties of permanent ferrites simultaneously. This extraordinary performance exhibit more appropriate candidate for multilayer inductors contrast to normal soft magnetic materials. Meanwhile, we presented a series of measurement results to investigate the morphology and texture of the sample, which revealed the internal structural feature systematically.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Magnetoplumbite crystal structure and spin directions of 2〈em〉a〈/em〉 and 4〈em〉f〈/em〉〈sub〉2〈/sub〉 sites for M-type strontium hexaferrites.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324235-fx1.jpg" width="278" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 196〈/p〉 〈p〉Author(s): Homa Hosseinzadeh-Bandbafha, Esmail Khalife, Meisam Tabatabaei, Mortaza Aghbashlo, Majid Khanali, Pouya Mohammadi, Taha Roodbar Shojaei, Salman Soltanian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biodiesel utilization is associated with reduced calorific value and increased nitrogen oxides emissions. Hence, various strategies are implemented to address these challenges such as water addition into diesel/biodiesel fuel blends. In line with that, this study was undertaken to explore the effect of water (3 wt.%) and aqueous carbon nanoparticles (38, 75, and 150 µM), as a novel fuel nanoadditive, on combustion and exhaust emissions of a diesel engine at a fixed engine speed of 1000 rev/min under four different engine loads ranging from 25% to 100% of full load conditions. Overall, the engine performance characteristics were improved by incorporating the aqueous carbon nanoparticles. In particular, the incorporation of carbon nanoparticles into water-emulsified biodiesel/diesel blends generally enhanced brake power and thermal efficiency while lowering specific fuel consumption. The most appealing performance features were observed for the emulsified fuel blend containing 38 µM carbon nanoparticles which increased brake power and brake thermal efficiency by 1.07 kW and 11.58% at full load operation, respectively, while it led to decreased brake specific fuel consumption by about 107.3 g/kWh. The addition of carbon nanoparticles to the water-emulsified fuel blends adversely affected unburned hydrocarbons and carbon monoxide emissions at full load conditions owing to an increase in carbon content of the fuel blends but it lowered nitrogen oxides emissions. The addition of water deteriorated the economic features of the fuel blend (i.e., the cost per kWh of power generated). However, carbon nanoparticles addition into the water-emulsified fuel blend partially neutralized the adverse economic effects of water due to its positive impacts on thermal efficiency. Overall, water-emulsified diesel/biodiesel containing 38 µM carbon nanoparticles could be regarded as the most promising emulsion fuel in terms of engine performance characteristics, nitrogen oxides emissions, as well as fuel economy.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Min-Su Lee, Yong-Taek Hyun, Tea-Sung Jun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We have performed macroscopic tensile and nanoindentation tests to investigate the effect of oxygen content on the global and local strain rate sensitivity of grades 1, 2 and 4 commercially pure titanium (CP–Ti). Electron backscatter diffraction (EBSD) was used to characterise the crystallographic texture of target samples and orientation of target grains. Slip activities were anticipated by Schmid factor analysis, indicating the relative incidence of 〈a〉 type prismatic and basal slips in the macroscopic region, and similarity of potential local deformation between comparative grain orientations. Further slip trace analysis around the residual impressions showed similar slip activity in equivalent orientations regardless of oxygen content. Global and local strain rate sensitivity were evaluated with respect to the influence of texture and grain orientations, respectively. Significant oxygen-dependent rate sensitivity is observed such that the rate sensitivity is inverse to the oxygen content and this effect is agreed on at both macro- and microscopic levels. These findings are potentially important for understanding the influence of oxygen content on the dwell fatigue of Ti alloys and correlating the intrinsic mechanism at the microscopic level to the macroscopic deformation behaviours.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819324107-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Y. Al-Hadeethi, S.A. Tijani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nuclear medicine makes use of different gamma emitting radioactive sources which necessitates a reliable way of reducing unnecessary exposure of nuclear medicine personnel and the general public in the vicinity of these radioactive sources. Radiation shielding is one of the major ways through which the medical personnel and the public are protected from the harmful effects of ionizing radiation. A material that combines transparency, non-toxicity and radiation shielding ability is of high interest presently in the medical environment. This work aims to determine the suitability of lead-free transparent 50BaO-(50-x)borosilicate-xBi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 glass system for radiation shielding purposes at diagnostic nuclear medicine energies and to compare its properties with that of transparent lead glass and ordinary concrete. The results of this work show that while all the glass samples show comparable shielding properties with the lead glass, glass sample G5 is the best lead glass substitute. All the studied glasses are lighter than lead glass and showed better shielding properties than ordinary concrete.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Liang Zheng, Wenjie Zhang, Qi Wang, Hong Zhang, Zhou Yu, Cuihua Cheng, Yong Zhang, Ming Lei, Yong Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉MgB〈sub〉2〈/sub〉 bulks with NaCl doping amount ranging from 0–30 at% have been prepared by hot pressed sintering process. With the increase of NaCl doping amount, the 〈em〉c〈/em〉 axis lattice parameter of MgB〈sub〉2〈/sub〉 monotonously increases, indicating the substitution of Mg atoms by larger Na atoms. Meanwhile, the intensity of diffraction peaks of both NaCl and impurity phase of MgO increases. More compact morphology was found in the NaCl doped MgB〈sub〉2〈/sub〉 samples. The critical transition temperature (〈em〉T〈/em〉〈sub〉c〈/sub〉) decreases from 38.2 K to 36.8 K with the increase of NaCl doping amount from 0 to 30 at%, and the corresponding transition width of 〈em〉T〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉 (Δ〈em〉T〈/em〉〈sub〉c〈/sub〉) increases from 0.5 K to 1.8 K. When the doping amount of NaCl is not exceeding 10 at%, the 〈em〉J〈/em〉〈sub〉c〈/sub〉 value is about 10〈sup〉6〈/sup〉 A/cm〈sup〉2〈/sup〉 at 4.2 K, 3 T, and 5 × 10〈sup〉5〈/sup〉 A/cm〈sup〉2〈/sup〉 at 10 K, 3T. 〈em〉J〈/em〉〈sub〉c〈/sub〉 performance of the 5 at% NaCl doped MgB〈sub〉2〈/sub〉 sample (NC05) reaches 6.8 × 10〈sup〉5〈/sup〉 A/cm〈sup〉2〈/sup〉 at 20 K, 2T, which improves approximately 20% compared to the pure one, attributing to the better grain connectivity of MgB〈sub〉2〈/sub〉 and enhancement of flux pinning force by NaCl doping.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 803〈/p〉 〈p〉Author(s): Yu Wang, Chao Fang, Xiang Li, Zhou Peng Li, Bin Hong Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉LaB〈sub〉6〈/sub〉 is a unique plasmonic material, for which the localized surface plasmon resonance (LSPR) absorption band intrinsically lies in the near infrared (NIR) region. In this work, we synthesized spherical LaB〈sub〉6〈/sub〉 nanoparticles with a tunable size within 50–200 nm. The optical properties of these LaB〈sub〉6〈/sub〉 nanospheres were found to be sensitive to the thickness of surface oxide layer that was formed during the synthesis, purification and dispersion processes. In order to enhance the stability of LaB〈sub〉6〈/sub〉 nanoparticles in aqueous environment, LaB〈sub〉6〈/sub〉@SiO〈sub〉2〈/sub〉 with a core-shell structure was successfully prepared. Both LaB〈sub〉6〈/sub〉 and LaB〈sub〉6〈/sub〉@SiO〈sub〉2〈/sub〉 demonstrated low cytotoxity in biomedical tests when their concentrations were limited to 0.2 mg mL〈sup〉−1〈/sup〉. The in vitro photothermal therapy experiment showed that 4T1 cancer cells were eventually apoptotic after being exposed to a 980 nm laser for 5 min at a considerably low power density of 0.82 W cm〈sup〉−2〈/sup〉 and a low dose of 0.1 mg mL〈sup〉−1〈/sup〉 for LaB〈sub〉6〈/sub〉@SiO〈sub〉2〈/sub〉. The results suggest that these LaB〈sub〉6〈/sub〉 nanospheres are viable photothermal agents for biomedical applications.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 30 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 811〈/p〉 〈p〉Author(s): Miqi Wang, Zehua Zhou, Qijie Wang, Zehua Wang, Xin Zhang, Yuying Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉FeCrMoCBY amorphous coating with a high volume fraction of amorphous phase (90%) was prepared on Q235 steel by atmospheric plasma spraying. Influence of passivation potential on the corrosion resistance of passive films on the coating surface was estimated by electrochemical measurements, capacitance analysis, AFM and XPS technique. The results revealed that increasing potential promoted the growth of a more compact and thicker film due to the formation of more bounded water and oxides. Reduction in hydroxides further decreased point defects density significantly in the passive layer when passivated at a higher potential. A low diffusivity (1.67 × 10〈sup〉−15〈/sup〉 cm〈sup〉2〈/sup〉 s〈sup〉−1〈/sup〉) corresponding to point defects could suppress both the growth and degradation processes of passive film in chloride containing electrolyte, and thus enhance the film resistance to local thinning.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Ahmed Gamal El-Shamy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel conductive PVA/CQDs nanocomposite films were synthesized through the casting technique for the electromagnetic (EM) wave protection at microwave band. The surface morphology, thermal and mechanical properties were briefly studied. The SEM micrograph showed an excellent distribution, dispersion and a high adhesion property of the CQDs in the PVA chains. Also, DSC analysis showed an increase in the〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mtext〉glass〈/mtext〉〈mspace width="0.25em"〉〈/mspace〉〈mtext〉temperature〈/mtext〉〈mspace width="0.25em"〉〈/mspace〉〈mrow〉〈mo stretchy="true"〉(〈/mo〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi〉g〈/mi〉〈mi〉l〈/mi〉〈mi〉a〈/mi〉〈mi〉s〈/mi〉〈mi〉s〈/mi〉〈/mrow〉〈/msub〉〈mo stretchy="true"〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉 from 83.2 °C for fresh PVA to 95.4 °C for 8 wt% of CQD and the increase in melting temperature from 215 °C for fresh PVA to 227.7 °C for the same CQDs concentration. It was found that Young's modulus is directly proportional to CQD nano-particles concentration in the nano-composites from 0.14 GPa for fresh PVA to 4.48 GPa for 8 wt% of CQDs. It was found that the strength at break increases, but the elongation declines with the increase of CQDs nano-particles. The EM shielding effectiveness (SE) of (PVA/CQDs) nanocomposite is measured in the microwave frequency range, and it is found around 36.8 dB with the CQDs concentration (8 wt%). Finally, the PVA/CQDs nano-composite is of promising potential applications in electronics and microwave devices at an affordable cost.