ALBERT

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Sai Huang, Zhihao Wang, Qi Zhu, Xiaofei Shi, Xuejiao Wang, Xiaodong Li, Xudong Sun, Ji-Guang Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉RE(OH)〈sub〉2.94〈/sub〉(NO〈sub〉3〈/sub〉)〈sub〉0.06〈/sub〉·〈em〉n〈/em〉H〈sub〉2〈/sub〉O nanosquares were first employed as template to synthesize YVO〈sub〉4〈/sub〉:Ln luminescent crystallites (Ln = Eu, Sm, and Dy) via hydrothermal nanoconversion in the presence of NH〈sub〉4〈/sub〉VO〈sub〉3〈/sub〉. Product properties and the course of phase/morphology evolution were characterized in detail by XRD, SEM, TEM, FT-IR, TG, and optical spectroscopy. It was clearly demonstrated that the nanosquares templated vanadate crystallization, owing to structure similarity, but was accompanied by subsequent dissolution and reprecipitation. The resultant vanadate phosphors, mostly in the form of bundles containing platelike and fibrous crystallites, exhibited strong red emission at ∼618 nm for Eu〈sup〉3+〈/sup〉, orange-red emission at ∼604 nm for Sm〈sup〉3+〈/sup〉 and greenish yellow emission at ∼575 nm for Dy〈sup〉3+〈/sup〉 upon exciting the VO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 ligand. Dehydration at 500 °C further improved the emission by ∼2.5 times for Eu〈sup〉3+〈/sup〉 and ∼1.5 times for Sm〈sup〉3+〈/sup〉 and Dy〈sup〉3+〈/sup〉. The Eu〈sup〉3+〈/sup〉 (5 at%), Sm〈sup〉3+〈/sup〉 (1 at%) and Dy〈sup〉3+〈/sup〉 (1 at%) activators were analyzed to have quantum yields of ∼48, 9 and 16% and color coordinates of around (0.65, 0.33), (0.60, 0.39) and (0.38, 0.43) for their luminescence, and fluorescence lifetimes of ∼1.52, 1.40 and 0.89 ms for their dominant emissions, respectively. It is also interesting to find out that replacing only 15% of the total OH〈sup〉−〈/sup〉 and NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 anions in the template by VO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉 produced ∼20 times stronger Eu〈sup〉3+〈/sup〉 luminescence, indicating that VO〈sub〉4〈/sub〉〈sup〉3-〈/sup〉→ Eu〈sup〉3+〈/sup〉 energy transfer is very efficient. The protocol would be extendable to other types of functional rare-earth compounds.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339719-fx1.jpg" width="245" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Chunmu Guo, Qinghua Tian, Li Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nanostructure of titanium dioxide (TiO〈sub〉2〈/sub〉) has gained extensive attention in anode material field of lithium-ion batteries (LIBs) owing to its outstanding structure stability and improved safety over graphite. Herein, facilely controllable synthesis of interestingly spindle TiO〈sub〉2〈/sub〉 nanograins has been achieved by a one-pot hydrothermal and subsequent calcination approach, it is demonstrated that the grain size has a great effect on the electrochemical lithium storage kinetics of as-synthesized TiO〈sub〉2〈/sub〉 nanograins. As a result, the as-prepared TiO〈sub〉2〈/sub〉-0.05M with much smaller size exhibits greatly improved lithium storage performance, delivering a capacity of 120.5 mAh g〈sup〉−1〈/sup〉 after even 1000 cycles.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Xi Cheng, Shi Wei Xu, You Ming Lu, Shun Han, Pei Jiang Cao, Fang Jia, Yu Xiang Zeng, Xin Ke Liu, Wang Ying Xu, Wen Jun Liu, De Liang Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Zn〈sub〉1-x〈/sub〉Cd〈sub〉x〈/sub〉O films with different Cd contents obtained by controlling the growth oxygen pressure (O〈sub〉p〈/sub〉) were deposited on both c-sapphire (Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) substrates and p-GaN substrates, by means of the pulsed laser deposition (PLD) method. Photoluminescence (PL) measurement revealed that the variation of O〈sub〉p〈/sub〉 influenced the amount of Cd doping into Zn〈sub〉1-x〈/sub〉Cd〈sub〉x〈/sub〉O films deposited on Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, leading tunable luminescence from the ultraviolet (UV) to blue emission extended to the green band. Then all the fabricated n-Zn〈sub〉1-x〈/sub〉Cd〈sub〉x〈/sub〉O/p-GaN heterojunction possessed good ohmic contacts and exhibited typical rectifying characteristic of the diode. Indeed, the high luminescence from the ZnCdO layer could be attained by inserting a MgO insulator to the heterojunction interface. The fabrication of tunable n-Zn〈sub〉1-x〈/sub〉Cd〈sub〉x〈/sub〉O/p-GaN heterojunction light-emitting diodes is available which was supported by the results of electroluminescence (EL) experiment.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Dina V. Deyneko, Ivan V. Nikiforov, Bogdan I. Lazoryak, Dmitry A. Spassky, Ivan I. Leonidov, Sergey Yu. Stefanovich, Daria A. Petrova, Sergey M. Aksenov, Peter C. Burns〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel red emitting phosphors Ca〈sub〉8〈/sub〉MgSm〈sub〉1–〈em〉х〈/em〉〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉7〈/sub〉:〈em〉x〈/em〉Eu〈sup〉3+〈/sup〉 with whitlockite-type structure were prepared by a high temperature solid-state reaction in air. Powder X-ray diffraction (PXRD), photoluminescence spectra, and fluorescence decay were used to characterize the structure and luminescence properties. All samples were found to have the expected rhombohedral structure with 〈em〉R〈/em〉〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mn〉3〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉〈em〉c〈/em〉 space group. The non-polar space group is also confirmed by a photoluminescence study. This space group allows forbidden transitions for Eu〈sup〉3+〈/sup〉. The presence of only one Shtark component in 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉–〈sup〉7〈/sup〉F〈sub〉0〈/sub〉 confirms the presence of only one non-equivalent site containing Eu〈sup〉3+〈/sup〉 ions. The high intensity of the transition ratio 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉–〈sup〉7〈/sup〉F〈sub〉2〈/sub〉/〈sup〉5〈/sup〉D〈sub〉0〈/sub〉–〈sup〉7〈/sup〉F〈sub〉1〈/sub〉 establishes the strongly disordered environment of the Eu〈sup〉3+〈/sup〉 ions. Thus, 〈em〉M〈/em〉1–〈em〉M〈/em〉3 sites in the host matrix are occupied by Ca〈sup〉2+〈/sup〉, Sm〈sup〉3+〈/sup〉, and Eu〈sup〉3+〈/sup〉 ions, whereas 〈em〉M〈/em〉5 is fully occupied by Mg〈sup〉2+〈/sup〉. The optimal concentration was found with 〈em〉x〈/em〉 = 0.75 in Ca〈sub〉8〈/sub〉MgSm〈sub〉1–〈em〉х〈/em〉〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉7〈/sub〉:〈em〉x〈/em〉Eu〈sup〉3+〈/sup〉 phosphors. The emitting of Sm〈sup〉3+〈/sup〉 was depressed due to the high intensity of Eu〈sup〉3+〈/sup〉 luminescence; however, the contribution of Sm〈sup〉3+〈/sup〉 is manifested in the energy transfer process and shift of CIE coordinates. Furthermore, the CIE chromaticity coordinate of 〈em〉as-prepared〈/em〉 Ca〈sub〉8〈/sub〉MgSm〈sub〉0.25〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉7〈/sub〉:0.75Eu〈sup〉3+〈/sup〉 (〈em〉x〈/em〉 = 0.650; 〈em〉y〈/em〉 = 0.345) is close to the standard red-emitting point (〈em〉x〈/em〉 = 0.67, 〈em〉y〈/em〉 = 0.33). The experimental data indicate that Ca〈sub〉8〈/sub〉MgSm〈sub〉1–〈em〉х〈/em〉〈/sub〉(PO〈sub〉4〈/sub〉)〈sub〉7〈/sub〉:〈em〉x〈/em〉Eu〈sup〉3+〈/sup〉 upon excitation by near-UV radiation is a promising red phosphor for white-light-emitting diodes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339999-fx1.jpg" width="131" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Wanwu Ding, Chen Xu, Xingang Hou, Xiaoyan Zhao, Taili Chen, Wenjun Zhao, Tiandong Xia, Jisen Qiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The new type of Al-Ti-C-La master alloy was prepared by commercial pure Al, Ti powder, graphite powder, Al powder and La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 powder by aluminum melt in-situ reaction method. The microstructure and the effect on commercial pure aluminum of Al-Ti-C-La master alloy have been studied by means of X-ray diffraction (XDR), scanning electron microscopy (SEM) equipped with energy-dispersive spectrometry (EDS). The synthesis thermodynamics and kinetics of Al-Ti-C-La master alloy were analyzed. The experiment shows that Al-Ti-C-La master alloy is composed of Al, Al〈sub〉3〈/sub〉Ti, TiC and Ti〈sub〉2〈/sub〉Al〈sub〉20〈/sub〉La. The refining performance of the prepared Al-Ti-C-La master alloy is obviously better than that of Al-Ti-C master alloy when the addition of rare earth oxide La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 is 10 wt% and the preparation temperature is 930 °C. The analysis of thermodynamic calculation and the process of kinetics demonstrate that, in the preparation process of Al-Ti-C-La master alloy, firstly, Al reacts with Ti to produce Al〈sub〉3〈/sub〉Ti, C reacts with Ti and Al〈sub〉3〈/sub〉Ti to form TiC based on the aluminothermy reaction. Rare earth oxide La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and C powder react with Ti powder and O〈sub〉2〈/sub〉 in the air occur to generate CO, TiC, [La] atoms and LaC〈sub〉2〈/sub〉. [La] atoms adsorb on the surface of Al〈sub〉3〈/sub〉Ti to form the new rare earth compounds Ti〈sub〉2〈/sub〉Al〈sub〉20〈/sub〉La.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Changmeng Huan, Xinyue Zhao, Xiudi Xiao, Yuan Lu, Shuai Qi, Yongjun Zhan, Lingzhi Zhang, Gang Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, the V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles (NPs) with ultrathin carbon shells were synthesized by a facile solvothermal process. The V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 NPs were about 30 nm and contained a carbon shell of about 2 nm thick. The V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 NPs were homogeneously dispersed and loosely packed. When used as anode material, the V〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 core-shell NPs showed a reversible capacity up to 525 mA h g〈sup〉−1〈/sup〉 at 200 mA g〈sup〉−1〈/sup〉 over 200 cycles with good cycle stability and rate capability. The excellent electrochemical performance promotes its practical application in lithium-ion batteries.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Honghong Jin, Guang Sun, Bo Zhang, Na Luo, Yanwei Li, Long Lin, Hari Bala, Jianliang Cao, Zhanying Zhang, Yan Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel chain-like nanostructure of Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 was successfully prepared via a facile and reliable oxalate sacrificial template route, in which coralloid cobalt oxalate (CoC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉·2H〈sub〉2〈/sub〉O) precursor was first obtained through a room-temperature precipitation method and then used as sacrificial template to prepare Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 by annealing at 500 °C. Au nanoparticles-decorated Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanochains were also prepared by soaking the CoC〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 precursor in Au〈sup〉+〈/sup〉 solution before the annealing process. The prepared samples were characterized by XRD, FESEM, TEM, and N〈sub〉2〈/sub〉 adsorption-desorption. Results indicated that the pure and Au-decorated Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanochains were constructed by several end-to-end connected nanoparticles, and their specific surface areas were 28.42 m〈sup〉2〈/sup〉/g and 37.39 m〈sup〉2〈/sup〉/g, respectively. The gas sensing properties of the prepared samples were tested and compared. It was found that after being functionalized with Au nanoparticles, the Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanochains showed an improved TEA sensing performance, such as lower optimal working temperature, higher response, and faster response and recover speed. In addition, the Au/Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 sensor can also give a good linearity in the TEA concentration range from 10 to 200 ppm and considerable stability within 7 weeks, suggesting its potential application for quantitative detection of TEA. The improved gas sensing mechanism of the Au/Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanochain was discussed.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): V.A. Lysenko〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A modified version of the Sb-Sn phase diagram was proposed that includes both Sb〈sub〉2〈/sub〉Sn〈sub〉3〈/sub〉 and Sb〈sub〉3〈/sub〉Sn〈sub〉4〈/sub〉 compounds. Based on this modification, phase equilibria in the In-Sb-Sn system were calculated using a thermodynamic modeling approach. Thermodynamic models for the ternary liquid phase and solid solutions (SbSn) and (Sb〈sub〉2〈/sub〉Sn〈sub〉3〈/sub〉) were developed. The isopleths 〈em〉x〈/em〉〈sub〉Sn〈/sub〉 = 0.2, 0.5, 0.8, vertical sections 〈em〉x〈/em〉〈sub〉In〈/sub〉/〈em〉x〈/em〉〈sub〉Sb〈/sub〉 = 3:1, 1:1, 1:3, liquidus surface projection, and isothermal section at 473 K were calculated.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Hongyi Gao, Mengyi Jia, Keyi Dong, Liwen Xing, Xiao Chen, Dandan Jia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A Sisal-Like TiO〈sub〉2〈/sub〉/Graphene-Like Carbon Sheets (SL-TiO〈sub〉2〈/sub〉/GLCSs) composite was fabricated via a facile one-pot self-assembling route at a two-phase interface. The ingenious P123 was introduced to serve a dual function of carbon precursor and structure-directing agent, which first assembled at the water/oil interfaces and subsequently was in situ carbonized to GLCSs. Then the sisal-like TiO〈sub〉2〈/sub〉 grew gradually on the GLCSs along the preferred direction. This process shows several advantages such as simple processes, mild condition, low cost and good combination of SL-TiO〈sub〉2〈/sub〉 and GLCSs. The combination of SL-TiO〈sub〉2〈/sub〉 with GLCSs significantly helps the adsorption of substrates as well as promotes electron-hole pair separation, exhibiting good photocatalytic activity towards degradation of methylene blue (MB) compared to the pristine SL-TiO〈sub〉2〈/sub〉 and commercial P25. This strategy opens up new perspectives for fabricating novel composites of nanooxides/GLCSs.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Zhennan Liu, Naiqin Zhao, Chunsheng Shi, Fang He, Enzuo Liu, Chunnian He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three-dimensional (3D) carbon networks decorated with Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles as lightweight and broadband electromagnetic (EM) wave absorber were 〈em〉in-situ〈/em〉 prepared via a simple and large-scale method, combining freeze-drying and high-temperature calcination processes. SEM and TEM results show that 3D carbon network/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 (3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉) composites have interconnected 3D porous carbon networks with submicrometer-sized macropores, and the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 nanoparticles are distributed uniformly on the 3D carbon networks. The EM wave absorption performance of 3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 can be tuned by changing Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 contents. The 3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 with about 38.2 wt% Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 exhibits excellent lightweight and broadband EM wave absorption property. The effective absorption bandwidth can reach up 5.95 GHz (11.2–17.15 GHz) at the thickness of 3.0 mm with only 20 wt% filler loading. The minimum RL of −37.8 dB was obtained at 6.95 GHz. The excellent EM wave absorption capability of 3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 can be ascribed to good impedance matching, strong dielectric loss ability and unique 3D porous structure. This work demonstrates that the 3DC/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 with light weight, broad absorption bandwidth and large-scale production potential can be a promising absorber for practical application.