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819331846-fx1.jpg" width="148" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds〈/p〉 〈p〉Author(s): A. Rajabi, A.R. Mashreghi, S. Hasani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, non-isothermal kinetic analysis of high temperature oxidation of Ti–6Al–4V alloy by thermogravimetric analysis (TGA) at heating rates of 10, 15, and 20 °C/min up to 1550 °C in air atmosphere was studied. The results revealed that the formed oxide layer consists of several different parts; an inner part of TiO〈sub〉2〈/sub〉, an outer part of TiVO〈sub〉4〈/sub〉, and an intermediate part of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. Also, the thickness of oxide layer increased by an increase in the maximum heating temperature, while its density decreased by formation of the pores and cracks in higher maximum temperature due to the mismatch between the thermal expansion coefficient of the oxide layer and the substrate. This mismatch led to formation of large stresses in the oxide layer at high temperatures (≥1000 °C) and thereby isolation of the oxide layer during cooling. The microhardness profiles shift to higher microhardness values by an increase in the maximum temperature due to the increasing of oxygen solubility in the substrate. On the other hand, the kinetic results performed by isoconversional Starink, KAS, FWO, Tang, and Friedman methods in combination with the invariant kinetic parameters (IKP) method and fitting model estimated the activation energy (〈em〉E〈/em〉) and pre-exponential factor (ln〈em〉A〈/em〉) of the oxidation process equal to 205–235 kJ/mol and 12-13 min〈sup〉−1〈/sup〉, respectively. Furthermore, it was approved that this reaction is controlled by a diffusion control model (D1 model).〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Yuejun Chen, Shizhen Zhu, Yanqi Ji, Zhuang Ma, Hengyong Wei〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to avoid infrared emissivity deterioration of MoSi〈sub〉2〈/sub〉 particles result from its high-temperature oxidation, a satisfactory electrostatic self-assembly process was presented to synthesize MoSi〈sub〉2〈/sub〉@SiO〈sub〉2〈/sub〉 particles. A thermally stable and transmitting infrared SiO〈sub〉2〈/sub〉 shell was formed with tetraethyl orthosilicate (TEOS) as a precursor and tetrabutyl ammonium bromide (TBAB) as an electrostatic adsorbent after heat treatment at 1200 °C. The oxidation resistance, composition, micro-morphology and infrared emissivity of MoSi〈sub〉2〈/sub〉@SiO〈sub〉2〈/sub〉 were studied using thermogravimetric analysis, X-ray diffraction, energy disperse spectroscopy, scanning electron microscopy, and ultraviolet–visible near-IR spectrophotometer. The results demonstrated that MoSi〈sub〉2〈/sub〉 particle was thoroughly encapsulated by a SiO〈sub〉2〈/sub〉 glass shell, consequently, it exhibited great oxidation resistance compared with that of unencapsulated. More importantly, the emissivity of MoSi〈sub〉2〈/sub〉@SiO〈sub〉2〈/sub〉 particles had no obvious recession due to the intact encapsulation with TBAB. In addition, the electrostatic self-assembly mechanism of core-shell (MoSi〈sub〉2〈/sub〉@SiO〈sub〉2〈/sub〉) particles was discussed.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Jingui Zong, Fei Wang, Guannan Liu, Mingshu Zhao, Sen Yang, Xiaoping Song〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Molybdenum disulfide (MoS〈sub〉2〈/sub〉), has aroused people's much research interest as an anode candidate for next generation of Li-ion batteries because of special layered structure and high theoretical capacity. However, MoS〈sub〉2〈/sub〉 suffers from a poor cycling stability and an inferior rate capability upon charge/discharge processes. So we have successfully synthesized a more stable expanded nanocomposite with superior electrical conductivity by intercalating moderate amorphous carbon between two adjacent S–Mo–S interlayer via a simple method which exhibits excellent lithium storage performance with high capacity (858.9 mA h g〈sup〉−1〈/sup〉 at 1 A g〈sup〉−1〈/sup〉 for 1000 cycles), and superior rate capability (518 mA h g〈sup〉−1〈/sup〉 at 4 A g〈sup〉−1〈/sup〉). This superior electrochemical performance is attributed to the special structure (few layers, 2H phase, expanded interlayer spacing, amorphous carbon between S–Mo–S layers, C–O–Mo bond in the layer), small size and evenly distributed MoS〈sub〉2〈/sub〉 nanosheets. Besides, we study the 2H-1T phase transformation mechanism by controlling the ratio of ethylene glycol to water and O–C〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/dbnd"〉O bond plays an important role in promoting 2H-1T phase transformation.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Qinjiang He, Renli Fu, Xiufeng Song, Haitao Zhu, Xinqing Su, Chaoqun You〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, Ce〈sup〉3+〈/sup〉 and Ce〈sup〉3+〈/sup〉/Dy〈sup〉3+〈/sup〉 co-doped Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉 phosphors have been designed and synthesized via a facile citrate-based sol-gel technique, and their structural, photoluminescence properties and energy transfer phenomenon were investigated comprehensively. The XRD analysis indicated that pure Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉 phase can be synthesized at low temperature (1000 °C) for merely 2 h. The photoluminescence spectra showed the dominant emission of Ce〈sup〉3+〈/sup〉 singly doped phosphors is located in the blue region even at low Ce〈sup〉3+〈/sup〉 doping level, which indeed favors the energy transfer from Ce〈sup〉3+〈/sup〉 to other luminescent centers. When Dy〈sup〉3+〈/sup〉 is co-doped into Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉:Ce〈sup〉3+〈/sup〉 phosphors, the remarkable sensitizing effect of Ce〈sup〉3+〈/sup〉 on Dy〈sup〉3+〈/sup〉 is validated by comparatively analyzing the excitation, emission spectra and average lifetimes of the series of samples. Through the concentration quenching theory, the critical distance between Ce〈sup〉3+〈/sup〉 and Dy〈sup〉3+〈/sup〉 is calculated to be 13.50 Å. Furthermore, the energy transfer mechanism between them is most likely ascribed to electric dipole-dipole interaction. In virtue of the variation of the emission intensities of Ce〈sup〉3+〈/sup〉 and Dy〈sup〉3+〈/sup〉, the emitting colors of Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉:Ce〈sup〉3+〈/sup〉, Dy〈sup〉3+〈/sup〉 phosphors can realize tunable luminescence from deep blue to bluish-white region through controlling the Dy〈sup〉3+〈/sup〉 content. Based on these analysis, Ca〈sub〉3〈/sub〉Al〈sub〉2〈/sub〉O〈sub〉6〈/sub〉:Ce〈sup〉3+〈/sup〉, Dy〈sup〉3+〈/sup〉 phosphors could potentially be applied as a single-phase color-tunable phosphors pumped by near-ultraviolet (n-UV) radiation.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Zhaohui Ma, Jiandong Zhang, Guoqing Yan, Hai Liu, Jingcun Huang, Lijun Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Thermodynamic properties of zirconium-oxygen (Zr–O) solid solution and its deoxidation by calcium in CaCl〈sub〉2〈/sub〉 molten salt were studied using a chemical equilibration technique. In the temperature range from 1173 to 1373 K, the equilibrium oxygen contents in Zr were measured experimentally under coexistence of Ca and CaO in CaCl〈sub〉2〈/sub〉 molten salt. The oxygen content in Zr was reduced from about 800 ppm to a minimum of less than 100 ppm. Then 〈em〉a〈/em〉〈sub〉CaO〈/sub〉 sensor — niobium-oxygen (Nb–O) solid solution was employed to equilibrate with Zr–O solid solution to determine the oxygen activity coefficient in Zr–O solid solution. Zr and Nb specimens were submerged in Ca-saturated CaCl〈sub〉2〈/sub〉 molten salt containing different amounts of CaO. CaCl〈sub〉2〈/sub〉 melt was used for a homogeneous reaction and composition. The experimental results shown that Henry's law held and the activity coefficient of oxygen was constant within the concentration range of this study. Based on the result, the standard formation Gibbs free energy of Zr–O solid solution was obtained as a function of temperature:〈span〉〈span〉1/2O〈sub〉2〈/sub〉 (g) = O (in Zr)〈/span〉〈/span〉〈span〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si17.svg"〉〈mrow〉〈mi〉Δ〈/mi〉〈msubsup〉〈mi〉G〈/mi〉〈mrow〉〈mi〉Z〈/mi〉〈mi〉r〈/mi〉〈mo linebreak="badbreak"〉−〈/mo〉〈mi〉O〈/mi〉〈/mrow〉〈mi〉θ〈/mi〉〈/msubsup〉〈mo linebreak="badbreak"〉=〈/mo〉〈mo linebreak="goodbreak"〉−〈/mo〉〈mn〉543577〈/mn〉〈mo linebreak="goodbreak"〉+〈/mo〉〈mn〉64〈/mn〉〈mtext〉.〈/mtext〉〈mn〉3〈/mn〉〈mi mathvariant="italic"〉T〈/mi〉〈mrow〉〈mo〉(〈/mo〉〈mtext〉1173−1373K〈/mtext〉〈mo〉)〈/mo〉〈/mrow〉〈/mrow〉〈/math〉〈/span〉〈/p〉 〈p〉The 〈em〉p-t-x〈/em〉 relationship of the deoxidation system was obtained simultaneously, which make the deoxidation limit and variation trend of oxygen content in Zr–O solid solution predictable and controllable under different conditions. Oxygen distribution coefficient between Zr–O solid solution and Nb–O solid solution was found in agreement with the theoretical value and independent of oxygen potential of the system.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Liang Ma, Shu-Shen Lyu, Yao Dai, Xian-Yinan Pei, Dong-Chuan Mo, Yuan-Xiang Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transition metal oxide/reduced graphene oxide (TMO/RGO) composites have been explored for development as anode materials for lithium-ion batteries (LIBs); TMOs have high theoretical capacities, and the oxidation degrees of RGO sheets can directly affect the lithium storage performance of TMO/RGO composites. In this work, several NiO/reduced graphene oxide composites (NiO/RGO) are prepared based on oxidation degrees of graphite oxide sheets (GOs) through an ultrasonic agitation method. These composites are then explored as anodes for LIBs. Results show that the reversible capacity of NiO/RGO composites increases gradually to 1046 mA h/g and then declines to 956 mA h/g after 50 cycles at 100 mA/g. The variation rule of lithium storage properties of NiO/RGO samples can be attributed to the surface functional groups of RGO sheets, which can affect interfacial interaction between NiO and RGO sheets due to the different oxidation degrees of GO. Different RGO sheets also show distinct abilities to hinder NiO pulverisation and promote lithium-ion/electron diffusion during repeated charge and discharge processes.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 20 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds〈/p〉 〈p〉Author(s): Kaixuan Chen, Shiwei Pan, Xiaohua Chen, Zidong Wang, Rolf Sandström〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructure evolution in the as-cast pure Cu and Cu-(1.0–3.0)Fe-0.5Co and Cu-1.5Fe-0.1Sn (wt. %) alloys was characterised in the previous work. Herein, the plastic deformation characteristics were examined by uniaxial tensile tests at room temperature. Along with the microstructure evolution, the yield strength increased with increasing Fe content and reached a peak value at 1.5 wt % Fe, but thereafter decreased with the further addition of Fe in the Cu–Fe–Co alloys. Nevertheless, the tensile strength and elongation synchronously improve with increasing Fe content. In particular, the Cu-1.5Fe-0.1Sn alloy achieved the optimal strength–ductility combination. In terms of the strengthening mechanism, the (Fe, Co)- or (Fe, Sn)-doped copper encouraged impediment, trapping, and storage of dislocations by the iron-rich nanoparticles and grain boundaries, which enhanced the strength and sustained the work hardening and elongation. The evolution of mechanical properties under an alloying effect was quantitatively described by the strengthening models. The results indicate that the optimum balance between strength and ductility was achieved by designing a microstructure containing fine grains, intragranular smaller spherical nanoparticles, and a minor solute element with higher misfit and higher growth restriction effect. The necessities for engineering a microstructure to achieve simultaneously strong and ductile bulk metals were discussed.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819331500-fx1.jpg" width="443" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Natalia Pawlik, Barbara Szpikowska-Sroka, Tomasz Goryczka, Wojciech A. Pisarski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present paper, the nanocrystalline transparent oxyfluoride SrF〈sub〉2〈/sub〉:Eu〈sup〉3+〈/sup〉 glass-ceramic materials (nGCs) were synthesized via a low-temperature sol-gel method, in which trifluoroacetic acid (TFA) was used as a fluorination reagent. The thermal degradation of precursor xerogels was examined by TG/DSC analysis and the formation of SrF〈sub〉2〈/sub〉 nanocrystals inside silicate xerogel host was proved by XRD measurements. Additionally, to verify the structural changes within silicate network during ceramization process, the IR-ATR measurements were also carried out. The optical properties of Eu〈sup〉3+〈/sup〉 ions in precursor xerogels and fabricated nGCs were investigated based on photoluminescence excitation (PLE: λ〈sub〉em〈/sub〉 = 611 nm) and emission (PL: λ〈sub〉exc〈/sub〉 = 393 nm) spectra as well as luminescence decay analysis of the 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 excited level. It was observed, that for precursor silica xerogels the electric-dipole transition (ED) 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 → 〈sup〉7〈/sup〉F〈sub〉2〈/sub〉 was dominant, meanwhile the magnetic-dipole transition (MD) 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 → 〈sup〉7〈/sup〉F〈sub〉1〈/sub〉 had the greatest intensity for SrF〈sub〉2〈/sub〉:Eu〈sup〉3+〈/sup〉 nGCs. Thus, the R/O-ratio (R/O = I(〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 → 〈sup〉7〈/sup〉F〈sub〉2〈/sub〉)/I(〈sup〉5〈/sup〉D〈sub〉0〈/sub〉 → 〈sup〉7〈/sup〉F〈sub〉1〈/sub〉)) was calculated to estimate the symmetry in the local framework around Eu〈sup〉3+〈/sup〉 ions. Moreover, the reddish-orange photoluminescence is long-lived (about 30-fold longer) for SrF〈sub〉2〈/sub〉:Eu〈sup〉3+〈/sup〉 nGCs compared with xerogels. The changes in emission spectra as well as double-exponential character of luminescence decay curves recorded for obtained nGCs indicated the successful migration of optically active Eu〈sup〉3+〈/sup〉 ions from amorphous silica framework to low phonon energy SrF〈sub〉2〈/sub〉 nanocrystal phase.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 21 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds〈/p〉 〈p〉Author(s): Ping Song, Wen-bin Li, Yu Zheng, Zhong-wei Guan, Xiao-ming Wang, Wen-xu Xu, Peng Ge〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The compressive and tensile stress–strain relationship and fracture behavior of a new low-cost titanium alloy Ti–5Al–3V–2Cr–2Fe (Ti–5322) at 286–573 K, a strain rate of 0.0001–4300 s〈sup〉−1〈/sup〉 and a stress triaxiality of 0.43–1.6 were studied. Based on the experimental data, the flow and fracture behavior of Ti–5322 was established based on the Johnson–Cook (J–C) equation. Ballistic impact tests were used to study the ballistic performance of a 7-mm-thick Ti–5322 target and the accuracy of the constitutive model was verified from the ballistic test results. The experimental results showed that the yield strength and strain rate of the Ti–5322 were related logarithmically. As the strain rate increased, the rate-strengthening behavior of the material weakened gradually. The material had an obvious thermal-softening behavior and the yield strength decreased linearly with an increase in deformation temperature. The stress triaxiality and strain rate had a significant effect on the fracture behavior of Ti–5322. The material fracture strain decreased with the stress triaxiality and an increase in strain rate. The J–C constitutive model was a good predictor for the ultimate penetration velocity of the Ti–5322 target and the velocity decay of fragments during penetration. The ballistic limit velocity of the 10-mm-diameter tungsten-alloy ball to the 7-mm-thick Ti–5322 target at 0° and 30° was 416.0 m/s and 484.8 m/s, respectively.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Dongqing Liu, Yimin Yin, Haifeng Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transient memristor is highly desirable for secure memory system and secure neuromorphic computing. Here, a transient memristor with the MgO thin film as resistive dielectric material and the Ni as electrode material is reported. The memristor shows reversible and nonvolatile bipolar resistive switching performance, narrow distribution of low resistance state (LRS) and high resistance state (HRS), uniform switching voltages and stable retention at room temperature. It is indicated that the resistive switching mechanism of the memristor is conductive filament in LRS and space charge limiting current in HRS. In addition, the memristor can be failed after immersed in deionized water for 5 min due to the film damage resulting from large frizzle and the dissolution of Ni and MgO film. The prepared memristor has potential for secure memory system application.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Lei Zhang, Shan Ji, Rongfang Wang, Dan J.L. Brett, Hui Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A flexible cathode with highly electrochemical performance for bendable supercapacitors have been achieved by electrochemical depositing hierarchical nanostructured Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉/Ni(OH)〈sub〉2〈/sub〉 compounds on the surface of commercial conductive textile. The morphology and physical properties of as-prepared electrode are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS). Based on its unique nanostructure, the obtained flexible Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉/Ni(OH)〈sub〉2〈/sub〉 electrode exhibits a highly electrochemical capacitance of 1800 F g〈sup〉−1〈/sup〉 at 3 mA cm〈sup〉−2〈/sup〉 with good rate capability, excellent stability and bendability. Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉/Ni(OH)〈sub〉2〈/sub〉 electrode as cathode is assembled with active carbon as anode and PVA/KOH as electrolyte into an asymmetric capacitor to evaluate its performance in a real supercapacitor. The obtained supercapacitor cell delivers a high energy density of 0.49 mWh cm〈sup〉−2〈/sup〉 at 3.54 mW cm〈sup〉−2〈/sup〉 and maintains the energy density at 0.38 Wh cm〈sup〉−2〈/sup〉 when power density increases to 21.53 mW cm〈sup〉−2〈/sup〉. When the assembled cells are connected in series, these connected cells can work safely and properly at a much higher voltage window due to their good stability and consistency. Considering its low-cost, facile fabrication and highly electrochemical performance, the obtained Ni〈sub〉3〈/sub〉S〈sub〉2〈/sub〉/Ni(OH)〈sub〉2〈/sub〉 electrode is a promising flexible material.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881933110X-fx1.jpg" width="255" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Runchen Jia, Weidong Zeng, Shengtong He, Xiongxiong Gao, Jianwei Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fracture toughness and fracture mechanism of Ti60 alloy with duplex microstructure under different temperature conditions were investigated in the present work. The experimental result shows that the fracture toughness of CT samples increases from the room temperature (40  MPa m〈sup〉1/2〈/sup〉) to 400 °C (71.45  MPa m〈sup〉1/2〈/sup〉) but declines at 600 °C (62.55  MPa m〈sup〉1/2〈/sup〉). It is observed from fracture surface through SEM that the predominant fracture mechanism has changed from quasi-cleavage fracture at room temperature to ductile fracture at higher temperatures. In addition, the tortuosity of crack propagation path has a limited impact on the fracture toughness. Path selections for crack propagation are obtained through SEM observation which can be summarized as: cut through lamellar 〈em〉α〈/em〉, parallel to lamellar 〈em〉α〈/em〉, bypass the equiaxed 〈em〉α〈/em〉〈sub〉〈em〉p〈/em〉〈/sub〉 and cut through the equiaxed 〈em〉α〈/em〉〈sub〉〈em〉p〈/em〉〈/sub〉. Moreover, it is found that the intrinsic contribution is the primary reason leading to the change of the fracture toughness of Ti60 alloy under different temperatures. Meanwhile, it is noteworthy that the area of the crack tip plastic zone increases from RT to 400 °C but decreases at 600 °C, which is seen as the main impact of temperature on fracture toughness. To be exact, the CT sample with a larger area of the plastic zone could provide a higher 〈em〉K〈/em〉〈sub〉〈em〉1C〈/em〉〈/sub〉 value. Furthermore, a prediction model of 〈em〉K〈/em〉〈sub〉〈em〉1C〈/em〉〈/sub〉 based on tensile properties is established, which has a good accuracy with experimental results. The model is useful in predicting the fracture toughness of Ti60 alloy at different test temperatures.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Shuying Dong, Longji Xia, Fangyuan Zhang, Fengzi Li, Yuyao Wang, Lingfang Cui, Jinglan Feng, Jianhui Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The ZnSn(OH)〈sub〉6〈/sub〉 nanocubes were prepared under different pH (3–12.4) by liquid precipitation, well characterized and further used for wastewater treatment. The results indicated that the ZnSn(OH)〈sub〉6〈/sub〉 nanocubes prepared at pH = 11.1 possessed of uniform size distribution and excellent photocatalytic activity, the degradation efficiency to MB reaches 76.3% after 5 h natural sunlight irradiation. Subsequently, the prepared ZnSn(OH)〈sub〉6〈/sub〉 nanocubes was further thermal treated (200 °C, 24 h) in four different solvents, containing deionized water, stock solution, mixed solution (V〈sub〉water〈/sub〉: V〈sub〉ethanol〈/sub〉: V〈sub〉glacial acetic acid〈/sub〉 = 3:1:1) and ethanol, named as H-1, H-2, H-3 and H-4, respectively. H-2 and H-3 showed superior photocatalytic performance and the removal efficiency of MB improved to be almost 100%, as well as red-shifted light absorption edge and the band gap energies reduced 0.9 and 0.93 eV, respectively. Moreover, free radical capture experiments showed that the h〈sup〉+〈/sup〉 and ·O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 are the main active species for the ZnSn(OH)〈sub〉6〈/sub〉 nanocubes and H-2, respectively, while all these three ·OH, ·O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 and 〈sup〉1〈/sup〉O〈sub〉2〈/sub〉 radicals for H-3. Those results suggested that both pH regulation and thermal treatment could efficiently improve the microscopic morphology, crystal structure and photocatalytic activity of the ZnSn(OH)〈sub〉6〈/sub〉, which might pave the way for the artful design of other high-performance catalysts.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819332013-fx1.jpg" width="312" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 198〈/p〉 〈p〉Author(s): Chukwuka Odibi, Meisam Babaie, Ali Zare, Md. Nurun Nabi, Timothy A. Bodisco, Richard J. Brown〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study uses the first and second laws of thermodynamics to investigate the effect of oxygenated fuels on the quality and quantity of energy in a turbo-charged, common-rail six-cylinder diesel engine. This work was performed using a range of fuel oxygen content based on diesel, waste cooking biodiesel, and a triacetin. The experimental engine performance and emission data was collected at 12 engine operating modes. Energy and exergy parameters were calculated, and results showed that the use of oxygenated fuels can improve the thermal efficiency leading to lower exhaust energy loss. Waste cooking biodiesel (B100) exhibited the lowest exhaust loss fraction and highest thermal efficiency (up to 6% higher than diesel). Considering the exergy analysis, lower exhaust temperatures obtained with oxygenated fuels resulted in lower exhaust exergy loss (down to 80%) and higher exergetic efficiency (up to 10%). Since the investigated fuels were oxygenated, this study used the oxygen ratio (OR) instead of the equivalence ratio to provide a better understanding of the concept. The OR has increased with decreasing engine load and increasing engine speed. Increasing the OR decreased the fuel exergy, exhaust exergy and destruction efficiency. With the use of B100, there was a very high exergy destruction (up to 55%), which was seen to decrease with the addition of triacetin (down to 29%).〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Tingting Xu, Feng Xu, Gift Gladson Moyo, Yaya Sun, Zhihua Chen, Bo Xiao, Xun Wang, Zhiquan Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Syngas is an indispensable chemical raw material, which also can provide heat and power. Chemical looping reforming (CLR) with biofuels is one prospective method to produce syngas. M〈sub〉x〈/sub〉O〈sub〉y〈/sub〉 of 20 wt% (CuO, NiO and Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) supported on dolomite were prepared by the wet impregnation method used as the oxygen carriers (OCs) for syngas production in the CLR process with toluene in the lab-scale fixed bed reactor. The effects of the reduced temperature in FR and mass of OCs on the fuel conversion, syngas production and OCs utilization were studied. The study found that CuO/dolomite (CD) tended to generate CO〈sub〉2〈/sub〉, while Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/dolomite (FD) and NiO/dolomite (ND) were appropriate to syngas production. Although CD achieved the highest oxygen effective conversion of 95.90% at 950 °C and the best selectivity for CO〈sub〉2〈/sub〉, it was not a suitable OC for syngas production in CLR process since the cold gas efficiency, syngas yield and syngas purity for CD remained lowest under different reaction conditions. FD manifested the best performance at 900 °C with 30.0 g, exhibiting the highest cold gas efficiency and syngas yield of 54.23% and 1.16 Nm〈sup〉3〈/sup〉/L, and the corresponding syngas purity was 73.86%. The selection of temperature and mass of FD played a key role in the quality control of syngas. Low syngas purity and rapid deactivation in cyclic tests were main barriers for FD to behave as an excellent OC in the CLR process. Furthermore, ND was the most ideal OC of the three for syngas production with the optimum condition being at 900 °C with 20.0 g, the corresponding cold gas efficiency, syngas yield and syngas purity were 39.30%, 0.93 Nm〈sup〉3〈/sup〉/L and 90.59% respectively. ND exhibited the highest syngas purity of the three, and the satisfied H〈sub〉2〈/sub〉/CO ratios (around 2.0) were achieved under different reaction conditions.