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339768-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Dan Zhou, Li-Ping Xue, Ning Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transition metal phosphides are promising anode materials for next-generation rechargeable sodium-ion batteries due to the high theoretical capacities. However, the inherent low conductivity and large volume expansion of transition metal phosphides during the repeated sodiation/desodiation process critically hinder their practical applications. Herein, we immobilize Ni〈sub〉2〈/sub〉P nanoparticles robustly in porous carbon sheet networks via the pyrolysis and 〈em〉in-situ〈/em〉 phosphatization of poly(acrylic acid)-Ni(NO〈sub〉3〈/sub〉)〈sub〉2〈/sub〉 gel. The resulted porous network structure, high conductivity, robust chemical combination and space confinement effect of the Ni〈sub〉2〈/sub〉P-carbon composite offer the electrode not only rigid structural stability for volume expansion over long-term cycling, but also large specific capacity and fast Na〈sup〉+〈/sup〉/electrons transfer kinetics. As a consequence, the composite delivers a large initial discharge capacity (932 mAh g〈sup〉−1〈/sup〉 at 50 mA g〈sup〉−1〈/sup〉), a high rate capability (77 mAh g〈sup〉−1〈/sup〉 at 3500 mA g〈sup〉−1〈/sup〉), as well as a significantly enhanced long cycle-life (146 mAh g〈sup〉−1〈/sup〉 after 1500 cycles at 500 mA g〈sup〉−1〈/sup〉). The excellent Na-storage performance makes the synthesized Ni〈sub〉2〈/sub〉P-carbon composite a sound anode material for advanced rechargeable SIBs.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Yu Jun Yang, Weikun Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This work presents a novel method for the self-assembly of reduced graphene oxide (rGO) on nickel foam (NF) and the subsequent electrodeposition of hierarchical Ni-Co double hydroxide (NiCo-DH) nanosheets (NS) on rGO as a supercapacitor electrode. The self-assembly of rGO on NF is achieved by the direct reduction of graphene oxide at 50 °C. NF is not only used as the support of rGO but also the reducing agent for the reduction of GO. As the battery-type electrode material for supercapacitor, NiCo-DH supported on rGO modified NF (Ni-Co DHNS@rGO-NF) displays an ultrahigh areal capacity of 5.820 C cm〈sup〉−2〈/sup〉 at 20 mA cm〈sup〉−2〈/sup〉, a 100% coulombic efficiency and a 78% capacity retention after 2000 cycles at 100 mA cm〈sup〉−2〈/sup〉. An hybrid supercapacitor (HSC) is also assembled based on Ni-Co DHNS@rGO-NF as the positive electrode and active carbon (AC) as the negative electrode. The ASC exhibits a prominent energy density of 45.83 Wh kg〈sup〉−1〈/sup〉 at a high power density of 396.15 W kg〈sup〉−1〈/sup〉. The excellent electrochemical performance is attributed to the large surface area of the hierarchical NiCo-DH nanosheets array and the synergistic effect between Ni-Co DHNS and rGO.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Kodai Maeda, Satoshi Suzuki, Kyosuke Ueda, Tomonori Kitashima, Somesh Kr. Bhattacharya, Ryoji Sahara, Takayuki Narushima〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper reports the first study of the oxidative behavior of Si-containing Ti-6Al-4V alloys in air. The alloys were studied in the temperature range 910–1210 K for a maximum period of 518.4 ks, and their tensile properties at room temperature are reported. The addition of Si decreased the total mass gain during oxidation and enlarged the region in which the mass gain obeyed the parabolic rate law. The oxide scale mainly consisted of rutile and α-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 phases. The results of the XPS analysis suggest that in rutile, Si exists as both Si〈sup〉4+〈/sup〉 ions and SiO〈sub〉2〈/sub〉. First-principles calculations indicated that Si〈sup〉4+〈/sup〉 ions stably dissolved into the interstitial sites in rutile, which suppresses oxygen migration through rutile by decreasing the number of oxygen vacancies, thereby inhibiting oxide scale formation. The reaction layer consisting of Ti〈sub〉3〈/sub〉Al and α″ phases on Ti-1mass% Si alloy suppressed the dissolution of oxygen into the substrate, i.e., α-case formation. The ratio of mass gain in α-case formation to total mass gain during oxidation at 1010 K and 1110 K ranged from 0.077 to 0.42. The addition of Si to the Ti-6Al-4V alloy was effective in improving both its oxidative resistance and tensile strength.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339653-fx1.jpg" width="292" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Joo Sung Kim, Young Been Kim, Seung Ki Baek, Young Dae Yun, Sung Hyeon Jung, Sung Woon Cho, Cheol Hyoun Ahn, Hyung Koun Cho〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To maximize the advantages of thin-film-based TiO〈sub〉2〈/sub〉 photoelectrodes for transparent self-driven photoelectrochemical (PEC) reactions, we artificially designed a compositionally graded bi-layer compounds consisting of SnO〈sub〉2〈/sub〉 and TiO〈sub〉2〈/sub〉. This structure exhibited a vigorous photocatalytic activity, sufficient photovoltage, and long-term stability. A compositionally graded SnO〈sub〉2〈/sub〉/TiO〈sub〉2〈/sub〉 interface (G-SnTiO) for improved charge transport efficiency and sufficient photovoltage was derived by a solution process using simultaneous sintering after sol-gel coating the SnO〈sub〉2〈/sub〉/TiO〈sub〉2〈/sub〉 layers; the structure was verified by various analysis methods, such as transmission electron microscopy, energy dispersive X-ray spectroscopy, and secondary ion mass spectrometry. The high performance from the G-SnTiO structure was attributed to an effective charge separation from the formation of a heterostructure interface with reduced defects, resulting in a sufficient photovoltage for self-driving. To construct self-driven and sustainable overall cells without an external potential and considerable reduction in transparency, two-electrode PEC cells with a G-SnTiO photoanode and Cu〈sub〉2〈/sub〉O photocathode were fabricated with a regular hexahedron shape for a color degradation test of methylene-blue-incorporated electrolytes, and exhibited enhanced purification speed and robust durability.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339379-fx1.jpg" width="335" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Usama Bin Humayoun, Seok Bin Kwon, Syed Kamran Sami, Dae-Ho Yoon〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Among various red phosphors, Mn〈sup〉4+〈/sup〉 activated fluoride hosts have received much attention due to their blue excitability and intense red emission. In this study we report a novel (NH〈sub〉4〈/sub〉)〈sub〉3〈/sub〉AlF〈sub〉6〈/sub〉:Mn〈sup〉4+〈/sup〉 phosphor, synthesized through a facile synthesis process avoiding high quantities of highly toxic HF acid. The synthesized host exhibit cubic structure in F-4 3m space group, with plenty of [AlF〈sub〉6〈/sub〉]〈sup〉3+〈/sup〉 octahedral sites. When activated with Mn〈sup〉4+〈/sup〉 the crystal structure is retained and the material exhibits characteristic excitation bands with maximum around 469 nm and intense red emission around 631 nm. Furthermore, the thermal gravimetric analysis revealed the stability of composition up to 250 °C. The phosphor however exhibits high sensitivity to increased temperature and showed sharp quenching of luminescence at elevated temperatures.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Rui Du, Du Yuan, Fei Li, Dongcheng Zhang, Shusen Wu, Shulin Lü〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study intends to offer a depth understanding on controlling the morphology of eutectic Mg〈sub〉2〈/sub〉Si by adding in-situ TiB〈sub〉2〈/sub〉 particles into 10 〈em〉wt〈/em〉% Mg〈sub〉2〈/sub〉Si/Al composite. The evolution of the microstructure and mechanical properties of Mg〈sub〉2〈/sub〉Si/Al composites with different TiB〈sub〉2〈/sub〉 particles addition from 1 〈em〉wt〈/em〉% to 5 〈em〉wt〈/em〉% is investigated and the mechanism is also discussed. The results show that coarse eutectic Mg〈sub〉2〈/sub〉Si phase can be refined and modified with the addition of TiB〈sub〉2〈/sub〉 particles, and the lattice coherence between them is also confirmed. Besides, the addition of TiB〈sub〉2〈/sub〉 particles can greatly enhance multiple mechanical properties of composites at the same time. With 5% TiB〈sub〉2〈/sub〉 particles addition, the modulus, yield strength and elongation of composites are improved 11%, 59% and 141% respectively compared with Mg〈sub〉2〈/sub〉Si/Al composites. Moreover, different addition of TiB〈sub〉2〈/sub〉 particles changes gradually the fracture behavior of composites from brittle fracture to quasi-cleavage fracture, and finally to entirely ductile behavior.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): S.S. Mani Prabu, H.C. Madhu, Chandra S. Perugu, K. Akash, R. Mithun, P. Ajay Kumar, Satish V. Kailas, Manivannan Anbarasu, I.A. Palani〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Welding of shape memory alloys without deterioration of shape memory effect could vastly extend their applications. To retain shape memory behavior, a solid-state welding technique called friction stir welding was employed in this study. Austenitic NiTi alloy sheets of thickness 1.2 mm were joined at tool rotational speeds of 800, 1000, and 1200 rpm. Due to dynamic recrystallization, the grain refinement has occurred in the weld region. The tensile testing has shown superelastic plateau for the welds at 800 and 1000 rpm. The phase transformation behavior of different weld regions was studied in detail using differential scanning calorimeter. A marginal drift in transformation temperatures was observed in the weld. To understand the drift in phase transformation temperatures, finite element analysis was carried out with focus on temperature distribution during welding. Finally, time-dependent shape recovery of a FSW welded joint was studied and it was found that the original position was completely recovered after 27 s at a temperature of 65 °C.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881833874X-fx1.jpg" width="437" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Matthias Stacher, Gabriel R. Reisinger, Klaus W. Richter〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Phase equilibria of Au-Ni-Si were investigated in the isothermal section at 700 °C using a combination of powder X-ray diffraction and quantitative phase analysis by SEM-EDX. Four vertical sections of the phase diagram at 10 at.% Au and at 15, 30 and 60 at.% Ni were studied by DTA. These data were combined with isothermal sections at 320° and 500° published earlier to develop a ternary reaction scheme and a liquidus surface projection. Fifteen ternary invariant reactions, a three-phase field maximum and a critical tie-line are proposed. The observed phase diagram is discussed regarding the possible use of Au-Si liquids for transient liquid phase (TLP) soldering of Nickel.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Yong Zhang, Jinming Guo, Jianghua Chen, Cuilan Wu, Karoline Sophie Kormout, Pradipta Ghosh, Zaoli Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bulk nanocrystalline alloys usually possess enhanced properties than their coarse-grained counterparts. Here, first-principles calculations and aberration-corrected transmission electron microscope (TEM) were employed to investigate the atomic-scale deformation mechanism of Cu-based alloys. The effect of alloying element concentration and temperature-induced solute distribution on the unstable stacking fault energy (γ〈sub〉usf〈/sub〉), stable stacking fault energy (γ〈sub〉isf〈/sub〉) and unstable twin fault energy (γ〈sub〉utf〈/sub〉) were calculated using a Fermi–Dirac distribution of solutes for 42 binary Cu-X alloys. At medium temperature (〉200 K) or low solute concentrations (〈15 at.%), the stacking fault energies calculated from the Fermi–Dirac model accord well with the available experimental and theoretical results. The deformation mechanism was then evaluated by α = γ〈sub〉isf〈/sub〉/γ〈sub〉usf〈/sub〉 and β = γ〈sub〉utf〈/sub〉/γ〈sub〉usf〈/sub〉, smaller α (β) favors an easier formability of extended dislocations (twins). Most subgroup VI-VIII metals in the periodic table can slightly increase the γ〈sub〉usf〈/sub〉, γ〈sub〉isf〈/sub〉 and γ〈sub〉utf〈/sub〉 of Cu, and have almost no influence on α and β. While main group and subgroup II-V elements can decrease γ〈sub〉usf〈/sub〉, γ〈sub〉isf〈/sub〉 and γ〈sub〉utf〈/sub〉 as well as the values of α and β. For alloying elements of Pd, Ag, Pt and Au, the values of α and β increase, suggesting a tendency of deformation mechanism from extended dislocations to full dislocations. Furthermore, high-resolution TEM (HRTEM) images of four representative nanocrystalline alloys (pure Cu, Cu-Fe, Cu-Ag and Cu-Zn) corroborates the prodiction with α and β as well as the empirical twinnability. The α and β remain almost the same as that of pure Cu when alloyed with Fe while they decrease with Zn, and the extended dislocations and twins were commonly observed for Cu, Cu-Fe and Cu-Zn. The α and β increased with Ag addition although the γ〈sub〉isf〈/sub〉 decreased, and the extended dislocations were barely observed for Cu-Ag sample. The theoretical and microstructural correlation provides insights into the deformation mechanism of Cu-based alloys.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Yongju Yoo, Yun Chan Kang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 materials based on intercalation reactions have been extensively studied as anode materials for lithium-ion batteries. Mesoporous Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 microspheres with narrow size distribution are the ideal structure for achieving a high volumetric capacity. Mesoporous filled- and yolk-shell-structured (reported for the first time) Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 microspheres are synthesized using a highly porous carbon template. The NbSe〈sub〉3〈/sub〉-C composite transforms into yolk-shell-structured Nb〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 microspheres by a one-step oxidation process. The filled microspheres having ultrafine crystallite size and high mesopore volume show better cycling and rate performances than the yolk shell microspheres. The discharge capacity of the filled microspheres at a current density of 1 A g〈sup〉−1〈/sup〉 is 124 mA h g〈sup〉−1〈/sup〉 in the 5000〈sup〉th〈/sup〉 cycle, and the capacity retention in the second cycle is 76%. The discharge capacity of the filled microspheres decreases by approximately 26% from 171 mA h g〈sup〉−1〈/sup〉 to 127 mA h g〈sup〉−1〈/sup〉 when the current density increases from 0.5 A g〈sup〉−1〈/sup〉 to 10 A g〈sup〉−1〈/sup〉. Particularly, the volumetric capacity of the filled microspheres at a high current density of 10 A g〈sup〉−1〈/sup〉 is 2.3 times higher than that of the yolk-shell-structured microspheres (filled ≈ 11.5 mA h cc〈sup〉−1〈/sup〉 vs. yolk ≈4.9 mA h cc〈sup〉−1〈/sup〉).〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Dunya M. Babanly, Ziya S. Aliev, Qorkhmaz M. Huseynov, Salim M. Asadov, Solmaz N. Mustafaeva, Dilgam B. Tagiyev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The phase equilibria in the ternary Tl-S-I system were investigated experimentally by means of powder X-ray diffraction (PXRD) and differential thermal analysis (DTA). Five isopleth sections, liquidus surface projection and room temperature isothermal section were constructed based on experimental data. 〈em〉dc〈/em〉-and 〈em〉ac〈/em〉-electric properties of the TlS and Tl〈sub〉6〈/sub〉SI〈sub〉4〈/sub〉 crystals were studied within the temperature and frequency ranges from 120 K to 300 K and from 50 kHz to 35 MHz, respectively. The hopping mechanism for charge transfer over the localized states near the Fermi level was established at low temperatures and high frequencies for these compounds. The density and energy scatter of the states which are located in the vicinity of the Fermi level as well as the average time and distances of jumps were estimated for the title compounds.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Marietta Seifert, Gayatri K. Rane, Siegfried B. Menzel, Steffen Oswald, Thomas Gemming〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A sufficient oxidation resistance of RuAl thin films is crucial for their application in high temperature sensors e.g. based on the surface acoustic waves principle. To improve the high temperature stability, an Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 or SiO〈sub〉2〈/sub〉 cover layer is added to protect the films from oxidation especially for application in air. The covered RuAl films are annealed at temperatures up to 900 °C under high vacuum and in air for 10 h. X-ray diffraction, cross section imaging and Auger electron spectroscopy are applied to reveal the suitability of the cover layers as oxidation barrier. While there is hardly any difference between the samples with or without cover layer after annealing under high vacuum, only the samples with SiO〈sub〉2〈/sub〉 cover are stable up to 800 °C in air.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339525-fx1.jpg" width="483" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): O.V. Maksakova, S. Simoẽs, A.D. Pogrebnjak, O.V. Bondar, Ya.O. Kravchenko, T.N. Koltunowicz, Zh.K. Shaimardanov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Multilayered ZrN/CrN coatings were produced by the cathodic arc physical vapor deposition (CA-PVD). Morphology, element distribution, structural and thermal properties were investigated. Microhardness and nanoindentation tests were conducted to study the mechanical properties of the coatings. The experimental results of scanning electron microscopy (SEM) revealed the cellular microrelief of the surface and well-defined multilayered architecture of the coatings. Energy dispersive spectroscopy (EDS) provided the chemical characterization of the coatings and revealed the formation of stoichiometric composition in coatings. X-ray diffraction (XRD) studies showed that (200) and (111) plane reflections of ZrN and Cr〈sub〉2〈/sub〉N phases, correspondingly, were with maximum intensity. Transmission electron microscopy (TEM) analysis revealed that the films comprise of nanometric equiaxed grains with average sizes from 12.8 to 15.1 nm for ZrN layers and from 14.5 to 28.1 nm for CrN layers. The high-temperature heat treatment caused exothermic and endothermic reactions, which were mainly attributed to the improvements or disordering of the coatings' structure, consequently. The highest values of microhardness (4966HV0.025) and nanohardness (24.58 GPa) were obtained for the sample with a bilayer thickness of 732 nm, the average crystallite size of 13.3 nm and nitrogen content of 49 at%. Experimental results indicated that deposited composites can be effectively used in the production of industrial tools, implements for cutting etc.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Manisha Kumari, Shrabani Mondal, Prashant K. Sharma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The drug loading and release properties of Eu〈sup〉3+〈/sup〉 doped GdPO〈sub〉4〈/sub〉 nanoparticles (NPs) were studied using a simple electrochemical protocol in an 〈em〉in-vitro〈/em〉 environment, taking acetaminophen as a model drug. The electrochemical monitoring of drug release was also validated with absorption spectroscopy technique. For this purpose, dual stimuli (pH and temperature) responsive monoclinic mesoporous GdPO〈sub〉4〈/sub〉 nanoparticles of size ∼22 nm were synthesized by a simple hydrothermal method. Crystal structure, size, shape, morphology, porosity, optical property and magnetic properties of the obtained product were studied by different characterization techniques. Successful loading of drug in NPs was investigated by Fourier transform infrared spectroscopy (FT-IR). Photoluminescence (PL) measurement shows orange-red color emission corresponding to 〈sup〉5〈/sup〉D〈sub〉0〈/sub〉→〈sup〉7〈/sup〉F〈sub〉2〈/sub〉 transitions of Eu〈sup〉3+〈/sup〉 ions. The vibrating sample magnetometer (VSM) measurements showed negligible hysteresis in both samples, suggesting retention of the superparamagnetic behavior of GdPO〈sub〉4〈/sub〉 NPs. The high loading capacity of 79% and encapsulation efficiency of 83% is observed when acetaminophen, an anti-fever drug, was loaded on these mesoporous GdPO〈sub〉4〈/sub〉 NPs. The drug was attached on NPs surfaces via absorption, without any special surface modification. During drug release studies, a spontaneous and smooth release from these mesoporous NPs was observed at a moderate-high temperature (37 °C) and low pH (pH 5) with no sign of burst release. These nanoparticles were capable of targeting and specific release of the loaded drug in response to pH and temperature and hence may serve as a potential drug carrier for 〈em〉in-vivo〈/em〉 applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339604-fx1.jpg" width="275" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Shixiang Zuo, Zhan Liu, Wenjie Liu, Xiazhang Li, Zhongyu Li, Chao Yao, Qun Chen, Yongsheng Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oriented rutile TiO〈sub〉2〈/sub〉 nanorod arrays (TiO〈sub〉2〈/sub〉 NRA) were elaborately grown on the conductive mica (C-mica) with Sb-SnO〈sub〉2〈/sub〉 seed crystal by a hydrothermal strategy to achieve TiO〈sub〉2〈/sub〉 NRA/C-mica composites. The as-obtained samples were characterized by X-ray diffraction, field emission scanning electron microscope, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy and photo-electrochemical measurements. Compared with TiO〈sub〉2〈/sub〉 NP/mica, TiO〈sub〉2〈/sub〉 NRA/C-mica coated film exhibits more excellent physical barrier ability in the dark, and an enhanced photo-induced current density as well as a more negative photo-potential shift in the light, indicating remarkable photo-cathodic protection for 304 stainless steel (304SS). The distinctive 1D-2D architecture of TiO〈sub〉2〈/sub〉 NRA/C-mica facilitates the transmission and separation of photo-induced electron-hole pairs. Furthermore, it's the first time that the TiO〈sub〉2〈/sub〉 NRA/C-mica hybrid film is found to possess continuous and stable cathodic protection for the 304SS over a long period in the dark.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881834009X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Baochen Wang, Ziyao Wang, Yangai Liu, Tao Yang, Zhaohui Huang, Minghao Fang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Crystal structure tailoring is a commonly used method for tuning the luminescence of phosphors. This study mainly aims at luminescent spectra tuning of Sr〈sub〉1−〈em〉x〈/em〉〈/sub〉Ba〈sub〉〈em〉x〈/em〉〈/sub〉Al〈sub〉2〈/sub〉Si〈sub〉2〈/sub〉O〈sub〉8〈/sub〉:Eu〈sup〉2+〈/sup〉 phosphors by substitution of Ba for Sr ions. The phase composition was characterized by X-ray powder diffraction and the crystal structure was determined by using the Rietveld refinement method. The excitation and emission spectra, diffuse reflectance spectra, and thermal quenching were also investigated in detail. The results show that Sr〈sub〉1−〈em〉x〈/em〉〈/sub〉Ba〈sub〉〈em〉x〈/em〉〈/sub〉Al〈sub〉2〈/sub〉Si〈sub〉2〈/sub〉O〈sub〉8〈/sub〉:Eu〈sup〉2+〈/sup〉 phosphors can form a series of continuous solid solutions in the range from 0 to 0.75. With the increase in 〈em〉x〈/em〉 value, the emission spectra show an obvious redshift from 415 to 450 nm. The emission redshift plays an important role in enabling Sr〈sub〉1−〈em〉x〈/em〉〈/sub〉Ba〈sub〉〈em〉x〈/em〉〈/sub〉Al〈sub〉2〈/sub〉Si〈sub〉2〈/sub〉O〈sub〉8〈/sub〉:Eu〈sup〉2+〈/sup〉 to be used as a standard blue phosphor for application in white-light-emitting diodes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818340465-fx1.jpg" width="303" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Jia Sun, Qian-Gang Fu, Tao Li, Guang-Peng Zhang, Rui-Mei Yuan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Constituent phases, porosity and residual stress are significant factors influencing the performance of two-dimension (2D) structural components. In present study, these factors with respect to thermally sprayed MoSi〈sub〉2〈/sub〉 based composite were elaborately adjusted through plasma spraying power to investigate the oxidation behavior in medium temperature range of 400–900 °C. By increasing the operation powers, the improved melting degree of feedstock led to the increased metastable phases and the decreased porosity in the MoSi〈sub〉2〈/sub〉 based composite but it did not remarkably affect the residual stress distribution. After the analysis on the medium-temperature oxidation, it can be concluded that the metastable phases and the porosity were principally responsible for the enhanced oxidation resistance of the MoSi〈sub〉2〈/sub〉 based composite. The thermal-sprayed 2D MoSi〈sub〉2〈/sub〉 based composites with large amounts of 〈em〉β〈/em〉 phases and low porosity can achieve the outstanding oxidation resistance in medium temperature range.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Li Jin, Jun Qiao, Lei Hou, Liang Wang, Lin Zhang, Xu Lu, Hongliang Du, Xiaoyong Wei, Yan Yan, Gang Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Perovskite ferroelectric ceramics with 〈em〉T〈/em〉〈sub〉〈em〉m〈/em〉〈/sub〉 (temperature corresponding to maximum dielectric permittivity 〈em〉ε〈/em〉′) around room temperature and high electrostrictive coefficient 〈em〉Q〈/em〉〈sub〉33〈/sub〉 are of interest to the applications in high-precision actuators, since low-hysteresis/non-hysteresis and high strain response can be generated in these materials based on a purely electrostrictive effect. In this work, undoped Ba(Zr〈sub〉0.2〈/sub〉Ti〈sub〉0.8〈/sub〉)O〈sub〉3〈/sub〉 (BZT) and La〈sup〉3+〈/sup〉-doped Ba(Zr〈sub〉0.2〈/sub〉Ti〈sub〉0.8〈/sub〉)O〈sub〉3〈/sub〉 (BLZT) lead-free ferroelectrics were synthesized by solid state reaction method. Their dielectric and ferroelectric properties were investigated systematically with an emphasis on electrostrictive effect. With respect to increase of La〈sup〉3+〈/sup〉 content from 0 to 1%, the 〈em〉T〈/em〉〈sub〉〈em〉m〈/em〉〈/sub〉 of BLZT decreases from 44.5 °C to 14.6 °C, and the diffuseness degree 〈em〉γ〈/em〉 increases from 1.814 to 1.993. A conductive mechanism, which is prominent in undoped BZT, is inhibited drastically by introducing the La〈sup〉3+〈/sup〉 into BZT. A high electrostrictive strain of 0.08% and a low hysteresis 〈em〉η〈/em〉 (〈10%) are obtained simultaneously in 〈em〉x〈/em〉 = 0.25% composition at room temperature. The 〈em〉Q〈/em〉〈sub〉33〈/sub〉 ranges from 0.0377 m〈sup〉4〈/sup〉/C〈sup〉2〈/sup〉 and 0.0537 m〈sup〉4〈/sup〉/C〈sup〉2〈/sup〉. This work not only reports a high electrostrictive effect in BLZT ferroelectrics, but also provides BLZT ceramics with a potential application in high-precision actuators.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Fuwen Yu, Chunjin Hang, Menghui Zhao, Hongtao Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A die-attach material based on an Sn-coated Ni core-shell powder with a high re-melting temperature can be used for high-temperature applications. The outer Sn layers of the Sn-coated Ni particles possess a low melting point of 232 °C and can be completely converted into a Ni〈sub〉3〈/sub〉Sn〈sub〉4〈/sub〉 intermetallic compound with a high re-melting point of 794.5 °C after reflowing at a low temperature of 250 °C for 40 min. This die-attach material exhibits an excellent high-temperature operational capability, with a high shear strength of 40.2 MPa at 500 °C. The coefficient of thermal expansion (CTE) of the reflowed preform is between those of SiC and Cu, which is highly beneficial for mitigating the stress caused by the CTE mismatch between these materials. In addition, the thermal conductivity of the bondline is sufficiently high for heat dissipation during operation.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): José C.S. Filho, Sérgio C. Zilio, Djalmir N. Messias, Viviane Pilla, Anielle C.A. Silva, Noelio O. Dantas, Acácio A. Andrade〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The thermal expansion (〈em〉α〈/em〉) and the thermo-optic (d〈em〉n〈/em〉/dT) coefficients of a phosphate glass dubbed as PANK were simultaneously measured using a single arm double interferometer from 100 to 400 K of the temperature range. An athermal behavior of the optical path difference in a two-beam interferometer was found around 200 K. This result is in agreement with a similar observation carried out applying the Thermal Lens spectrometry (TLS) of Nd-doped PANK glass at ∼180 K. The main difference between these temperature values is ascribed to the sample surface curvature induced by the laser beam in thermal lens measurements. The athermal behavior shows that this glass has the potential for laser applications as an ion host at low temperature, and small changes in the glass composition should be explored to bring this property to room temperature.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339306-fx1.jpg" width="288" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): B.N. Sahoo, S.K. Panigrahi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnesium matrix in-situ composites with hybrid TiC+TiB〈sub〉2〈/sub〉 reinforcement are potential materials for automobile and aerospace applications. It is essential to establish the processing map of such composites as these materials may undergo several thermo-mechanical processes while manufacturing engineering components. In the current work, AZ91 Magnesium matrix TiC+TiB〈sub〉2〈/sub〉 reinforces hybrid in-situ along with its base counterpart were developed and subjected to solutionization followed by peak aging treatment. The safe processing zone for both base and in-situ composite at all heat treatment conditions have been established through processing map based on dynamic materials model (DMM) by conducting hot compression tests at various temperatures (250 °C – 450 °C) and strain rates (0.001 s〈sup〉−1〈/sup〉 – 10 s〈sup〉−1〈/sup〉). Two regions: stable and instable were identified from processing map for all the material conditions. Dynamic recrystallization is the main dominant mechanism in stable region, whereas instable region is characterized by twin and intergranular cracks. To understand the mechanism of hot deformation behavior, activation energy is calculated based on constitutive model for all material conditions. The developed in-situ composite in peak aged condition is found to possess higher activation energy (∼230 kJ/mol) as compared to base alloy (∼126 kJ/mol). A correlation between constitutive model and processing map have been established with an emphasis on their microstructures.