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Tan Wu, Long Shao, Xinli Wei, Xinling Ma, Guojie Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The ORC (organic Rankine cycle) system has the advantages of simple structure, environmental friendliness, reliability and low capital cost. The expander is the key device of energy conversion in the ORC system, and its performance has a direct influence on that of the ORC. In this paper, a self-designed and manufactured radial inflow turbine is applied to low temperature waste heat power generation. The numerical model for the internal flow of the radial inflow turbine is established, and the numerical results show a better agreement with the experimental data. Firstly, the influence of blade stagger angles on nozzle performance is studied. The study finds that with the decrement of stagger angles under specific angle ranges, the velocity coefficient increases. However, the efficiency of the nozzle decreases sharply when the stagger angle exceeds 30°. Secondly, the influence of the blade profile on the efficiency of the rotor is investigated. The results indicate that with 〈em〉t〈/em〉 increasing, the efficiency of the rotor firstly increases, then decreases quickly. It increases by 1% compared with that of the original rotor, when the 〈em〉t =〈/em〉 1.95. At last, the performance of the turbine is researched numerically. This paper discovers that total-to-static efficiency of the turbine increases by 1.7% compared with that of the original turbine. This research provides orientation and basis for the improvement of aerodynamic design and performance of radial inflow turbine. As for practical application, the study can provide certain reference for the structure and blade profile design of nozzles and rotors to further improve the performance, and to offer some data for the operational control and tests.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 198〈/p〉 〈p〉Author(s): Johanna Beiron, Rubén M. Montañés, Fredrik Normann, Filip Johnsson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As the share of non-dispatchable energy sources in power systems increases, thermal power plants are expected to experience load variations to a greater extent. Waste-fired combined heat and power has multiple products and is today primarily operated for waste incineration and to generate heat. To consider load variations in the power demand at these plants may be a way to provide system services and obtain revenue, however, the transient interaction between power and district heating generation for the type of steam systems used should be studied. This work describes the transient characteristics and timescales of cogeneration steam cycles to discuss the operational interactions between power and district heating generation. A dynamic model of the steam cycle of a 48 MW waste-fired combined heat and power plant is developed using physical equations and the modeling language Modelica. The model is successfully validated quantitatively for both steady-state and transient operation with data from a reference plant and is shown capable of characterizing the internal dynamics of combined heat and power plant processes. Simulations are performed to analyze steam cycle responses to step changes, ramps and sinusoidal disturbances of boiler load changes and variability in district heating inlet temperature and flow. The results give insight on the process timescales for the specific case studied; for example, with the present design a 10% boiler load change requires up to 15 min for responses to settle, while the corresponding time for a 10% change in district heating flow or temperature show settling times within 5 min. Furthermore, increasing the boiler ramp rate from 2 to 4%/min could reduce the rise time of power generation by 42%, which could be of economic significance in day-ahead power markets.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Guang Li, Zheyu Liu, Fan Liu, Bin Yang, Shuqi Ma, Yujing Weng, Yulong Zhang, Yitian Fang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Exergy-based analysis is a powerful method to evaluate, understand, and improve energy conversion processes. Compared with conventional exergy analysis, advanced exergy analysis can identify the improvement potential of each component and the interactions among components of the whole system. In this paper, the ash agglomerating fluidized bed (AFB) gasification process is simulated in Aspen Plus (version 8.0). Based on the simulation results, advanced exergy analysis is carried out to study the performance of the AFB gasification process. The exergy efficiency of the AFB gasification process is 82.13% and the total exergy destruction is 4670 kW. The result shows that 54.18% of the total exergy destruction can be avoided. The AFB gasifier has the largest potential for reducing exergy destruction. In addition, sensitivity analysis is performed to research the effects of carbon conversion, pressure and temperature on the exergy destruction of the AFB gasifier.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Juliano Pierezan, Gabriel Maidl, Eduardo Massashi Yamao, Leandro dos Santos Coelho, Viviana Cocco Mariani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the past decades, the quantity of researches regarding industrial gas turbines (GT) has increased exponentially in terms of number of publications and diversity of applications. The GTs offer high power output along with a high combined cycle efficiency and high fuel flexibility. As consequence, the energy efficiency, the pressure oscillations, the pollutant emissions and the fault diagnosis have become some of the recent concerns related to this type of equipment. In order to solve these GTs related problems and many other real-world engineering and industry 4.0 issues, a set of new technological approaches have been tested, such as the combination of Artificial Neural Networks (ANN) and metaheuristics for global optimization. In this paper, the recently proposed metaheuristic denoted Coyote Optimization Algorithm (COA) is applied to the operation optimization of a heavy duty gas turbine placed in Brazil and used in power generation. The global goal is to find the best valves setup to reduce the fuel consumption while coping with environmental and physical constraints from its operation. In order to treat it as an optimization problem, an integrated simulation model is implemented from original data-driven models and others previously proposed in literature. Moreover, a new version of the COA that links some concepts from Cultural Algorithms (CA) is proposed, which is validated under a set of benchmarks functions from the Institute of Electrical and Electronics Engineers (IEEE) Congress on Evolutionary Computation (CEC) 2017 and tested to the GT problem. The results show that the proposed Cultural Coyote Optimization Algorithm (CCOA) outperforms its counterpart for benchmark functions. Further, non-parametric statistical significance tests prove that the CCOA’s performance is competitive when compared to other state-of-the-art metaheuristics after a set of experiments for five case studies. In addition, the convergence analysis shows that the cultural mechanism employed in the CCOA has improved the COA balance between exploration and exploitation. As a result, the CCOA can improve the current GT operation significantly, reducing the fuel consumption up to 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si94.svg"〉〈mrow〉〈mn〉3.6〈/mn〉〈mo〉%〈/mo〉〈/mrow〉〈/math〉 meanwhile all constraints are accomplished.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Wei Liu, Cheng Chen, Huijuan Wu, Chunhui Guo, Yuedong Chen, Wenqiu Liu, Zhaojie Cui〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, a cradle-to-grave life cycle assessment was conducted on several typical domestic hot water systems across five climatic regions of China. Variations of the climate and energy supply in these regions and the energy efficiency grade of domestic hot water systems were also taken into consideration. The results suggest that evacuated tube solar systems are highly energy-efficient and low-cost, except in the region with the weakest solar radiation. Electric systems are extremely energy-intensive and uneconomical for domestic hot water use, although they have the least human and ecological toxicity potentials. Solar and air-source energy systems save energy; however, they use more materials and cause more human and ecological toxicity. From the severe cold region to the hot summer and warm winter region, the heat load of domestic hot water increases by 59%, resulting in an increase of 58–230% in primary energy demand. Accordingly, the environmental impacts of domestic hot water systems increase in varying degrees; however, few impacts decrease due to the different emission factors of different power grids. The raw materials used in the manufacture of domestic hot water systems and the energy required for the use of the systems are the most important contributors to all environmental impacts. The scenario analysis indicates that 24.5% of the primary energy demand and 25.7% of greenhouse gas emissions owing to domestic hot water use in China can be reduced by improving the energy efficiency, prompting the use of renewable energy sources, and reducing the usage of materials for domestic hot water systems, as the human and ecological toxicity potentials will increase by 0.1% and 10%, respectively, due to the increasing use of certain materials.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S019689041930946X-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Dongdong Zhang, Qiang Yang, Kai Guan, Baishun Li, Nan Wang, Pengfei Qin, Bo Jiang, Chi Sun, Xin Qin, Zheng Tian, Zhanyi Cao, Jian Meng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A high-strength low-rare-earth-alloyed Mg−3.5Sm−2Yb−0.6Zn−0.4Zr alloy was processed by an ingot metallurgy process with hot-extrusion followed by artificial aging. The peak-aged sample exhibited a higher yield strength of 449 MPa than most of extruded Mg−Gd based alloy containing high RE content, and even is comparable to that of the T8-treated 2024 Al alloy. The studied alloy exhibited a typical bimodal microstructure, consisting of dynamically recrystallized (DRXed) grains with random textures and coarse unrecrystallized regions with strong basal fiber texture. In addition, the fragmented Mg〈sub〉5〈/sub〉RE and Mg〈sub〉41〈/sub〉RE〈sub〉5〈/sub〉 phases distributed at extrusion stringers. Abundant of fine Mg〈sub〉3〈/sub〉RE particles precipitated dynamically in DXRed regions, which restrains DRXed grains growth effectively by grain boundary pinning. Within the unDXRed regions, uniformly dense Mg〈sub〉3〈/sub〉RE and Mg〈sub〉12〈/sub〉RE nano-precipitates were observed. Also there were many basal 〈〈strong〉a〈/strong〉〉 dislocations and a few non-basal 〈〈strong〉c〈/strong〉 + 〈strong〉a〈/strong〉〉 dislocations in unDXRed regions. Subsequent artificial ageing significantly enhanced the alloy's strength by introducing basal precipitates, although decreased the ductility slightly. Finally, the ultrahigh yield strength was revealed to be attributed to the combined effects of a strong basal fiber texture, a bimodal microstructure, and numerous precipitated particles.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds〈/p〉 〈p〉Author(s): Sunil Chauhan, Manoj Kumar, Himanshu Pandey, Sandeep Chhoker, S.C. Katyal〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ca and Ca–Li substitution dependent modification in structural, electron density, vibrational, magnetic and optical properties of BiFeO〈sub〉3〈/sub〉 nanoparticles synthesized by tartaric acid based sol–gel route are reported. X-ray diffraction and transmission electron microscopy techniques revealed the phase purity and nanocrystalline nature of BiFeO〈sub〉3〈/sub〉, Bi〈sub〉0·95〈/sub〉Ca〈sub〉0·05〈/sub〉FeO〈sub〉3〈/sub〉, Bi〈sub〉0·95〈/sub〉Ca〈sub〉0·05〈/sub〉Fe〈sub〉0·95〈/sub〉Li〈sub〉0·05〈/sub〉O〈sub〉3〈/sub〉 samples. The electron density plots indicated the displacement of Bi and Fe ions and partial covalency of Bi–O and Fe–O the bonds. The Ca and Ca–Li ions substitution induced distortion in rhombohedral structure resulting in enhanced magnetization of BiFeO〈sub〉3〈/sub〉 nanoparticles. The magnetization is highest for Ca–Li substituted BiFeO〈sub〉3〈/sub〉 nanoparticles with saturation magnetization of 0.036 emu/g due to the canted spin structure and uncompensated surface spins. The enhanced magnetic properties are also endorsed by the electron spin resonance and Raman studies. The band-gap of BiFeO〈sub〉3〈/sub〉 nanoparticles can be tuned by aliovalent ions substitution from 2.26 eV for BiFeO〈sub〉3〈/sub〉 to 2.20 and 2.17 eV for Ca, and Ca–Li substituted BiFeO〈sub〉3〈/sub〉 nanoparticles respectively.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Lifeng Sun, Junjie Shi, Chengjun Liu, Maofa Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the purpose of providing fundamental understanding of equilibrium phase relations with the addition of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 to CaO–SiO〈sub〉2〈/sub〉-5wt%MgO–Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉–TiO〈sub〉2〈/sub〉 system, the equilibria phase relations were experimental determined from 1300 °C to 1450 °C at constant 〈em〉w〈/em〉(CaO)/〈em〉w〈/em〉(SiO〈sub〉2〈/sub〉) ratio of 1.50 using high temperature equilibrium and quenching method followed by XRD (X-Ray diffraction) and SEM-EDX (Scanning Electron Microscope and Energy Dispersive X-ray Fluorescence scope) analysis. The results showed that with the increase of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 content up to 30 wt%, the coexisting equilibria solid phases gradually changed from perovskite of CaO·TiO〈sub〉2〈/sub〉 and melilite solid solution of (2CaO·Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉·SiO〈sub〉2〈/sub〉, 2CaO·MgO·2SiO〈sub〉2〈/sub〉)〈sub〉ss〈/sub〉 to spinel of MgO·Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. Comparisons with the predictions by Factsage revealed that the simulated results were only well agreed when Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 content lower than 20 wt%, while significant discrepancies existed with Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 content higher than 30 wt%. Finally, the 1400 °C and 1450 °C isotherms, as well as the predicted primary phase boundary lines were projected on the pseudo-ternary phase diagram of CaO–SiO〈sub〉2〈/sub〉-5wt.%MgO–Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉–TiO〈sub〉2〈/sub〉 system within specific composition range.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Mustafa A. Ahmed, Liza Coetsee, Walter E. Meyer, Jackie M. Nel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Schottky diodes based on ZnO nanorods, undoped and co-doped with different concentrations (0.0, 0.2, 0.4, 0.6 and 0.8 at.%) of Ce and Sm, were fabricated on glass and on n-Si (111) substrates using chemical bath deposition assisted with the sol-gel spin coating. The ZnO maintained its hexagonal shape up to higher levels of doping (0.8 at.%) with the growth rate being suppressed by Ce and Sm co-doping. The as-synthesized nanorods were found to be highly crystalline and no impurities or peaks related to Ce and Sm or their oxides were observed. Room temperature Raman spectroscopy revealed that the prominent E〈sub〉2〈/sub〉 high peak shifted towards a lower wave number and the intensity decreased upon doping. X-ray photoelectron spectroscopy studies at room temperature showed that the presence of Zn and O in all samples with small amounts of Ce and Sm being detected at doping levels of 0.8 at.%. Photoluminescence studies at room temperature revealed a weak ultraviolet emission and a strong deep level (visible) emission. Deconvolution of the visible emission spectra showed that more than one defect contributed to the visible emission. The 〈em〉I–V〈/em〉 characteristics of the fabricated Schottky diode devices measured at room temperature showed that the Ce and Sm co-doping increased the generation-recombination process in the fabricated Schottky diodes. Furthermore, the current transport mechanism in the fabricated Schottky devices at a lower voltage (0.0–〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mo〉∼〈/mo〉〈/mrow〉〈/math〉 0.6 V) was dominated by ohmic conduction mechanism, while at voltages greater than 0.6 V, the space charge limited current and the trap filled limit voltage mechanism dominated.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Ling Guo, Liyun Cao, Jianfeng Huang, Yong Wang, Wenbin Li, Hui Qi, Shaoyi Chen, Jiayin Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Owing to the high theoretical capacity, Sb〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 has been regarded as one of the best choices for Sodium-ion batteries (SIBs) anode materials. However, Sb〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 anode suffers from huge volume change with poor electrode structure stability, resulting in limited cycling and rate performance. Herein, inspired by the formation of inclusion complex an effective strategy for improving unstable molecules in biological fields, we encapsulate Sb〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 in capsular carbon shell via a hydrothermal and calcinations process. Furthermore, by adjusting the thickness of the capsule carbon shell, an ultra-stable Sb〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 electrode structure is realized. Equipped with this ultra-stable electrode structure, Sb〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 anode exhibits high capacity of 475 mA h g〈sup〉−1〈/sup〉 at 2 A g〈sup〉−1〈/sup〉 even after 600 cycles, showing compelling advantage on Na storage performance compared to other reported Sb-based anode materials. The analysis results indicate that the intact capsular carbon shell can effectively remit huge volume change of Sb〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉, and act like a reaction vessel in which the sodiation/desodiation reaction of Sb〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 is carried out regularly. Therefore, this ultra-stable electrode provides stable redox reactions, easy charge transfer and fast sodium ion diffusion, resulting in excellent Na storage performance of Sb〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 anode.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Encapsulating Sb〈sub〉2〈/sub〉Se〈sub〉3〈/sub〉 in capsular carbon shell to from inclusion complex can achieve ultra-stable electrode structure with excellent Na storage performance.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819331706-fx1.jpg" width="466" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Zhonghe Han, Xiaoqiang Jia, Peng Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Organic Rankine cycle (ORC) is an efficient technique to recycle the low temperature heat sources. The design method of the critical component, radial inflow turbine, is a main focus of research. A preliminary design method was developed to optimize eight critical parameters based on particle swarm optimization (PSO) algorithm. The isotropic efficiency was the objective function of the algorithm. Six working fluids were selected to conduct turbine design based on the design method. The turbine with R245fa was determined to be optimal due to its small geometry size, high exergy efficiency (0.929) and high load coefficient (1.1027). The off-design performance of R245fa turbine was investigated with the variation of pressure ratio (〈em〉PR〈/em〉), stator inlet temperature and power output. The results indicate that the turbine efficiencies increase with the reduction of 〈em〉PR〈/em〉 and turbine inlet temperature and the increase of power output. The exergy efficiency and isotropic efficiency drop slightly with the increase of turbine inlet temperature. So the turbine with R245fa exhibited good off-design performance.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Yifan Li, Gaoqiang Yang, Shule Yu, Zhenye Kang, Derrick A. Talley, Feng-Yuan Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The heat generated from electrochemical reactions has been considered one of the most significant issues in terms of the reliability of energy conversion devices. So far, no systematic study on the relation between heat generation and electrochemical reaction exists, especially in the form of experiments. In this study, changes of the temperature distribution and hydrogen evolution reaction (HER) on the catalyst coated membrane (CCM) in proton exchange membrane electrolyzer cells (PEMECs) are 〈em〉in-situ〈/em〉 visualized with the help of a novel PEMEC design, thermal spectroscopy and high-speed visualization system. At the channel-scale, the temperature increases rapidly for most of the active areas, and finally reaches the equilibrium state at 27 °C. The temperature distribution is non-uniform throughout the process. In addition, a series of pore-scale analyses are provided to clarify the relation between the temperature distribution and electrochemical reaction area. More interestingly, the rapid heat generation areas are found to be in a good agreement with the electrochemical reaction areas, which confirms that the heat is released during the reaction processes. Finally, the temperature evolution phenomena on the LGDL surface have also been recorded. These findings could help better understand the correlation between the cathode side electrochemical reaction and heat generation.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Jiangjiang Wang, Yuzhu Chen, Noam Lior〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study integrates concentrated photovoltaic/thermal (PV/T) solar collectors into a natural gas combined cooling, heating and power (CCHP) system to both offer efficient use of solar energy and reduce greenhouse emissions. Using exergo-economic analysis based on energy level, an optimization method was proposed and used to configure and determine the PV coverage ratio on the PV/T collector for minimizing the products’ costs of the hybrid CCHP system. The optimization method considers the users’ annual variable energy loads and transforms the off-design operation conditions to the design parameters by employing the heat storage ratio of thermal storage tank and supplemental heat ratio of absorption heat pump. Based on the validated thermodynamic modeling, an exergy and exergo-economic analysis of the hybrid CCHP system are presented to reveal the influences of the PV/T configuration on the exergy efficiency and the products’ cost. As the PV coverage ratio on the PV/T collector was increased, it was found that the specific cost of the CCHP system-generated electricity rose and then slightly dropped, while the specific cost of the heat exergy decreased, and then slightly increased. The optimal coverage ratio, at which the minimal specific cost of the system products was attained, had a value of 1.0. The integration and optimization of the PV/T decreases the specific cost of the system products by 6.4%. Compared to the conventional exergo-economics analysis method, the specific cost of system electricity using the exergo-economic analysis based on energy level is 20.3% higher, and the costs of heat exergy are decreased.