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339483-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Pierre Pichat〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Studies of the adsorption and reactions of appropriate molecules are a valuable means to probe active surfaces. This overview deals with the use of nitrogen monoxide – a molecule that has less been utilized than some others as a surface probe – to investigate TiO〈sub〉2〈/sub〉 and TiO〈sub〉2〈/sub〉-containing materials, with or without photo-excitation. It shows that diverse information can be derived from: (1) the infrared spectra of adsorbed NO; (2) the isotopic exchange of N〈sup〉18〈/sup〉O; (3) the formation of N〈sub〉2〈/sub〉O and N〈sub〉2〈/sub〉; (4) the use of NO (or N〈sup〉18〈/sup〉O) in oxidation reactions in place of O〈sub〉2〈/sub〉; and (5) the evaluation of the electron transfer to NO through density functional theory calculations, ultraviolet photoemission spectroscopy, and photoconductance measurements. Valuable knowledge may thus be potentially acquired on: the accessibility and reactivity of surface OH groups, the lability of surface O atoms, the self-cleaning efficacy, the environment and dispersion of TiO〈sub〉2〈/sub〉 in composite materials, the existence of bandgap electronic states, and the electron transfer capacity, depending on the investigation technique employed, the conditions and the type of TiO〈sub〉2〈/sub〉 sample.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118311921-ga1.jpg" width="348" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 30 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): G. Bonura, A.A. Khassin, T.M. Yurieva, C. Cannilla, F. Frusteri, L. Frusteri〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of coprecipitated binary Cu-ZrO〈sub〉2〈/sub〉 catalysts was found to show an interesting activity–selectivity pattern during methanol synthesis from catalytic hydrogenation of carbon oxides (〈em〉P〈/em〉〈sub〉R〈/sub〉, 20–30 atm; 〈em〉T〈/em〉〈sub〉R〈/sub〉, 200–240 °C). The effects of various pre–treatments as well as the copper/zirconia ratio on the structural and chemical properties of these samples were examined. The isoconversional Ozawa-Flynn-Wall method was applied to study the reduction behaviour, while the best fit modelling was used to establish the plausible mechanism of copper reduction. The extent of methanol formation rate was found to be dependent on the structure formed upon catalyst reduction, both in CO and in CO〈sub〉2〈/sub〉 hydrogenation conditions. The pre–calcination of the sample at a temperature as high as 650 °C negatively affected the methanol formation rate under CO hydrogenation conditions, while under the same activation treatment an increased specific activity was observed in CO〈sub〉2〈/sub〉 hydrogenation conditions, although with a minor methanol selectivity, since the rate of the WGS reaction was stronger enhanced. The incorporation of Zn into the catalyst formulation resulted in a visible increasing of the methanol formation rate, owing to the formation of a copper–zinc mixed oxide during calcination, which leads to higher metal dispersion also depressing the methane formation rate.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118307028-ga1.jpg" width="286" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Chuanjun Li, Rui Guo, Shengya He, Weidong Xuan, Xi Li, Yunbo Zhong, Zhongming Ren〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The formation of the microstructures in the hypo- and hypereutectic Al〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Cu alloys in the steady magnetic field (SMF) was investigated using the conventional quenching technique. In comparison with quenched structures without the SMF, the additional bulky phases, i.e. θ-Al〈sub〉2〈/sub〉Cu phase and the supersaturated α solid solution, were found to form in the Al-26 wt%Cu and Al-45 wt%Cu alloys quenched in the SMF, respectively. The temperature measurements showed that the maximum cooling rate of the quenched sample in the SMF was markedly higher than that without the SMF and thus a larger undercooling was obtained in the SMF. The microstructure formation in the SMF can be rationalized using the Al〈img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al〈sub〉2〈/sub〉Cu phase diagram with metastable extensions and the coupled growth zone.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Wenmin Guo, Bin Liu, Yong Liu, Tianchen Li, Ao Fu, Qihong Fang, Yan Nie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Refractory high-entropy alloys (RHEAs) are promising high-temperature structural materials due to their high melting point and extraordinarily high yield strength. However, their industrial application is greatly restricted due to their limited room-temperature ductility. In the present investigation, a ductile and strong single-phase NbTaTiV RHEA was synthesized by powder metallurgy method. Effects of the sintering temperature on the phase formation, microstructural evolution and the mechanical properties of the NbTaTiV RHEA were characterized. The results show that the NbTaTiV RHEA sintered at 1700 °C has an equiaxed single bcc phase microstructure, no obvious porosity and compositional segregation can be observed. The alloy exhibits a relatively high hardness of 510 HV, yield strength of 1.37 GPa, and compressive fracture strength of 2.19 GPa with a high fracture strain of 23% at room temperature. Typical strain softening and steady state flow occur during compressive deformation at high temperatures. During deformation at 1000 °C, the alloy still exhibits high yield strength of 437 MPa with a compression strain over than 40%. The outstanding mechanical properties is mainly attributed to the homogeneous and fine microstructures, and solid solution strengthening effect. It can be concluded that the powder metallurgy is a promising way for preparing ductile RHEAs with outstanding comprehensive mechanical properties.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Thiquynhxuan Le, Qi Wang, A.V. Ravindra, Xiteng Li, Shaohua Ju〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel microwave heating process for the synthesis of zeolite-Y from spent fluid catalytic cracking (SFCC) catalyst has been proposed in this work. The SFCC catalyst is firstly activated in microwave field by acid solution and then used as an aluminum source for the synthesis of zeolite-Y. The activation effect of hydrochloric acid and oxalic acid on the SFCC catalyst, and the synthesis effects of zeolite-Y production from the activated SFCC catalyst under microwave are studied by ICP, XRD, SEM, and N〈sub〉2〈/sub〉 sorption studies. The results show that microwave-assisted acid activation process can facilitate the formation of the active γ-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and as well enhance the crystallinity of zeolite-Y in the SFCC catalyst, which is beneficial for the synthesis of zeolite-Y. Compared with the inactivated SFCC catalyst, the activated SFCC catalyst has a larger specific surface area and a lower contaminated metal content. The specific surface areas of SFCC catalyst after activation by hydrochloric acid and oxalic acid are 197.1 and 113.6 m〈sup〉2〈/sup〉/g, respectively, indicating better activation by hydrochloric acid compared to oxalic acid in the microwave field. The results demonstrate that increasing the synthesis temperature and prolonging the crystallization time favor the growth of zeolite-Y crystal particles, however, zeolite-Y partially transforms into zeolite-P. The priority of different aluminum sources in zeolite-Y synthesis is: hydrochloric acid activated SFCC catalyst 〉 oxalic acid activated SFCC catalyst 〉 inactivated SFCC catalyst. The zeolite-Y having a particle size range of 0.3–1 μm is successfully synthesized from the activated SFCC catalyst at 100 °C for 2 h under microwave at 2 kg/cm〈sup〉2〈/sup〉 pressure and 1000 W power.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Qing Zhou, Yin Du, Yue Ren, Wangwang Kuang, Weichao Han, Haifeng Wang, Ping Huang, Fei Wang, Jian Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Friction and wear are the two most important properties that determine the long-term performances of metallic glasses as much as strength and ductility. With this in mind, a multilayered strategy was proposed to improve the nano-scratching properties of metallic glass thin films and the well-characterized Zr-based metallic glasses were chosen to be the representative model materials in current work. It was found that the metallic glass could exhibit improved wear resistance and reduced friction coefficient if it is made in the form of multilayers. The complexity in the temporal scale of the lateral force signal is investigated, elucidating the inhomogeneous (and homogeneous) shear-banding processes during the nanoscratching process. The statistical and dynamic analyses of the stick-slip behaviors showed a transition from a chaotic to a self-organized critical state in the multilayers, indicating that the hetero-interfaces promote extensive shear band-interface interactions and induce the scratch hardening effect, both of which are responsible to the excellent tribological properties. The current work not only highlights the significant roles of hetero-interfaces in improving the nano-tribological properties but also make the multilayered metallic glass thin films a promising candidate towards structural and functional applications for metallic glasses.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339446-fx1.jpg" width="280" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): P. Sochacka, A. Miklaszewski, M. Jurczyk〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Titanium-based alloys with fine grain structure represent a class of engineering materials that can exhibit a unique combination of properties. This paper presents the structural evolution of the β phase in Ti-x at. % Mo (x = 10, 23, 27, 31 and 35) alloys synthesized by mechanical alloying with different milling times between 15 min and 48 h and powder metallurgical process with cold powder compaction and sintering or interchangeably hot pressing. The binary alloys were characterized by X-ray diffraction, scanning electron microscopy, chemical composition determination as well as density and porosity measurements. The influence of the chemical composition and method of processing on the final microstructure, and mechanical properties of bulk alloys were studied. The mechanically alloyed Ti23Mo, Ti27Mo and Ti31Mo materials upon sintering at 800 °C for 5 min led to the formation of single β type phase alloys. All these β-type alloys have elastic modulus lower than CP microcrystalline α-Ti, but their hardness is nearly 3 times higher (approx: 460 HV〈sub〉0.3〈/sub〉). The present study has demonstrated that these single phase β-type alloys with fine grain microstructure can be fabricated by the application of hot pressing of mechanically alloyed powders at the temperature below α→β transus (800 °C).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881833891X-fx1.jpg" width="145" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Li Wan, Yun-Lai Deng, Ling-Ying Ye, Yong Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The natural ageing effect on artificial ageing kinetics of Al-Zn-Mg alloy has been studied using small angle X-ray scattering, transmission electron microscopy and mechanical testing methods. The results have demonstrated that with 72 hours natural ageing treatment prior to pre-ageing process can inhibit following natural ageing effect. Samples with direct pre-ageing treatment after quenching from solution temperature exhibit significant natural ageing effect subsequently. The strengthening effect is mainly attributed to the formation of fine GP-zones with particle sizes of less than 1 nm. The microstructures characterization has shown that these GP-zones may transform to precursor of η′ precipitate during pre-ageing process if their size reached a critical size. These precursor of η′ precipitate with the size of ∼1 nm–∼1.2 nm are stable at room temperature.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): A. Brzoza, M. Kowalczyk, A. Wierzbicka-Miernik, P. Czaja, W. Maziarz, A. Wójcik, J. Wojewoda-Budka, M. Sikora, J. Dutkiewicz, M.J. Szczerba〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ni-Mn-Ga-Co-Cu melt spun ribbons were investigated in the as-cast and annealed states. The initial microstructure of the ribbons was highly anisotropic along the growing direction and was characterized by three different regions of equiaxed, columnar and dendritic grains. At ambient temperature, the microstructure was composed of two martensitic phases, i.e. non-modulated and seven-layer modulated, and the high temperature L2〈sub〉1〈/sub〉 austenite phase. The stabilization of the austenite phase was a consequence of a strong grain size reduction, especially close to the “contact” side of the ribbons. Subsequent annealing at 823 K triggered atomic ordering, which promoted an improvement in the magnetization. Additional annealing at 1173 K brought about a substantial refinement of the microstructure. The ribbon structure changed to a single non-modulated martensite phase, whereas on a microstructural level, the grains and martensitic plates coarsened considerably. The annealed ribbons resembled oligo-crystalline materials and may cause interest for magnetic field-induced strain applications.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339057-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Priyanka Nehla, Clemens Ulrich, Rajendra S. Dhaka〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report the structural, transport, electronic, and magnetic properties of Co〈sub〉2〈/sub〉FeGa Heusler alloy nanoparticles. The Rietveld refinements of x-ray diffraction (XRD) data with the space group Fm〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mn〉3〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉m clearly demonstrates that the nanoparticles are of single phase. The particle size (D) decreases with increasing the SiO〈sub〉2〈/sub〉 concentration. The Bragg peak positions and the inter-planer spacing extracted from high-resolution transmission electron microscopy image and selected area electron diffraction are in well agreement with data obtained from XRD. The coercivity initially increases from 127 Oe to 208 Oe between D = 8.5 nm and 12.5 nm, following the D〈sup〉−3/2〈/sup〉 dependence and then decreases with further increasing D up to 21.5 nm with a D〈sup〉−1〈/sup〉 dependence, indicating the transition from single domain to multidomain regime. The effective magnetic anisotropic constant behaves similarly as coercivity, which confirms this transition. A complex scattering mechanisms have been fitted to explain the electronic transport properties of these nanoparticles. In addition we have studied core-level and valence band spectra using photoemission spectroscopy, which confirm the hybridization between 〈em〉d〈/em〉 states of Co/Fe. Further nanoparticle samples synthesized by co-precipitation method show higher saturation magnetization. The presence of Raman active modes can be associated with the high chemical ordering, which motivates for detailed temperature dependent structural investigation using synchrotron radiation and neutron sources.