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Nicu Bizon〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, a real-time strategy for a fuel cell hybrid power system based on fuel optimization and load-following is analyzed to identify the critical parameters of the optimization problem. Because the dither’s frequency dictates the searching speed of the optimum in the perturbed extremum seeking algorithm, this parameter has been selected from multiple parameters involved in the optimization problem to improve the fuel economy based on sensitivity analysis. The sensitivity analysis reveals the multimodal behavior of the fuel economy, but also the best choice for the dither. The fuel cell hybrid power system is a highly dynamic system, so the optimization and control loops have been designed for a robust but efficient operation of the system based on new perturbed extremum seeking algorithm to track the optimum. Considering the recommended 100 Hz sinusoidal dither, the improvement in fuel economy is of 47.9 L for an 8 kW/12 s load cycle. Also, the electrical efficiency of the fuel cell system increases with 7.83%. Both improvements were estimated compared to a commercial strategy, called in the literature as static feed-forward strategy.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 198〈/p〉 〈p〉Author(s): Minda Ma, Xin Ma, Weiguang Cai, Wei Cai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon-dioxide mitigation in residential building sector (CMRBS) has become critical for China in achieving its emission mitigation goal in the “Post Paris” period with the growing demand for household energy service in residential buildings. This is the first paper to investigate the factors that can mitigate carbon-dioxide (CO〈sub〉2〈/sub〉) intensity and further assess CMRBS in China based on a household scale via decomposition analysis. The core findings of this study reveal that: (1) Three types of housing economic indicators and the final emission factor significantly contributed to the decrease in CO〈sub〉2〈/sub〉 intensity in the residential building sector. In addition, the CMRBS from 2001 to 2016 was 1816.99 MtCO〈sub〉2〈/sub〉, and the average mitigation intensity during this period was 266.12 kgCO〈sub〉2〈/sub〉·(household·year)〈sup〉−1〈/sup〉. (2) Ridge regression indicated that the robustness of the decomposition approach was sufficient for achieving reliable results for the decomposition analysis and CMRBS assessment. (3) The energy-conservation and emission-mitigation strategy caused CMRBS to effectively increase and is the key to promoting a more significant emission mitigation in the future. Overall, this paper covers the CMRBS assessment gap in China, and the proposed assessment model can be regarded as a reference for other countries and cities for measuring the retrospective CO〈sub〉2〈/sub〉 mitigation effect in residential buildings.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉 〈p〉a. Changes of CO〈sub〉2〈/sub〉 emission per household (CO〈sub〉2〈/sub〉 intensity) in the Chinese residential building sector via decomposition analysis; b and c. Total and intensity values of CO〈sub〉2〈/sub〉 mitigation in the residential building sector (2001–2016); d and e. CO〈sub〉2〈/sub〉 mitigation per capita and CO〈sub〉2〈/sub〉 mitigation per floor space in the residential building sector (2001–2016).〈/p〉 〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419309069-ga1.jpg" width="406" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): Hang Li, Zunlong Jin, Yi Yang, Yaowu Huo, Xiao Yan, Pan Zhao, Yiping Dai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nuclear energy with attractive expectation can be efficiently used by the supercritical carbon dioxide power system. However, amounts of the cooling heat is wasted in the nuclear power plant. Two conceptual designs of combined heat and power systems based on the supercritical carbon dioxide power system are proposed to exploit the waste heat. A comparison research is performed in thermodynamics and economics. Several key physical parameters are selected to investigate their effects on system performance, and multi-objective optimization using the Non-dominated Sorting Genetic Algorithms-II is carried out with the target of gaining maximum system exergy efficiency and minimum total product unit cost. The results of parameter analysis exhibit that there exist optimal values for two target functions with the increasing compressor pressure ratio for three thermal systems, and the system with heat pump needs the highest pressure ratio. Better system performance can be achieved by increasing the turbine inlet temperature and evaporator temperature. The multi-objective optimization results of genetic algorithm display that proposed two systems can gain an improvement by 7.02% and 8.45% for the system exergy efficiency, and 11.95% and 13.48% for the total product unit cost compared with the stand-alone supercritical carbon dioxide system, respectively.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): David Sedmidubský, Vít Jakeš, Kateřina Rubešová, Pavla Nekvindová, Tomáš Hlásek, Roman Yatskiv, Pavel Novák〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Using the recently developed method based on a combination of DFT plane wave code applied to extract the crystal field parameters and a local atomic like Hamiltonian involving electron-electron, spin-orbit and Zeeman terms we calculated the energy levels of ground and excited multiplets of Yb〈sup〉3+〈/sup〉 and Er〈sup〉3+〈/sup〉 ions hosted in ytterbium and yttrium aluminum garnet (YbAG and YAG) including their crystal and magnetic field splitting. The obtained energy levels and derived magnetic properties are compared with the experimental data from magnetometry, photoluminiscence and near-infrared spectroscopy.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819331421-fx1.jpg" width="242" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 30 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 811〈/p〉 〈p〉Author(s): Yan Jia, Si'an Chen, Yong Li, Song Wang, Haifeng Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉C/C–ZrC–SiC–ZrB〈sub〉2〈/sub〉 composites were prepared by a joint process of precursor infiltration and pyrolysis and slurry infiltration. The high-temperature mechanical properties of the composites were reported and the evolution of fracture behavior and microstructure was analyzed. The composites exhibited a tensile strength and flexural strength of 99.3 MPa and 281 MPa, respectively during the test at ambient temperature. The high temperature in-situ tensile properties were higher than those at ambient temperature; the tensile strength was 136 MPa during the tensile test at 1700 °C. This is because the energy absorption mechanisms will occurred during the high-temperature test. The high temperature in-situ flexural strength was 223 MPa during flexural test at 1800 °C. However, the flexural strength of as-prepared composites after heat treat at 1800 °C was maintained at 153 MPa, which was lower than that of the in-situ flexural test at 1800 °C, because the fibers were more seriously eroded after heat treatment at 1800 °C. After heat treatment at 2400 °C, the flexural strength of the composites decreased to 88 MPa. It can be inferred that the high temperature in-situ flexural strength at 2400 °C was higher than 88 MPa, showing outstanding ultra-high temperature mechanical properties. Therefore, the C/C–ZrC–SiC–ZrB〈sub〉2〈/sub〉 composites are promising to be applied as structural material in aerospace, due to their excellent high-temperature mechanial properties at 1500 °C–2400 °C.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Qi Li, Liguo Yue, Li Li, Hui Liu, Wenqin Yao, Ning Wu, Longwen Zhang, Hao Guo, Wu Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nitrogen sulfur co-doped bimetal nanocomposites (NS-BNs) are prepared through vulcanization and annealing using bimetallic Ni/Co-MOF as a precursor. The nitrogen sulfur co-doped bimetal nanocomposites have abundant electroactive sites and redox reaction centres, which exhibit remarkable electrochemical performance as electrode materials for supercapacitor. The specific capacitance could reach 1529 F g〈sup〉−1〈/sup〉 at a current density of 1 A g〈sup〉−1〈/sup〉 and excellent cycle stability (retention rate of 89.29% after 10000 cycles). After the current density is expanded ten times, the specific capacitance can still reach 1069 F g〈sup〉−1〈/sup〉, indicating superior rate performance. Furthermore, the assembled asymmetric supercapacitor displayed a high energy density of 41.04 Wh kg〈sup〉−1〈/sup〉 at power density of 750 W kg〈sup〉−1〈/sup〉. As a result, non-metal doped nanocomposites material has promised applications for electrochemical supercapacitors.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819332074-fx1.jpg" width="346" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): Yun Wei, Yupeng Shi, Zhiyang Jiang, Xuefeng Zhang, Huihui Chen, Yahong Zhang, Jingwei Zhang, Chunhong Gong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, titanium nitride (TiN)/reduced graphene oxide (RGO) composites were prepared via a facile hydrothermal and thermal nitridation process. Due to their favorable electromagnetic wave dissipation ability and appropriate electromagnetic (EM) impedance matching, the TiN/RGO flakes embodies distinct advantage as compared to single component RGO nanosheets and TiN nanoparticles. Moreover, the effective electromagnetic absorption frequency range of the TiN/RGO flakes could be designed by controlling the mass ratio of the precursor. When the mass ratio of nanosized titanic acid to graphene oxide is 1.4:1, the reflection loss of the TiN/RGO with only 2.0 wt% absorber loading reaches −42.85 dB at 8.88 GHz with a thickness of 4.0 mm and a broad effective absorption bandwidth (〈em〉R〈/em〉L 〈 −10 dB) of 6.7 GHz, which compete well with those observed in several RGO-based composites with much higher filler loadings. The combined excellent EM absorption property with simple production procedure and ultralow absorbent content requirement endow the TiN/RGO flakes as a promising lightweight and efficient EM absorption material suitable for harsh application conditions.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 810〈/p〉 〈p〉Author(s): X.H. Shi, C. Zhao, Z.H. Cao, Z.H. Wang, R.P. Guo, J.W. Qiao, Y.C. Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The yielding, deformation and fracture behavior for the Widmanstätten structure of Ti–8Al–1Mo–1V alloy upon high speed impact were studied through characterization and discussion. Seven strain rates ranging from 870 s〈sup〉−1〈/sup〉 to 3300 s〈sup〉−1〈/sup〉 were applied. The results show that: The yield strength of Widmanstätten structure shows two distinct changing stages among the whole range of strain rates. Under the strain rates below 2250 s〈sup〉−1〈/sup〉, Widmanstätten structure exhibits positive strain rate sensitivity. Surprisingly, under the strain rates from 2250 s〈sup〉−1〈/sup〉 to 3300 s〈sup〉−1〈/sup〉, it shows negative strain rate sensitivity. The increasing importance of twinning in the initiation of plastic deformation with higher strain rate is deemed as the reason causing this phenomenon. The dynamic compression behavior of Widmanstätten structure is described by J-C model, which shows unstable prediction performance. Adiabatic shearing band starts forming under the strain rates above 1950 s〈sup〉−1〈/sup〉, from which the fracture behavior of Widmanstätten structure is analyzed. An interesting phenomenon is that the adiabatic shearing band thicknesses at different locations of specimen can be obviously different. This is attributed to the relative orientation of α lamellae to the biggest shear stress plane. Saw-tooth chips start forming at the two end faces of specimen under the strain rates above 2500 s〈sup〉−1〈/sup〉, and its formation mechanism is thoroughly discussed. Adiabatic shearing band after post annealing was characterized by EBSD, which shows recrystallized grains with gradient diameters. In addition, it is found that the Burgers orientation relationship of the microstructure outside adiabatic shearing band was generally retained during the dynamic loading and post-annealing process.