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Xin Zhang, Ming Zhang, Tianyu Cui, Jinman Li, Qingsuo Liu, Haibo Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructure and the shape memory effect of Cu-13.0Al-4.0Ni high temperature shape memory alloys doped with different contents of boron (0.25 wt%, 0.5 wt%, 1.0 wt%, and 2.0 wt%) were studied in this paper. According to the obtained results, it was observed that the microstructure and the shape memory effect were sensitive to the addition of boron, and the addition of boron not only enhanced the mechanical properties of the Cu-13.0Al-4.0Ni alloy, but also greatly improved the shape memory effect of the alloy. The fracture of martensite changed from intergranular fracture to transgranular cleavage fracture. In addition, it was found that the highest shape memory effect was achieved by the addition of 0.25 wt% boron.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Sen Gao, Xian Zhang, Qingfeng Zeng, Shiyu Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Crystalline 〈em〉α〈/em〉-TeO〈sub〉2〈/sub〉 was investigated at ambient pressure using 〈em〉ab initio〈/em〉 calculations. The effect of pressure on 〈em〉α〈/em〉-TeO〈sub〉2〈/sub〉 was studied from 0 to 10 GPa. The lattice parameters and elastic constants calculated by LDA and GGA method at 0 GPa both agree with the available theoretical and experiment results. The elastic constants 〈em〉C〈/em〉〈sub〉〈em〉ij〈/em〉〈/sub〉, the bulk modulus 〈em〉B〈/em〉, the shear modulus 〈em〉G〈/em〉, Young's modulus 〈em〉E〈/em〉, and the ductile and brittle character (〈em〉B〈/em〉/〈em〉G〈/em〉) were calculated and examined in detail. It was found that the calculated universal anisotropy index indicated that 〈em〉α〈/em〉-TeO〈sub〉2〈/sub〉 has anisotropy under 0 GPa, and with the pressure increases, its elastic anisotropy increases. Furthermore, from the mechanical stability criteria, it is show that the structure of tetragonal 〈em〉α〈/em〉-TeO〈sub〉2〈/sub〉 is not stable above 5.1 GPa. Finally, the electronic and optical properties were also investigated, and the results show that, on increasing the external pressure, the energy bandgap increases, with the optical spectrum exhibiting anisotropy in the 〈em〉x〈/em〉 and 〈em〉z〈/em〉 directions and a small blue shift under pressure.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Jens Reiser, Andreas Hoffmann, Johannes Hain, Ute Jäntsch, Michael Klimenkov, Jörg Hohe, Tobias Mrotzek〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉This paper describes a systematic analysis of liquid-phase infiltrated molybdenum (Mo) copper (Cu) composites, deformed by various levels, and elucidates the impact of (i) the copper content, and (ii) the rolling reduction on the evolution of the material properties. The rolling-induced change of the thermo-physical properties can be traced back to (ii-a) the evolution of the geometry (viz. the flattening of the molybdenum and the copper phase during rolling) and (ii-b) the evolution of the crystallographic texture.〈/p〉 〈p〉Four infiltrated ingots with a copper content of 23, 39, 48 and 54 vol % were produced. Each ingot was gradually rolled down to a final degree of deformation of 0.5, 1, 1.5, 2 and 2.38, which corresponds to a rolling reduction of 39%, 63%, 78%, 86% and 90%. In summary, four material compositions (23, 39, 48 and 54 vol % Cu) in six conditions (as-infiltrated and five as-rolled conditions) were examined.〈/p〉 〈p〉The evolution of the microstructure is correlated with the evolution of the mechanical and thermo-physical properties such as hardness (HV2), Young's modulus, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mi〉E〈/mi〉〈/mrow〉〈/math〉, electrical conductivity, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈mi〉σ〈/mi〉〈/mrow〉〈/math〉, thermal conductivity, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈mrow〉〈mi〉k〈/mi〉〈/mrow〉〈/math〉, and the coefficient of thermal expansion, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mrow〉〈mi〉α〈/mi〉〈/mrow〉〈/math〉 (CTE, in the range of 350 °C (623 K) – 750 °C (1023 K)).〈/p〉 〈p〉It was found, that the same thermal conductivity can be gained by using either a low copper-content composite that features a low degree of deformation or by using a high copper-content composite that was rolled down to a high degree of deformation.〈/p〉 〈p〉Furthermore, we were able to demonstrate that peculiarities in the CTE-over-T curves can be traced back to the plastic deformation of the copper phase, which is affected by rolling-induced residual stresses and recrystallisation processes during the CTE measurement.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339094-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 775〈/p〉 〈p〉Author(s): Feng Hong, Haiming Cheng, Yan Song, Dan Li, Guixia Liu, Wensheng Yu, Jinxian Wang, Xiangting Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Non-rare-earth red phosphors as alternative to commercial (oxy) nitride phosphors have attracted considerable attention for energy-efficient warm white light-emitting diodes (WLEDs). An excellent narrow-band red emission K〈sub〉2〈/sub〉GeF〈sub〉6〈/sub〉:Mn〈sup〉4+〈/sup〉 product was successfully obtained through co-precipitation method. The crystal structure, morphology, composition and optical properties of K〈sub〉2〈/sub〉GeF〈sub〉6〈/sub〉:Mn〈sup〉4+〈/sup〉 samples were investigated in details 〈em〉via〈/em〉 X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive spectrometry (EDS) and photoluminescence spectra, respectively. Mn〈sup〉4+〈/sup〉 activated K〈sub〉2〈/sub〉GeF〈sub〉6〈/sub〉 red phosphor possesses two strong and wide absorption bands in the region of 300–500 nm, which can be applied to UV and blue LED chips and bright intense red light (635 nm) with high color purity. Simultaneously, mechanisms of concentration and temperature quenching were systematically elucidated. After a systematic investigation, the luminescence properties of K〈sub〉2〈/sub〉GeF〈sub〉6〈/sub〉:Mn〈sup〉4+〈/sup〉 have been optimized by changing synthetic conditions, such as the doping concentration, the concentration of HF, the potassium source, the amount of KF and the addition of surfactant. The red phosphor K〈sub〉2〈/sub〉GeF〈sub〉6〈/sub〉:Mn〈sup〉4+〈/sup〉 was packaged 〈em〉via〈/em〉 mixing commercial YAG:Ce yellow phosphor, an outstanding warm WLED with low CCT (3882 K), high CRI (Ra = 90.4) and high luminous efficacy (LE) of 125.84 lm/W has been obtained, implying that K〈sub〉2〈/sub〉GeF〈sub〉6〈/sub〉:Mn〈sup〉4+〈/sup〉 is the potential red phosphor for warm WLEDs.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818331839-fx1.jpg" width="329" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Guozhong Huang, Peipei Zhang, Zhiming Bai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel ZnO nanowire arrays (NAs)/graphene(G)/CdS/electrolyte heterojunction was successfully prepared via a simple three-step synthesis method when applied for photoelectrochemical type self-powered UV–visible photodetectors. Under zero bias, the responsivities of the self-powered UV–visible photodetectors on the basis of ZnO NAs/G/CdS/electrolyte heterojunctions are 27.3 mA/W and 4.3 mA/W for the UV and visible light, respectively, with fast rise and decay times (5 ms). Graphene improves the response of ZnO NAs to UV and visible light to a certain extent owing to its excellent charge-collecting ability and the acceleration of carrier separation and transference. After covering photosensitive CdS nanoparticles, the response to visible light is greatly increased because of the type II energy band structure of ZnO/CdS. It could be inferred from the evidence that the ZnO NAs/G/CdS/electrolyte heterojunction performs effectively in the aspect of self-powered UV–visible detection.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): W. Cui, J. Pan, D.J. Blackwood, Y. Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Many previous simulations of the plastic deformation in metallic glasses showed that shear banding is the dominant mode accompanied by Voronoi volume continuous generation and softening. In the present work, we report a contrary phenomenon where Voronoi volume recovery is dominant during plastic deformation in CuZr metallic glasses under tension. By creating a notched geometry, the deformation mode of notched samples transits from shear banding to necking due to the introduction of triaxial stress state. With the suppressing of shear banding, a notch strengthening and structure ordering phenomenon together with the recovery of Cu-centered full-icosahedra fraction are also observed. The present work enriches our understanding on the mechanical behavior and deformation mechanism of metallic glasses.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339124-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Ting Wang, Ke Han, Qi Tang, Binggang Zhang, Jicai Feng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electron beam welding of titanium to copper has been performed with different Cu-V filler metals. Microstructure, mechanical properties and fracture behavior were investigated. Compared with the welded joint without filler metal, the lower V content in Cu75V25 filler metal resulted in the formation of fine Ti-Cu compounds in the interface of TA15 side. Thus, the joint showed a lower tensile strength and fractured along the interfacial reactive layer. When V content is over 34 wt% in the filler metal, the interfacial microstructure near TA15 side formed cellular (Ti,V) solid solution to replace the Ti-Cu compounds, which improved the mechanical properties of the joint. As a result, the joint with Cu66V34 filler metal displayed the highest tensile strength (384 MPa), approaching 82% of that of the copper base metal (BM), and fractured in heat affected zone (HAZ) of copper side, due to the local softening by grains coarsening. In spite of the formed solid solution at the interface, the joint welded with Cu34V66 filler metal containing higher V content, produced amount of pores and unmelted V alloy, which resulted in the decrease of tensile strength down to 55% of that of the copper BM.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818338969-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): M. Bououdina, A.A. Dakhel, A. Jaafar, J.H. Dai, Y. Song〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉This research work aims to study the effect of co-doping by Al〈sup〉3+〈/sup〉 to increase the electronic charge carrier concentration inversely to Mg〈sup〉2+〈/sup〉. Zn〈sub〉0.97〈/sub〉Gd〈sub〉0.03〈/sub〉O, Zn〈sub〉0.95〈/sub〉Gd〈sub〉0.03〈/sub〉Mg〈sub〉0.02〈/sub〉O, and Zn〈sub〉0.95〈/sub〉Gd〈sub〉0.03〈/sub〉Al〈sub〉0.02〈/sub〉O nanopowders were synthesised by simultaneous thermal co-decomposition of a mixture of cadmium and metal complexes, followed by hydrogenation at 350 and 600 °C. This study aimed at establishing the preparation conditions including hydrogenation that were essential for the creation of room temperature ferromagnetic order starting from the paramagnetic Gd-doped ZnO by using structural and electronic consequences of codoping with ions of Al or Mg. X-ray diffraction analysis confirms total doping of (Gd, Mg and Al) impurities into ZnO host lattice as well as the absence of secondary compounds/oxides in the synthesised solid solutions. The reflectance has been found to be significantly affected upon co-doping and hydrogenation, while the energy band gap decreases slightly; i.e. Eg = 3.23–3.00 eV. Magnetic measurements reveal that all the as-synthesised doped ZnO powders gained paramagnetic behaviour defeating the diamagnetic characteristic of ZnO, due to the presence of Gd ions with an effective magnetic moment in the range 8.04–7.12 μ〈sub〉B〈/sub〉. The hydrogenation in the present work conditions did not change the paramagnetic behaviour except for ZnO:Gd:Al-H, showing a partial a magnetic order overlapping with paramagnetic component, resulting in a coercivity of 170.2 Oe, remanence of 0.550 memu/g, and saturation magnetization of 2.14 memu/g. Therefore, the conditions including hydrogenation that were necessary to create FM ordering were determined.〈/p〉 〈p〉First-principles calculations indicate that the Gd doped ZnO systems own large spin polarized effect due to the interaction between Gd-〈em〉f〈/em〉 and O-〈em〉p〈/em〉 electrons. The Mg and Al dopants can modulate the values of magnetic moments.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Jikang Sun, Wen Zhang, Shiying Wang, Yibin Ren, Qingyun Liu, Yanfang Sun, Lin Tang, Jinxue Guo, Xiao Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxygen evolution is the vital and limiting reaction in electrochemical water splitting because of the sluggish kinetics and searching efficient nonprecious metal electrocatalysts is a crucial demand to obtain sustainable and clean fuels. Transition metal borides have recently attracted increasing attention as promising catalysts for oxygen evolution reaction. Herein, ultrathin Ni-Co-B nanosheets have been vertically aligned on reduced graphene oxide as exceptionally efficient oxygen evolution reaction electrocatalyst for the first time. Controlled experiments indicate the critical role of reduced graphene oxide in guiding the formation of Ni-Co-B nanosheet. The catalyst affords a current density of 10 mA cm〈sup〉−2〈/sup〉 at low overpotential of 280 mV, which is better than most of metal boride catalysts reported to date. Stable current output is maintained at 20 mA cm〈sup〉−2〈/sup〉 for at least 60 h. We expect this work will arouse the interests on design of compositing two-dimensional metal borides with graphene, C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉, and metal dichalcogenides towards applications in energy storage and conversion, electrocatalysis, and sensing.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S092583881833977X-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Mikio Fukuhara, Tomoyuki Kuroda, Fumihiko Hasegawa, Yasuyuki Shirai, Toshiyuki Hashida, Kazuya Konno〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Blackish amorphous aluminium oxide film on AlY〈sub〉10〈/sub〉 amorphous alloy ribbons was prepared by anodic polarization process in H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 solutions, showing electric storage on uneven surfaces with a convexity of 18 nm in diameter. The longest discharging time was obtained by current ratio (I〈sub〉2〈/sub〉/I〈sub〉1〈/sub〉) of 0.4 at 16 V and 5 mass% H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉. The discharging time increases and decreases with increasing charging time and charging current, and then saturates after around 100 s and 1 μA, respectively. The resulting film shows a vertical line after Warburg region in a Nyquist diagram, rapid increases in the imaginary impedance, and a phase angle of −90° at 1 mHz in the Bode diagram, demonstrating evidence for use in an electric distributed constant circuit. The film indicates a switching effect for both positive (∼+8.6 eV) and negative (∼-11.2 eV) potentials.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Ping Zhou, Tianli Han, Cuiping Gu, Jinjin Li, Zihan Shen, Huigang Zhang, Junjie Niu, Jinhuai Liu, Jinyun Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High energy density Li-S battery has attracted broad attention; however the capacity retention is still non-ideal. The major challenge is to find a way to effectively prevent the shuttle effect of the lithium polysulfides during charging/discharging. Here, we present a novel wheel-confined composite consisting of MnO〈sub〉2〈/sub〉 nano-rod as wedge and SnO〈sub〉2〈/sub〉 sphere as the skeleton filled with sulfur, which was synthesized using a facile chemical method. The battery with the S@MnO〈sub〉2〈/sub〉@SnO〈sub〉2〈/sub〉 composite as cathode exhibits a capacity as high as 1323 mAh g〈sup〉−1〈/sup〉 at 0.1 C and a high capacity retention of only 0.03% decay per cycle over 500 cycles, which indicates a greatly reduced shuttle effect in Li-S batteries. The battery also shows good rate-performance and low-temperature properties. In addition, the I-V measurements and the first-principle calculations have demonstrated an enhanced electron transfer through the composite.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818338465-fx1.jpg" width="279" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Shiqiang Yue, Hua Zhang, Rijin Cheng, Anding Wang, Yaqiang Dong, Aina He, Hongwei Ni, Chain-Tsuan Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetic and thermal stabilities of Fe-based amorphous alloys with high saturation flux density (〈em〉B〈/em〉〈sub〉s〈/sub〉) are important for the application and understanding of the atomic interaction. Fe〈sub〉〈em〉x〈/em〉〈/sub〉(Si〈sub〉3〈/sub〉B〈sub〉13〈/sub〉)〈sub〉(100-x)/16〈/sub〉 (〈em〉x〈/em〉 = 86-71) eutectic amorphous alloys with superior manufacturability and Fe content limit were developed and the compositional effects were investigated. The alloys exhibit high 〈em〉B〈/em〉〈sub〉s〈/sub〉 of 1.53–1.68 T, low coercivity of 2.2–4.3 A/m, and high permeability of 8.8–12.8 × 10〈sup〉3〈/sup〉. With the increase of Fe content, it is found that the 〈em〉B〈/em〉〈sub〉s〈/sub〉 have an inflection point, the crystallization and Curie temperatures decrease drastically. The high Fe content alloys exhibit reduced thermal stabilities of magnetic properties, because the enhanced magnetic intercoupling effect is much lower than the weakened atomic bonding. For the alloys with 〈em〉x〈/em〉 = 71–74, the decline rate of 〈em〉B〈/em〉〈sub〉s〈/sub〉 is still lower than 10% at the extreme condition of 200 °C, while 〈em〉B〈/em〉〈sub〉s〈/sub〉 of the alloy with 〈em〉x〈/em〉 = 84 decreases more than 10% at 120 °C. The thermal stability of magnetic properties should be taken into consideration for the devices used in unique condition, especially for the high 〈em〉B〈/em〉〈sub〉s〈/sub〉 amorphous alloys.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Milivoj Plodinec, Ivana Grčić, Marc G. Willinger, Adnan Hammud, Xing Huang, Ivana Panžić, Andreja Gajović〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Novel forms of black TiO〈sub〉2〈/sub〉 nanotubes-based photocatalysts for water purification were prepared. Two features were combined: decoration of TiO〈sub〉2〈/sub〉 nanotube arrays with Ag nanoparticles (sample TiO〈sub〉2〈/sub〉-NT's@Ag) and further hydrogenation of this material (TiO〈sub〉2〈/sub〉-NT's@Ag-HA). Obtained photocatalysts show high efficiency for degradation of salicylic acid, a typical water-borne pollutant. The photocatalysts considerably exceed the photocatalytic properties of TiO〈sub〉2〈/sub〉 nanotubes and commercial TiO〈sub〉2〈/sub〉 P25 taken as a reference for modeling of the photocatalytic process. The comparison of photocatalytic activities between novel photocatalyst was based on a numerical approach supported by the complex kinetic model. This model allowed a separate study of different contributions on overall degradation rate. The contributions include: salicylic acid photolysis, photocatalysis in UVB, UVA and in the visible part of applied simulated solar irradiation. The superior photocatalytic performance of the photocatalyst TiO〈sub〉2〈/sub〉-NT's@Ag-HA, particularly under visible irradiation, was explained by the combined effect of a local surface plasmon resonance (LSPR) due to Ag nanoparticles and creation of additional energy levels in band-gap of TiO〈sub〉2〈/sub〉 due to Ti〈sup〉3+〈/sup〉 states at nanotube surfaces. The presence of Ag also positively influence charge separation of created electron-holes pairs. The synergy of several effects was quantified by a complex kinetic model through the factor of synergy, 〈em〉f〈/em〉〈sub〉Syn〈/sub〉. Stability testing indicated that the catalysts were stable for at least 20 h. The novel design of catalysts, attached on Ti foils, presents a solid base for the development of more efficient photocatalytic reactors for large-scale with a long-term activity.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339197-fx1.jpg" width="381" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Jian Wang, Yangyang Yin, Hongxia Jin, Jianwen Zhang, Yan Li, Chengwei Wang, Moyi Duan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The composite structures of tightly embedding the rare-earth oxide La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles into TiO〈sub〉2〈/sub〉 film are designed and have been successfully prepared by using the sol-gel and spin-coating method. Appearance of a large amount of nano-cracks on the La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉@TiO〈sub〉2〈/sub〉 composite film surface supplies a textured surface to study the effect of nanostructured surface on the electrowetting on dielectric (EWOD) performance. The characterizations of chemical composition and crystal phase structure indicate the La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles with polycrystalline nature have been grown and distribute uniformly in TiO〈sub〉2〈/sub〉 film. Valuably, plenty of intimate contact heterogeneous La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/TiO〈sub〉2〈/sub〉 interfaces are formed, and supply an ideal space for charge accumulation and electric energy storage. All data of EWOD response test show the applied superlow voltage can induce a large contact angle (CA) change, but the breakdown voltage is still high. The EWOD response does not agree with the well-known Young-Lippmann equation, especially obvious in low voltage range. Moreover, the optimal parameters of layer number of 8 and La〈sup〉3+〈/sup〉 doping concentration of 0.9% are obtained to enhance EWOD response for superlow applied voltage and the lower saturation CA. Detailed investigations and analysis reveal that the electric absorption has important roles on EWOD response under superlow applied voltage for the nanostructured surface. Furtherly, the space charge polarization theory is proposed to illustrate the enhancement of EWOD performance. When the voltage is applied, plenty of charges would be accumulated on the heterogeneous La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/TiO〈sub〉2〈/sub〉 interfaces and the space charge polarization is formed, this significantly heightens polarizability of the La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉@TiO〈sub〉2〈/sub〉 composite film, and further increases their effective dielectric constant and improves EWOD performance. But the electric absorption of water on the nanostructured surface causes the inconsistency of EWOD response with the tested and calculated capacitance. The present study shows a new insight to design and fabricate structured dielectric for the solution of EWOD difficulties.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Federico J. Pomiro, Juan P. Gaviría, Gastón G. Fouga, Leonardo D. Vega, Ana E. Bohé〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The reactions of Pr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and Pr〈sub〉6〈/sub〉O〈sub〉11〈/sub〉 with Cl〈sub〉2〈/sub〉(g) were studied thermodynamically and experimentally, and proposed in the systems Pr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Cl〈sub〉2〈/sub〉(g) and Pr〈sub〉6〈/sub〉O〈sub〉11〈/sub〉/Cl〈sub〉2〈/sub〉(g). A kinetic analysis was performed on Pr〈sub〉6〈/sub〉O〈sub〉11〈/sub〉 chlorination, which differs from with other light rare earth oxide chlorinations. The praseodymium oxychlorides obtained by full chlorination of Pr〈sub〉6〈/sub〉O〈sub〉11〈/sub〉 at 425 °C and 800 °C are different, being well characterized by X-ray diffraction, scanning electron microscopy, magnetic susceptibility measurements and X-ray photoelectron spectroscopy. The crystal structures of the oxychlorides were refined with the Rietveld method. The comparison between the theoretical magnetic moment of Pr〈sup〉3+〈/sup〉 and the estimated magnetic moment in the praseodymium oxychloride obtained at 425 °C revealed the presence of Pr〈sup〉3+〈/sup〉 and Pr〈sup〉4+〈/sup〉, whereas no significant difference was observed between the theoretical and the experimental values of Pr〈sup〉3+〈/sup〉 obtained for the praseodymium oxychloride prepared at 800 °C. These observations are consistent with the analyses in the X-ray photoelectron spectra for both oxychlorides. Finally, a general formula of PrO〈sub〉1+x〈/sub〉Cl is proposed for the oxychlorides synthesized at T 〈 800 °C.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Guang Chen, Jun Wang, Hongyuan Fan, Danqi Wang, Xiaoying Li, Hanshan Dong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Possibility of improving the resistance of AISI H13 steel to molten aluminum corrosion by liquid nitrocarburizing (LNC) was explored. The effects of the LNC parameters in terms of temperatures (703/723/743 K) and soaking time (4/8/12 h) on phase transformation, microstructure, and resistance to molten aluminum were fully studied. The surface phase compositions and the cross-sectional phase distribution of the LNC treated specimens were studied by implementable X-ray diffraction analysis. Microstructure, element distribution, microhardness, and the kinetics of the nitrocarburized case formation were fully researched. Immersion test of corrosion resistance to molten aluminum was carried out at 1023 K for 30min. It is observed that an oxide layer can be produced on the top of the nitrocarburized case during LNC treatment, which cannot be regularly produced by other nitriding methods. The nitrocarburized case consists of a compound layer, a diffusion layer, and a transition layer. The growth of the nitrocarburized case is proportional to the squared treatment time and follows the Arrhenius law for the treatment temperature. The activation energy is estimated to be 195.4 kJ mol〈sup〉−1〈/sup〉. While the nitrocarburized case provided limited resistance to molten aluminum, the oxide layer formed on the top of the nitrocarburized case conferred significantly improved molten aluminum corrosion resistance, especially a duplex oxide layer produced at 743 K.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Z. Mroczek, A. Morawski, T. Czujko, F. Karaboğa, M. Akdoğan, A.J. Zaleski, M. Małecka, T. Cetner, H. Yetiş, D. Gajda, I. Belenli〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this article, the significant impact of a lamellar (layered) structure and a high isostatic pressure on the normal state resistance (〈em〉R〈/em〉〈sub〉n〈/sub〉), critical temperature (〈em〉T〈/em〉〈sub〉c〈/sub〉), irreversible magnetic field (〈em〉B〈/em〉〈sub〉irr〈/sub〉), upper magnetic field (〈em〉B〈/em〉〈sub〉c2〈/sub〉) and critical current densities (〈em〉J〈/em〉〈sub〉c〈/sub〉) at 4.2 K and 20 K was presented. Our research showed that annealing at temperatures in the range of 630 °C–680 °C (above the melting point of Mg) at atmospheric pressure (0.1 MPa) did not create a lamellar (layered) structure. This led to low 〈em〉T〈/em〉〈sub〉c〈/sub〉, 〈em〉J〈/em〉〈sub〉c〈/sub〉 and 〈em〉B〈/em〉〈sub〉irr〈/sub〉 and high 〈em〉R〈/em〉〈sub〉n〈/sub〉. The analysis, made by using scanning electron microscopy (SEM), showed that the annealing temperature increased up to 700 °C under a pressure of 0.1 MPa, which created a lamellar structure. This led to significant growth of 〈em〉T〈/em〉〈sub〉c〈/sub〉, 〈em〉J〈/em〉〈sub〉c〈/sub〉 and 〈em〉B〈/em〉〈sub〉irr〈/sub〉 and a slight increase of 〈em〉R〈/em〉〈sub〉n〈/sub〉. Moreover, the measurements showed that annealing at temperatures from 630 °C to 700 °C did not change the 〈em〉B〈/em〉〈sub〉c2〈/sub〉 value. In comparison to pressureless heat treatment, annealing under the high isostatic pressure of 1.1 GPa obtained a lamellar structure with layers of lower thickness and higher density. This led to significant increases in 〈em〉J〈/em〉〈sub〉c〈/sub〉 and 〈em〉B〈/em〉〈sub〉irr〈/sub〉 and a visible reduction of 〈em〉R〈/em〉〈sub〉n〈/sub〉. SEM analysis showed that the increase of isostatic pressure up to 0.3 GPa created a lamellar structure with thicker layers and lower density. This microstructure led to lower 〈em〉J〈/em〉〈sub〉c〈/sub〉 and 〈em〉B〈/em〉〈sub〉irr〈/sub〉 and significantly higher 〈em〉R〈/em〉〈sub〉n〈/sub〉. On the other hand, the SEM analysis showed that annealing under 0.8 GPa did not cause the formation of a layered structure, and as a result, it led to significant reductions in 〈em〉B〈/em〉〈sub〉irr〈/sub〉 and 〈em〉J〈/em〉〈sub〉c〈/sub〉 (4.2 K and 20 K) and higher 〈em〉R〈/em〉〈sub〉n〈/sub〉. The increase of the isostatic pressure from 0.1 MPa to 1.1 GPa did not affect 〈em〉T〈/em〉〈sub〉c〈/sub〉 (〈em〉B〈/em〉 = 0 T) and 〈em〉B〈/em〉〈sub〉c2〈/sub〉. The results indicated that the layered structure obtained a high density of pinning centers, which were particularly effective at higher magnetic fields. 〈em〉J〈/em〉〈sub〉c〈/sub〉 of 100 A/mm〈sup〉2〈/sup〉 in 8 T at 4.2 K was obtained in 〈em〉in situ〈/em〉 undoped MgB〈sub〉2〈/sub〉 wires after annealing at 700 °C for 40 min under an isostatic pressure of 1.1 GPa.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339434-fx1.jpg" width="267" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Si-Ming Zeng, Xin-Gui Tang, Qiu-Xiang Liu, Yan-Ping Jiang, Ming-Ding Li, Wen-Hua Li, Zhen-Hua Tang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉BaCe〈sub〉x〈/sub〉Ti〈sub〉1−x〈/sub〉O〈sub〉3〈/sub〉 (BCT) ceramics at x = 0.025, 0.05, 0.075 and 0.1 were prepared by the traditional solid state reaction route and sintered at 1540 °C for 6 h. The microstructural, dielectric, electrocaloric, and pyroelectric performances of BCT were systematically explored. Hysteresis loops were measured under various temperatures, and the electrocaloric effect (ECE) was calculated for all samples. The results showed that BaCe〈sub〉0.075〈/sub〉T〈sub〉0.925〈/sub〉O〈sub〉3〈/sub〉 had the best ECE which exhibited a large adiabatic temperature change of 0.81 K, an isothermal entropy change of 0.82 JK〈sup〉−1〈/sup〉kg〈sup〉−1〈/sup〉 and an electrocaloric strength of ∼0.28 Km/MV. Further, the pyroelectric figure of merits (FOMs) were analyzed and the results indicated that BaCe〈sub〉0.1〈/sub〉T〈sub〉0.9〈/sub〉O〈sub〉3〈/sub〉 would be a better candidate for pyroelectric devices which exhibited high pyroelectric coefficient (p) of 7.82 × 10〈sup〉−4〈/sup〉〈em〉Cm〈/em〉〈sup〉−2〈/sup〉K〈sup〉−1〈/sup〉 and FOM of high detectivity (F〈sub〉d〈/sub〉) of 10.39 μPa〈sup〉−1/2〈/sup〉. These results in this work would facilitated the development of the electrocaloric and pyroelectric performance of Ce-doped BaTiO〈sub〉3〈/sub〉 ceramics.