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 198〈/p〉 〈p〉Author(s): K. Chopra, V.V. Tyagi, Atin K. Pathak, A.K. Pandey, Ahmet Sari〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉In this study, the thermal performance of a novel solar collector integrated with stearic acid as phase change material has been investigated. In this design, the solar radiation was collected by heat pipe equipped evacuated tubes and then stored in manifold integrated with phase change material. The stored thermal energy of phase change material then transferred to water flowing through bundle of finned copper pipes placed inside the manifold. In present study, the design, the operating principle and the experimental investigation of the developed system have been presented. The developed system was investigated with different mass flow rates and also discussed the influence of varying mass flow rate on the thermal performance of system. The experimental investigation of designed and developed system has been carried out for two modes i.e. mid-day charging mode and full-day charging mode. It has been observed that for considered mass flow rates, thermal efficiency of the system was varied in the range of approximately 52–62% for full-day charging mode while for mid-day charging mode, it was varied between 55 and 72%. The maximum value of thermal efficiency was approximately 72.52% at mass flow rate of 24 LPH for mid-day charging mode. The efficiency of phase change material for both modes was varied in the range of approximately 61–64%. The annual cost and annual fuel cost of the developed system are much lower than conventional system. Also, the initial capital cost for the developed system can be recovered after 6 years of operation. However, there is no recovery of initial investment for electricity based water heating system.〈/p〉 〈p〉The proposed system overcomes two problems associated with conventional heat pipe evacuated tube solar collector: elimination of heat pipe overheating problem and low thermal conductivity of phase change materials. By this novel design of manifold, the influence of thermal stratification on the thermal performance of solar collectors can be completely eradicated.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 199〈/p〉 〈p〉Author(s): M.E. Demir, G. Chehade, I. Dincer, B. Yuzer, H. Selcuk〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The synergistic effects of titanium dioxide photocatalysis in combination with Fenton-like reactions for photoelectrochemical based hydrogen production and wastewater treatment is investigated in a newly designed photoelectrochemical reactor. Here, titanium dioxide nanoparticles are coated on the anode to enhance both hydrogen production and wastewater treatment processes. The reactor is tested under 600 W/m〈sup〉2〈/sup〉 of solar irradiance and is characterized using electrochemical, chemical oxygen demand, absorbance, and ultraviolet–visible absorption spectroscopy techniques. The results show that the oxygen evaluation in the anolyte is substituted by iron(II)/iron(III) ions and the presence of hydrogen peroxide forms up the hydroxyl radicals via Fenton like process for degradation of organics in wastewater. While, hydrogen gas production in the catholyte is improved up to 8% by the means of proton reduction at the cathode in an acid medium. Also, 33% chemical oxygen demand removal efficiency of the synthetic textile wastewater (Reactive Black 5) is recorded in 17 h. This new hybrid configuration combines three different photo-assisted advanced oxidation processes such as ultraviolet/Fenton, ultraviolet/titanium dioxide, and ultraviolet/hydrogen peroxide with electrolysis process which increases hydrogen gas production rate and treats the wastewater.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419308945-ga1.jpg" width="347" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 197〈/p〉 〈p〉Author(s): Dechao Wang, Lijun Jin, Yang Li, Baoyong Wei, Demeng Yao, Haoquan Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To understand the effect of reducibility of transition metal oxides (TMOs) on tar conversion, four TMOs including Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, MnO〈sub〉x〈/sub〉, CuO, and NiO were selected and in-situ oxidative catalytic cracking of coal pyrolysis tar on a two-stage fixed bed reactor at 550 °C was performed. The reducibility of TMOs was measured by H〈sub〉2〈/sub〉-temperature programmed reduction (H〈sub〉2〈/sub〉-TPR). The effect of reducibility of TMOs on the pyrolysis products distribution and conversion was investigated. The changes of TMOs before and after reaction were also analyzed by several characterizations. The addition of TMOs results in the decrease of tar yield and heavy tar content, and the increase of gas yield. The reduction temperature of TMOs affects the products distribution and heavy tar conversion. Among these four TMOs, Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 shows the highest reduction temperature (390–700 °C with peak centered on 570 °C) and the largest heavy tar conversion (75.3 wt%). CuO shows the lowest reduction temperature (190–470 °C with peak centered on 326 °C) and heavy tar conversion (45.8 wt%). The main reactions on CuO is complete oxidation with high water yield (12.8 wt%) and CO〈sub〉2〈/sub〉 formation (110 mL/g.coal〈sub〉daf〈/sub〉). The coke formed on the used Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 is amorphous or disordered carbon, and shows the largest yield being 5.5 wt%.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419308532-ga1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 197〈/p〉 〈p〉Author(s): Diego Vittorini, Roberto Cipollone, Roberto Carapellucci〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The full exploitation of the upper thermal source is the key for enhanced energy performances of ORC-based units for medium and low-grade waste heat recovery. The adoption of a dual evaporation pressure cycle layout has the potential to reduce the heat exchange irreversibility at the evaporation section and to assure a higher net power available at the expander shaft, particularly in small scale units and in presence of upper thermal sources with a highly variable heat release characteristic. The adoption of the dual evaporation pressure technology to small scale recovery units represents a major technological breakthrough and an element of novelty, observing that, at present, the possibility to split the evaporation process in multiple pressure levels is considered mostly with reference to steam generators and boilers. The study investigates the potential energy and exergy advantage of a dual pressure heat recovery vapor generator, with respect to a base-single evaporation pressure layout, for a recovery unit with a mechanical power in the 1–15 kW range, for stationary (100 °C–150 °C hot source temperature) and on-board (350 °C–300 °C hot source temperature) applications. A dedicated optimization procedure allows the maximization of either the net power recovered or the cycle energy efficiency, dependently on the final application of the unit. The exergy efficiency of the heat recovery vapor generator is assessed and its dependence on the fluid characteristics and the main cycle variables discussed, along with the relationship between the energy and exergy gain for the enhanced heat exchange. A preliminary economic analysis provides a first indication of the financial merit of the dual evaporation pressure layout with respect to a base single evaporation pressure configuration.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 197〈/p〉 〈p〉Author(s): Seyed Sina Hosseini, Mehdi Mehrpooya, Ali Sulaiman Alsagri, Abdulrahman A. Alrobaian〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The object of this paper is to develop and exergetically assess a multi-generation system comprised of a Molten Carbonate Fuel Cell (MCFC) coupled with Steam Methane Reforming (SMR), Methanol Synthesis Process (MSP) with distillation process, and combined heat and power cycle (CHP) including gas turbine, Rankine cycle (RC), Organic Rankine Cycle (ORC) and District Heating (DH) line. The combination of the MCFC, CHP and MSP can be considered as an innovative breakthrough in the field of energy systems, in light of the fact that the reforming compartment can mutually feed both MCFC and MSP, and the whole process can simultaneously produce electricity, pure methanol and hot water. The SMR at 800 kPa and 600 °C was applied to produce synthetic gas required by MCFC and MSP. The simulation was performed by Aspen Hysys, considering several operational conditions and the best was selected according to exergetic performance assessment. The structure produced 110,544 kW net electricity (34% MCFC, 33.4% gas turbine, 18.4% RC and 14.2% ORC), pure methanol (99.9%) at 271.7 kgmole/h, and hot water at 80 °C and 65398.7 kgmole/h. About 23% and 21% of the overall destructed exergy belonged to combustion chamber and MCFC, respectively. The overall exergy destruction, exergy efficiency and energy efficiency of the integrated system were obtained 116,353 kW, 58.4% and 83.7%, respectively. Finally, the performance of the proposed hybrid system was compared with similar studies and it was found that the hybrid MCFC-MSP-CHP system can outstandingly enhance the overall efficiency and reduce CO〈sub〉2〈/sub〉 emissions.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S019689041930860X-ga1.jpg" width="357" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 25 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 806〈/p〉 〈p〉Author(s): Krishna K. Pawar, Jasmin S. Shaikh, Sawanta S. Mali, Yuvraj H. Navale, Vikas B. Patil, Chang K. Hong, Pramod S. Patil〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Herein, we report a facile approach for the synthesis of hollow Indium oxide (In〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) microcubes (HIMC) by two step process which consist of hydrothermal method and followed by air annealing. Kirkendall effect has been employed to transform Indium hydroxide In(OH)〈sub〉3〈/sub〉 microcubes (IHMC) to HIMCs. Particularly, the formation of HIMC was studied as function of annealing time. The evolution of hollowness was discussed through Kirkendall effect. Fabricated HIMC films were used to detect NO〈sub〉2〈/sub〉 gas up to 100 ppm of concentration. We found that synthesized HIMC had a huge sensing response (S = 1401) towards 100 ppm NO〈sub〉2〈/sub〉 gas, which demonstrates the effect of HIMC over simple microcubes. Response (R〈sub〉s〈/sub〉 = 16s) and recovery (R〈sub〉c〈/sub〉 = 165s) time of sensor were very short, which enables sensor to work rapidly. Also, HIMC sensor found selective for NO〈sub〉2〈/sub〉 gas rather ammonia, acetone and carbon dioxide gases. NO〈sub〉2〈/sub〉 sensing mechanism for the case of HIMC based sensor was described as per well known oxide based chemiresistive theory. From observations, it is found that the fabricated (HIMC)〈sub〉3hr〈/sub〉 based sensor is highly selective and sensitive towards NO〈sub〉2〈/sub〉 gas at ppm level of concentration and could be undertaken for gas sensing application at various fields.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881932763X-fx1.jpg" width="240" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 200〈/p〉 〈p〉Author(s): Ranjana Chowdhury, Shiladitya Ghosh, Dinabandhu Manna, Sumona Das, Sambit Dutta, Sabine Kleinsteuber, Heike Sträuber, Md. Kamrul Hassan, Suvi Kuittinen, Ari Pappinen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lignocellulosic biomass (LCB), the most abundant renewable feedstock for bioenergy generation, is commonly converted to second generation bioalcohols, the main drop-in fuels for petroleum gasoline, through three technologies based on sugar, carboxylic acid and syngas platforms. The hybridization of either any two or three platforms altogether is a novel concept aimed at improvement of yield and quality (high heating value) of bioalcohols. This article reviews the present status of the integration techniques of hybrid platforms with an overall assessment of their advancement with respect to their individual counterpart as well as the challenges involved. It has been indicated that to extract the maximum benefit of hybridization, research studies should be spurred in the fields of kinetic analysis of all thermochemical and biochemical processes, microbial interaction, optimization of process parameters (pH, temperature), performance analysis of engine for the utilization of mixed product bioalcohols, sustainability analysis through the development of mathematical models for lab-scale operations and process simulation models for large scale units along with life cycle assessment. Moreover, pyrolysis of LCB has been identified as a unique central process for the supply of all intermediate compounds, namely, sugar, carboxylic acid and syngas during the hybrid networking of three platform technologies. In this context, the scheme of CONVER-B, a joint research project under the INNO-INDIGO partnership program, aiming at sustainable integration of the platforms to produce bio-alcohols from LCBs leaving zero effluent simultaneously with carbon sequestration potential has been introduced and discussed.