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Baishun Li, Kai Guan, Qiang Yang, Xiaodong Niu, Dongdong Zhang, Shuhui Lv, Fanzhi Meng, Yuanding Huang, Norbert Hort, Jian Meng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Microstructures and mechanical properties of a Mg−8Gd−3Yb−1.2Zn−0.5Zr (wt%) alloy have been investigated. The dominant intermetallic phases in the as-cast sample are Mg〈sub〉5〈/sub〉RE (RE = Gd,Yb) phase, 14H-type long-period stacking ordered (LPSO) phase, and Mg〈sub〉2〈/sub〉Zn〈sub〉2〈/sub〉RE (W) phase and ordered Mg〈sub〉12〈/sub〉RE phase. Furthermore, the ordered Mg〈sub〉12〈/sub〉RE phase generally coexists with the W phase following an orientation relationship as [0〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉1]〈sub〉w〈/sub〉//[〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mn〉2〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉30]〈sub〉Mg12RE〈/sub〉, and (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉11)〈sub〉w〈/sub〉//(001)〈sub〉Mg12RE〈/sub〉. After extrusion, the microstructure is consisted of un-recrystallized regions along with a small part of fine dynamically recrystallized (DRXed) regions. Simultaneously, the coarse Mg〈sub〉5〈/sub〉RE, W and Mg〈sub〉12〈/sub〉RE particles were disintegrated and mainly distribute at extrusion stringers while the fine LPSO plates mainly distribute in un-recrystallized regions. Moreover, amounts of nanoscale Mg〈sub〉5〈/sub〉RE particles were dynamically precipitated in DXRed regions. Then, the as-extruded Mg−8Gd−3Yb−1.2Zn−0.5Zr alloy exhibits clearly higher strength than the classic rare-earth-containing magnesium alloys with comparative or even much higher rare earth content at both room temperature and high temperatures. The dominant strengthening mechanism was finally revealed as precipitation/dispersion strengthening.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): An-Nan Chen, Meng Li, Jia-Min Wu, Li-Jin Cheng, Rong-Zhen Liu, Yu-Sheng Shi, Chen-Hui Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Highly porous mullite ceramics with bimodal pore structures were fabricated by selective laser sintering (SLS), in which the closed pores were provided by core-shell structure of fly ash hollow spheres (FAHSs) and the open pore channels were created by spherical polyamides (PA12). With increasing sintering temperature, the total porosity of mullite ceramics decreased, in which the average closed pore size reduced and the average open pore size distribution kept constant, however, the compressive strength of ceramic foams increased. This strength enhancement was mainly attributed to the reinforced sintering necks between FAHSs when sintered below 1350 °C, which resulted from the liquid phase diffusion of K, Ca and Ti, while the densification and thickening of sphere shell walls played a key role when above 1350 °C. Our findings illustrate that understanding pore structure characteristics and strength enhancement mechanism changes will be helpful for designing highly porous mullite ceramics with high mechanical performance.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818340362-fx1.jpg" width="281" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Ting Zhang, Lehua Qi, Jiawei Fu, Jiming Zhou, Xujiang Chao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present study, carbon fibers grafted with SiC nanowires (C〈sub〉f〈/sub〉-SiCNWs) reinforced AZ91D composite (C〈sub〉f〈/sub〉-SiCNWs/AZ91D) was prepared by liquid-solid extrusion following vacuum infiltration (LSEVI) process. The effect of SiC nanowires (SiCNWs) on the interfacial microstructure, tensile properties and fracture behavior of the C〈sub〉f〈/sub〉-SiCNWs/AZ91D composite were investigated. First, the microstructure and fracture surface of the composite were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results showed that after introducing SiCNWs, the antioxidation of carbon fiber could be reasonably improved, which provided a better interface of the C〈sub〉f〈/sub〉-SiCNWs/AZ91D composite by preventing the detrimental interfacial reaction product of Al〈sub〉4〈/sub〉C〈sub〉3〈/sub〉. Then, the average ultimate tensile strength of SiCNWs-C〈sub〉f〈/sub〉/AZ91D composite was compared with that of C〈sub〉f〈/sub〉/AZ91D composite. It was found that after grafting SiCNWs on the surface of carbon fibers, the strength increased from 269.7 MPa to 358.8 MPa, corresponding to an improvement of 33%. This increase was attributed to the improved interface that took advantages of the superior mechanical properties of SiCNWs.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Viney Dixit, Jacques Huot〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉In this paper we report the effect of Ti-proportion and addition of Zr-Ni on the crystal structure, morphology and hydrogen storage kinetics of Ti-V-Cr alloy. For this study, five alloys of compositions Ti〈sub〉x〈/sub〉V〈sub〉70-x〈/sub〉Cr〈sub〉30〈/sub〉 (x = 10, 20, 30, 40, 50) added with 4 wt% of 7Zr+10Ni were synthesized. Scanning electron microscopy revealed that all alloys were multiphase. X-ray powder diffraction confirmed that all the as-cast alloys have the body-centred cubic (bcc) phase as the main phase. The same amount of (7Zr+10Ni) was added in all of the alloys, but each alloy has shown a different elemental concentration in their secondary phases. For alloys x = 10 and 20, a Zr rich secondary phase was formed but for alloys x = 30, 40 and 50, the secondary phase has relatively high concentration of all elements.〈/p〉 〈p〉Upon hydrogenation, the bcc phase transformed into a face-centred cubic (fcc) phase. For x = 20, 30 and 40 a body-centred tetragonal (bct) phase was also observed along with fcc phase. Hydrogenation kinetics of all of these alloys was measured and it was found that absorption capacity increased with Ti-content. The maximum absorption capacity of 3.6 wt% was achieved for x = 50.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339574-fx1.jpg" width="256" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: 5 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Journal of Alloys and Compounds, Volume 776〈/p〉 〈p〉Author(s): Yu-Hua Wen, Li-Hong Zhang, Jin-Bo Wang, Rao Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pt〈sub〉3〈/sub〉Co nanoparticles are promising catalyst candidates for fuel-cell applications because their catalytic performances are superior to pure Pt nanoparticles. Fundamental insights into the thermostability of Pt〈sub〉3〈/sub〉Co nanoparticles are critical for their syntheses, post-treatments, and ultimate applications. In this article, the thermal stability of Pt〈sub〉3〈/sub〉Co nanoparticles has been investigated by molecular dynamics simulations. Two types of structures, chemically disordered alloy and ordered intermetallic compound, are considered. Besides, two-atomic-layered Pt and Co have been introduced to coat the Pt〈sub〉3〈/sub〉Co nanoparticles to form Pt〈sub〉3〈/sub〉Co-Pt and Pt〈sub〉3〈/sub〉Co-Co core-shell nanoparticles. The simulated results reveal that the ordered intermetallic Pt〈sub〉3〈/sub〉Co nanoparticles exhibit better thermal stability than the disordered alloy ones. Pt coating is greatly superior to Co coating for improving both structural and thermal stability of Pt〈sub〉3〈/sub〉Co nanoparticles. For Pt〈sub〉3〈/sub〉Co and Pt coated Pt〈sub〉3〈/sub〉Co nanoparticles, the overall melting simultaneously happens in both Pt and Co. However, Co-coated surface induces the two-stage melting of Pt〈sub〉3〈/sub〉Co nanoparticles at large sizes; it markedly decreases the thermal stability of the nanoparticles at small sizes, resulting in the melting point even lower than pure Co ones. The remarkably lowered melting temperature is associated with the order-to-disorder transformation in the Co-coated shell and the appreciable change of particle shape before surface premelting.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0925838818339495-fx1.jpg" width="257" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 31 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Catalysis Today〈/p〉 〈p〉Author(s): Haibiao Yu, Xinping Wang, Ye Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For the Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉/CaCO〈sub〉3〈/sub〉 catalysts used for N〈sub〉2〈/sub〉O decomposition, the activity of the catalyst prepared by stepwise precipitation is much superior to the catalysts prepared by impregnation or coprecipitation in the same composition. HRTEM observation and EDX analysis indicate that the stepwise precipitation leads to cobalt existing as little Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 crystallites tightly bound to the CaCO〈sub〉3〈/sub〉 particles. The special structure made the Co〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 ideal accessibility and better interaction with the support in the catalyst, and the CaCo〈sub〉2.5〈/sub〉(SP) catalyst with this structure is much more active than the CaCo〈sub〉2.5〈/sub〉 catalyst reported in literature prepared in traditional method. At 300 °C, N〈sub〉2〈/sub〉O in the feed gas 2000 ppmv N〈sub〉2〈/sub〉O/Ar was completely converted over the CaCo〈sub〉2.5〈/sub〉(SP) at 20,000 h〈sup〉−1〈/sup〉. Moreover, the CaCo〈sub〉2.5〈/sub〉(SP) catalyst exhibited better resistance to sintering at 800 °C and quite high activity under the presence of 5 vol% O〈sub〉2〈/sub〉 and 2 vol% H〈sub〉2〈/sub〉O at 350 °C as well.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0920586118311611-ga1.jpg" width="361" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Shuai Sun, Lei Wang, Chengyang Wang, Yang Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Coal tar pitch with a softening point (SP) of 78 °C is mixed with divinylbenzene (DVB) and then spheroidized by suspension method in dimethyl silicone oil for 1 h. During the spheroidization process, the mixtures of pitch and DVB are copolymerized due to vinyl in DVB. After vacuum-assisted heat treatment, the copolymer spheres can be stabilized completely and then carbonized directly at high temperature under Ar atmosphere without melting and deformation. After activation using steam at 850 °C for 1.5 h, spherical activated carbon (SAC) with smooth surface and specific surface area S〈sub〉BET〈/sub〉 = 520 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉 can be prepared. Further studies show that mesopore volume of the SAC is 0.29 cm〈sup〉3〈/sup〉 g〈sup〉−1〈/sup〉, which accounts for 72.5% of the total pore volume. The good spherical morphology, smooth surface and rich pores (micropores and mesopores) can be attributed to appropriate copolymerization and vacuum-assisted treatment.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 16 May 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum〈/p〉 〈p〉Author(s): Yuki Murayama, Kazuma Ueno, Yuya Oshio, Hideyuki Horisawa, Ikkoh Funaki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Magnetic sail (MagSail) is a space propulsion system utilizing an interaction between the solar wind particles and the artificial magnetic field generated by the coil on the spacecraft. The thrust is proportional to the magnetospheric size. In order to improve an efficiency of capturing the solar wind, a multi-coil magnetic sail, using several coils, is proposed. In this research, to evaluate the magnetospheric size of multi-coil magnetic sail, multi-coil magnetic sail consisted of three-small coils was developed and the magnetic field strength was characterized by the magnetic field probes. As a result, a 330 mm-magnetosphere was found in the normalized magnetic field distribution. In space, the ion Larmor radius at the magnetospheric boundary 〈em〉r〈/em〉〈sub〉〈em〉Li〈/em〉〈/sub〉 is about 72 km at 1 AU from the sun, and a magnetospheric size in space 〈em〉L〈/em〉〈sub〉space〈/sub〉 = 1.6 km is obtained by substitution 〈em〉r〈/em〉〈sub〉〈em〉Li〈/em〉〈/sub〉 = 72 km for the non-dimensional parameter 〈em〉r〈/em〉〈sub〉Li〈/sub〉/〈em〉L〈/em〉 = 4.5, then, MagSail produce 82 mN thrust.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): M. Jaroš, J. Musil, R. Čerstvý, S. Haviar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The article reports on the effect of the energy ℰ delivered into the growing film on its macrostress, microstructure, mechanical properties and resistance to cracking of Ti(Al,V)N films. The Ti(Al,V)N films were deposited on Si(111) and Mo substrates by magnetron sputtering in a mixture Ar + N〈sub〉2〈/sub〉 gases using a dual magnetron with closed magnetic field and equipped with TiAlV (6 at.% Al, 4 at.% V) alloy targets. It is shown that the compressive macrostress σ in sputtered films can be reduced either by the pulsed bipolar bias voltage U〈sub〉sp〈/sub〉 with alternating negative and positive pulses or the electron and ion bombardment during overshoots in the pulsed magnetron sputtering. All sputtered films with high ratio H/E〈sup〉∗〈/sup〉 ≥ 0.1, compressive macrostress (σ 〈 0), and non-columnar microstructure exhibit an enhanced resistance to cracking; here H is the hardness and E〈sup〉∗〈/sup〉 is the effective Young's modulus. The high compressive macrostress in the film is not the necessary condition for the formation of the films with an enhanced resistance to cracking.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 159〈/p〉 〈p〉Author(s): S. Balamurugan, A.R. Balu, J. Srivind, K. Usharani, V. Narasimman, M. Suganya, V.S. Nagarethinam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present work aims to synthesize CdO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanocomposite and to study its visible light activated photocatalytic performance against metanil yellow dye. Precipitation method was employed to synthesize pure CdO, Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and CdO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles. Diffraction peaks related to cubic CdO and monoclinic θ-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 were observed in the XRD pattern of the composite. XPS spectrum confirmed the presence of Cd, Al and O in the composite. Peaks related to Cd〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O and O〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉O bonds were observed from the FTIR spectrum of the composite. Photocatalytic activity confirmed that the CdO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanocomposite exhibits a maximum degradation efficiency of 82.09% against MY dye which was found to be better than pure CdO and Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles due to the synergistic effect, high surface area and the formation of p-n junction at the interface of CdO and Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. The CdO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 composite catalyst synthesized via precipitation method seems to be more stable and definitely it will be a potential candidate in photocatalysis related field.