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419311173-ga1.jpg" width="279" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 200〈/p〉 〈p〉Author(s): Tiancheng Ouyang, Zixiang Su, Guicong Huang, Zhongkai Zhao, Zhiping Wang, Nan Chen, Haozhong Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The severe energy crisis and environmental deterioration we face today requires the development of novel methods to control emissions and enhance energy savings. In this investigation, based on the thermodynamic theory, a combined system including a dual-loop organic Rankine cycle, absorption refrigeration, and flue gas purification is modeled. The system can use various forms of waste heat to realize cascade utilization. Initially, through comparisons with existing experimental data, we verified the accuracy of the numerical simulation. The parameters affecting system performance are analyzed and discussed comprehensively. In addition, considering the contribution of the refrigeration system, a genetic algorithm is used to calculate the equivalent system output power. The optimized equivalent output power, thermal efficiency, and exergy efficiency are calculated as 1668.47 kW, 59.6%, and 57.29%, respectively. The results of the emission reduction analysis indicate that the purification system exhibits excellent removal performance with a desulfurization and denitrification efficiency of 99.8% and 45.52%, respectively, and the energy regulatory metrics meet the 2020 emission requirements. Therefore, this novel design can be considered as a feasible method to resolve energy inefficiency and emission reduction in ships.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0196890419311082-ga1.jpg" width="212" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 200〈/p〉 〈p〉Author(s): Minghui Ge, Xiaowei Wang, Yulong Zhao, Shixue Wang, Liansheng Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The gasification process of liquified natural gas (LNG) releases a significant amount of cold energy. Traditional vaporizers release cold energy directly into the environment, resulting in energy wastage. In this study, a novel type of vaporizer with a thermoelectric generator (VTEG) that combines an air-heated vaporizer and thermoelectric power generation technology is designed. The heat transfer and generation characteristics of the VTEG are analyzed based on the modeling and calculations. The results reveal that compared with the traditional vaporizer, the outer wall temperature of the VTEG increases by 18.4–35.6 K, which mitigates the frosting problem on the surface of the vaporizer. When the fluid is in the liquid-phase and two-phase region, the generation efficiency is maintained between 1.57% and 2.12%. In the gas-phase region, a gradual decrease in the generation efficiency is observed in accordance with an increase in the natural gas temperature. Moreover, the low generation efficiency of the VTEG can be attributed to the low natural convection heat transfer coefficient outside the tube. An increase in tube length first results in an increase in the output power of the VTEG, which then decreases. An optimal tube length exists at which the VTEG output power is maximum value. In addition, the influence of the flow on the single-phase regions is more significant, wherein an approximately linear increase in the optimal tube length and maximum output power occur in accordance with an increase in the flow. Therefore, suitable selection of tube length of the VTEG is very important.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 809〈/p〉 〈p〉Author(s): Shubham Pandey, Robert J. Koch, Guangfang Li, Scott T. Misture, Hui Wang, Simon R. Phillpot〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉First principles calculations are used to elucidate the thermodynamic stability of Cu–Au alloys. Here, we particularly focus on the Au-rich compositions which lie extremely close to the convex-hull. We find that there are multiple metastable states that are superstructures of the layered L〈sub〉10〈/sub〉 Cu〈sub〉0.5〈/sub〉Au〈sub〉0.5〈/sub〉 ground state. We also examine the effect of epitaxy on the ordered ground states of Cu–Au phases when the underlying substrate is Au. We find that the Au-rich phases remain stable, depending on the growth planes, while the Cu-rich phases are destabilized. We relate these results to the dealloying and nucleation of Au-rich phases observed experimentally. We perform Nudged Elastic Band calculations in both ordered and disordered Cu–Au phases to determine the activation energies of diffusion. The ordered phases show unique minimum energy paths due to uniform local environments of the species, while the disordered phases show a distribution of transition states, governed by the local density and the local bonding environments of diffusing species.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Energy Conversion and Management, Volume 198〈/p〉 〈p〉Author(s): Jun Hou, Ziyou Song, Heath Hofmann, Jing Sun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hybrid energy storage systems have been widely used in transportation, microgrid and renewable energy applications to improve system efficiency and enhance reliability. However, parameter uncertainty can significantly affect system performance. In order to address this issue, an adaptive model predictive control is developed in this paper. Online parameter identification is used to mitigate parameter uncertainty, and model predictive control is used to optimally split power, deal with constraints, and achieve desired dynamic responses. A sensitivity analysis is conducted to identify major impact factors. In order to validate the proposed method, both simulation and experiments are performed to show the effectiveness of the proposed adaptive model predictive control. Compared to the model predictive control without online parameter identification, the power loss reduction can be as high as 15% in the experiments. This study focuses on all-electric ship energy management to mitigate load fluctuations and improve system efficiency and reliability. The proposed method could also be used in other applications.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 809〈/p〉 〈p〉Author(s): Pan Tan, Yi Yang, Yudong Sui, Qudong Wang, Yehua Jiang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influences of Al–10Sr or/and Al–5Ti–1B on the as-cast microstructure and the mechanical properties of Al–12Si–4Cu–2Ni–0.8 Mg alloys at elevated temperature were studied. Studies have shown that the addition of 0.1 wt% Ti has little effect on 0.02 wt% Sr modification, and the grain size decreases significantly. The addition of 0.1 wt% Ti could increases the mechanical properties at the room temperature and elevated temperature due to the grain refinement. However, owing to the modification of eutectic Si, the mechanical properties of the alloys increase at ambient temperature and then slightly decrease at elevated temperature. The Ultimate tensile strength and Yield strength of the alloy with 0.01 wt% Ti and 0.02 wt% Sr at ambient temperature were the maximum values of 249.5 Mpa and 207.5 Mpa, respectively. The specimen tensile fracture morphology under different temperature in most test temperature (25 °C, 200 °C) were characterized by brittle transgranular fracture, and when the test temperature reaches 350 °C, it is characterized by ductile fracture.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 809〈/p〉 〈p〉Author(s): Hang Li, Guoqiang Liu, Lizhu Sun, Shiyi Qiao, Peng Zhao, Hui Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two new compounds Na〈sub〉0.6〈/sub〉Li〈sub〉0.4〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉 and Na〈sub〉0.6〈/sub〉Zn〈sub〉0.2〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉 are synthesized by a simple solid-phase reaction route, and their electrochemical properties are investigated. Their charge-discharge mechanisms are investigated. In the voltage range of 1.5–4.4 V, the initial discharge capacities of Na〈sub〉0.6〈/sub〉Li〈sub〉0.4〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉 and Na〈sub〉0.6〈/sub〉Zn〈sub〉0.2〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉 are 128 mAh g〈sup〉−1〈/sup〉 and 193 mAh g〈sup〉−1〈/sup〉 at a current density of 17 mA g〈sup〉−1〈/sup〉, respectively. The cycle performance of Na〈sub〉0.6〈/sub〉Li〈sub〉0.4〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉 is better than that of Na〈sub〉0.6〈/sub〉Zn〈sub〉0.2〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉. In the voltage range of 2–4.4 V, the cycle performances of the two compounds Na〈sub〉0.6〈/sub〉Li〈sub〉0.4〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉 and Na〈sub〉0.6〈/sub〉Zn〈sub〉0.2〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉 are improved. The Na〈sup〉+〈/sup〉 ion diffusion coefficient of Na〈sub〉0.6〈/sub〉Zn〈sub〉0.2〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉 obtained by alternating current impedance is 9 times that of Na〈sub〉0.6〈/sub〉Li〈sub〉0.4〈/sub〉Mn〈sub〉0.75〈/sub〉O〈sub〉2〈/sub〉. The roles of doping Li and doping Zn on the electrochemical properties can be obtained from this study. The charge discharge mechanisms of the two compounds are further studied.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 809〈/p〉 〈p〉Author(s): Wei Wang, Mingwei Zhang, Le Xin, Shiting Shen, Jiwei Zhai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ba〈sub〉0.4〈/sub〉Sr〈sub〉0.6〈/sub〉TiO〈sub〉3〈/sub〉–ZnAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 composite ceramics have been synthesized by a solid-state sintering process. The relationship among phase composition, microstructures and dielectric properties has been investigated. For this composite system, high tunability of 31.50% (at 30 kV/cm), high Q value of 707 (at 3.683 GHz) and appropriate permittivity of 178 were achieved simultaneous at x = 70 wt%. With increasing ZnAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 content, the quality value is gradually enhanced, reflecting the composite effect at high ZnAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 content. Meanwhile, Curie temperature shifts towards higher temperature, because of the low ion diffusion between ferroelectric and dielectric phase along with grain size effect in the selected system. Dielectric diffuseness characteristic was studied by scaling empirical formula, which confirms the low ion diffusion between the BST and ZnAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 phases.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 809〈/p〉 〈p〉Author(s): W. Kan, B. Chen, H. Peng, Y. Liang, J. Lin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The grain morphology and texture control in electron beam melted (EBM) Ti-47Al-8Nb γ-TiAl alloy is considered. The EBM process window to obtain a columnar lamellar colony (CLC) grain structure was defined following a critical assessment of thermal gradient and liquid-solid interface velocity by using numerical simulation. Experimentally, an epitaxial grain growth during solidification of Ti-47Al-8Nb has been realised by using the optimum EBM parameter sets. The length of the CLC grain structure reached up to ∼600 μm (compared to the powder layer thickness of 70 μm). The texture analysis and phase identification performed using electron backscatter diffraction (EBSD) provided important insights in understanding the solidification and phase transformation processes during the EBM fabrication. It was found that the solidification path for EBM high Nb-TiAl alloy involves the high-temperature α-phase field (i.e. L+β→α and α→α〈sub〉2〈/sub〉+γ phase transformation processes). The epitaxial growth of prior β grains and the anchoring effect of residual B2-phase are very likely to be responsible for the formation of CLC microstructure.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838819329068-fx1.jpg" width="253" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