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): A. Kozlovskiy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The paper presents the results of studying the effect of irradiation of Fe〈sup〉7+〈/sup〉 ions with an energy of 1.5 MeV/nucleon on structural properties of AlN ceramics at an irradiation temperature of 300, 500, 700 and 1000 K. The choice of ion type and irradiation conditions was made by studying the processes of defect formation as a result of particles effect with energies close to fission fragments of nuclear fuel (≤90–100 MeV) and temperatures 0.1–0.3 T〈sub〉melt〈/sub〉, typical for annealing defects. From the data obtained by the XRD, SEM, EDX methods, it is established that an increase in irradiation temperature above 500 K leads to a reduction in distortions and deformation of the crystal lattice under irradiation. It was found that with an increase in the irradiation dose, amorphous-like grains with a high oxygen content are formed in the structure, which are characteristic for the impurity phase of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, the content of which in the ceramic structure does not exceed 5%. In this case, an increase in the irradiation temperature leads to a decrease in impurity phase concentration in the structure. It has been established that for samples irradiated at high temperatures 700–1000 K, the decrease in strength properties is less than for samples irradiated at a temperature of 300 and 500 K. Such a difference can be explained by partial annealing and annihilation of defects as a result of elevated temperatures. The decrease in thermal conductivity coefficient in irradiated samples is due to an increase in defects concentration in structure, as well as a decrease in their mobility.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): R.Z. Xu, H. Li, Y.X. Hou, Z.C. Wei, F.S. Li, S.L. Cui, X.H. Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The characteristics of vacuum electron beam welding (VEBW) of AZ31 Mg alloy (2.4 mm) to Q235 steel (2.0 mm) were investigated. The results showed that AZ31 and noncoated Q235 could not be joined together after VEBW. With an addition of Al-Zn coating, the lap joint of AZ31 and Q235 was obtained successfully. Firstly, the high amount of Al in the Al–Zn coating decreased the excessive vaporization of Zn. Secondly, the reasonable vaporization of Zn element and diffusion into the AZ31 of Al element in the coating improved the wettability of Mg/steel faying surface during the EBW process in vacuum conditions. Thirdly, the pre-existing Al–Fe intermetallic compound (IMC) was molten and kept at the Mg-steel interface, preventing a direct contact between molten Mg and steel during EBW. Subsequently, it formed an Al〈sub〉5〈/sub〉Fe〈sub〉2〈/sub〉 IMC layer, realizing the metallurgical bonding of AZ31 to Q235. The hardness testing indicated that the Al-Fe interface zone exhibited a peak in the hardness values. The average load of the AZ31/Al-Zn-coated Q235 joint with a width of 10 mm could reach 2.2 kN and the lap joint fractured at the faying surface between Al〈sub〉5〈/sub〉Fe〈sub〉2〈/sub〉 IMC layer and AZ31 substrate after tensile-shear testing.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 23 August 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum〈/p〉 〈p〉Author(s): R. Sitek〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The article discusses the effect of high temperature aluminizing processes on microstructure and corrosion resistance in 0.1 M Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 solution at room temperature of the IN 740H nickel superalloy. The aluminizing processes were carried out by chemical vapor deposition (CVD): (a) in AlCl〈sub〉3〈/sub〉 vapors, (b) in a mixture of AlCl〈sub〉3〈/sub〉+ZrCl〈sub〉3〈/sub〉 vapors under a hydrogen atmosphere as carrier gas under the same conditions (process temperature −1040 °C, time-7h under reduced pressure of 150 hPa). Observations of the surface of the produced layers showed that the additional modification of the aluminizing process with zirconium affects the morphology of the layers formed as compared to the unmodified aluminizing process. It was also found that the prepared aluminide layers unmodified and modified additionally with zirconium improve corrosion resistance of the Inconel 740H nickel superalloy. On the basis of the conducted tests, it was also found that after high-temperature aluminizing processes in the IN 740H substrate precipitates are formed at the grain boundaries containing carbide forming elements such as: Cr, Ti, Nb, which may form secondary carbides, e.g. M〈sub〉6〈/sub〉C, M〈sub〉7〈/sub〉C〈sub〉3〈/sub〉.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 159〈/p〉 〈p〉Author(s): Oleg Sazhin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of surface roughness on free molecular gas flow in 3-D rectangular channel is studied by the test particle Monte Carlo method. It is shown that the so-called “superdiffuse” scattering observed in a number of flow experiments is a result of disregarding the surface roughness effect. Its consideration leads to a satisfactory agreement between the computed and experimental data.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Bharath Bandi, Soumitra Kumar Dinda, Jyotirmaya Kar, Gour Gopal Roy, Prakash Srirangam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Zircaloy-4 to Zircaloy-4 (Zr-4) similar butt joints were prepared using Electron Beam Welding (EBW) technique under different weld conditions such as with beam oscillation, without beam oscillation and at different welding speeds. Three-dimensional (3D) visualisation of porosity in weld joints was carried out using X-ray computed tomography (XCT) technique. Quantification of porosity such as the average size, number and shape of the pores were evaluated and compared among weld joints produced under different conditions. XCT results show that the porosity of the welds increased substantially with the increase in the weld speed. More interestingly, the results also show that there is a significant decrease in porosity of the joint produced with beam oscillation condition. An increase in weld speed from 700 mm/min to 1000 mm/min resulted in a significant increase in pore density (from 16 to 313 per mm3) and it was observed that the average size of the macro pores increased from 96.4 μm to 121.5 μm. The joints prepared with beam oscillation produced least number of pores with minimum percentage of macro pores and maximum percentage of spherical pores in it. Raman spectroscopy results confirmed the presence of hydrogen gas in pores of all the weld joints.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Yongdong Wang, Jixiao Wang, Haiting Hu, Junsheng Meng, Xia Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉By using Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles, instead of part or all of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, acting as filler, Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-modified aluminide coatings were produced on 309 stainless steel using a conventional pack-cementation method at 700 °C for 6 h. Effect of Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 content in the pack mixtures on the cyclic-oxidation resistance of different aluminide coatings was comparably investigated. The results show that the phase of aluminide coatings was Fe〈sub〉24〈/sub〉Al〈sub〉76.8〈/sub〉. With the increase of Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 content in the pack mixtures, the thickness of aluminide coatings decreased but the cyclic-oxidation resistance at 900 °C in air increased, because of prevention of cavities at the alumina scale/coating interface, and because of mitigation of degradation of the aluminide coating due to decreased outward diffusion and inward interdiffusion between the aluminide and the 309 stainless base. The reasons for the results are discussed.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Yu Liu, Zhao Zhang, Guangqiang Li, Yang Wu, Deming Xu, Baokuan Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, five types of CaF〈sub〉2〈/sub〉〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉CaO〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 slags with varying CaO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 mass ratio and CaF〈sub〉2〈/sub〉 content were selected for investigating the vaporization behavior of slag bearing high CaF〈sub〉2〈/sub〉 content by thermo gravimetry and ion and molecule coexistence theory. The results show that the volatile product of slag is the AlF〈sub〉3〈/sub〉. The vaporization rate is affected by the vapor pressure of AlF〈sub〉3〈/sub〉, mole number of complex molecules and the viscosity of slag. For all slags, the vaporization rate of slag bearing approximately 70 wt% CaF〈sub〉2〈/sub〉 and 30 wt% Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 is the fastest due to the ultra-high vapor pressure of AlF〈sub〉3〈/sub〉. In the test of slags containing 70 wt% CaF〈sub〉2〈/sub〉, vaporization rate firstly decreases, then increases with CaO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 mass ratio increasing from 0.05 to 1.10 and 2.00. In the case of slags containing same CaO/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 mass ratio, vaporization rate firstly increases, then decreases with CaF〈sub〉2〈/sub〉 content decreasing from 68.9 wt% to 48.1 wt% and 28.7 wt%. Slag T5 bearing approximately 30 wt% CaF〈sub〉2〈/sub〉, 33.9 wt% CaO and 36.1 wt % Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 has lower electrical conductivity, slower vaporization rate and larger sulfide capacity, which will be economical, environmentally friendly and suitable for vacuum electroslag remelting.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 28 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum〈/p〉 〈p〉Author(s): Catalina Ciobotaru, Ion Gruia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The monochromatization-effect of visible light (the M-effect) emitted from electronegative-electropositive gas mixture plasma consists in dramatic reduction the spectrum of electropositive gas to one or a few very intense spectral lines in relation to the other lines. The main generation mechanism of this process is the polar-resonant reaction of three-body. The article presents the influence of the reaction energy defect size on the degree of polarization of quasi-monochrome light emitted by a plasma discharge of a very low radio frequency, at a total pressure of gaseous mixture of about 10〈sup〉3〈/sup〉 Pa. This requirement is correlated with the existence of two other criteria, important for the mentioned effect, namely the emission probability of spectral line and the number of electronegative gas metastable atoms. Recorded data are comparatively analyzed for two situations de facto, with and without application of a magnetic field, leading us to the conclusion that the existence of a magnetic field in plasma increases the degree of polarization of the emitted monochrome light.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Y. Wang, Y.T. Zhao, Z.W. Yang, D.P. Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Vacuum brazing was applied to join Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ceramic and pure Nb with two active Ag-based fillers, Ag-Cu-Ti and Ag-Cu-Ti + Mo. The influences of the brazing parameter and the content of Mo particles on the microstructure and mechanical properties of the brazed joint were studied. The typical interfacial structure of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Nb joint brazed with Ag-Cu-Ti filler metal at 900 °C for 10 min was Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Ti〈sub〉3〈/sub〉(Cu,Al)〈sub〉3〈/sub〉O/TiCu+Ti〈sub〉2〈/sub〉Cu〈sub〉3〈/sub〉+TiCu〈sub〉4〈/sub〉+Ag(s,s)+Cu(s,s)/Nb. In the joints brazed with Mo particle-modified composite filler, the large blocky Ti-Cu compounds disappeared, and a large number of fine phases formed in the brazing seam. The dissolved Mo played a better role in refining the microstructure compared with residual Mo particles. In addition, the finite element method (FEM) calculated results showed that the residual stress peak value of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Nb brazed joint decreased from 296 MPa to 253 MPa when 8 wt. % Mo particles were added in the composite filler. The shear strength of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Nb brazed joints could reach up to 203 MPa at 900 °C for 10 min. The joining properties of the Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Nb brazed joint were primarily dependent on the dispersion degree of fine Ti-Cu compounds and the thickness of Ti〈sub〉3〈/sub〉(Cu,Al)〈sub〉3〈/sub〉O reaction layer.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Biren Patel, Ranjan K. Pati, Indrajit Mukhopadhyay, Abhijit Ray〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cu〈sub〉2〈/sub〉SnS〈sub〉3〈/sub〉 thin films have been deposited by using non-vacuum spray pyrolysis technique on soda lime glass substrates from single aqueous solution containing all the constituents. The effect of post deposition annealing of the Cu〈sub〉2〈/sub〉SnS〈sub〉3〈/sub〉 thin films on the composition, structural, optical and electrical properties has been studied. The XRD study reveals that vacuum annealing of the thin film gives rise to the evolution of Cu〈sub〉x〈/sub〉S〈sub〉y〈/sub〉 secondary phases by the loss of elemental tin, while the annealing held at sulphur atmosphere increases the crystallinity of the film without giving rise to any secondary phases. The Cu〈sub〉2〈/sub〉SnS〈sub〉3〈/sub〉 phase with preferred orientation along the (112) crystal direction grew to greater extent upon sulphur annealing associated with an improvement in the optical band gap. From the Raman analysis it was observed that as-deposited films are dominated by the presence of tetragonal crystal symmetry of the Cu〈sub〉2〈/sub〉SnS〈sub〉3〈/sub〉 phase. Upon vacuum annealing the peak appearing at 474 cm〈sup〉−1〈/sup〉 grows to greater extent which corresponds to CuS phase, and is in good agreement with the XRD spectra. Eventually its sulphur annealing gives the pure phase of Cu〈sub〉2〈/sub〉SnS〈sub〉3〈/sub〉 with dominating tetragonal crystal structure.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Andrey V. Kaziev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The properties of cathode sheath in a non-sputtering magnetron discharge are discussed involving the theoretical assumptions based on the classical glow discharge description, and magnetron specific effects. It is shown that in a wide range of experimental conditions (gas pressure 〈em〉p〈/em〉 from 1 to 100 Pa, discharge current 〈em〉I〈/em〉〈sub〉d〈/sub〉 from 10 to 1500 A), the trends for principal plasma parameters (electron density 〈em〉n〈/em〉 and temperature 〈em〉T〈/em〉〈sub〉e〈/sub〉) remain the same. Nevertheless, there is crucial difference in dominant supply of electrons between low pressure and elevated pressure non-sputtering magnetron regimes. Both secondary electron emission at low pressures and thermal ionization at high pressures result in sufficiently high electron source for sustaining dense non-sputtering magnetron plasmas at characteristically low voltage 〈em〉V〈/em〉〈sub〉d〈/sub〉 ∼ 80–120 V.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 159〈/p〉 〈p〉Author(s): Tuo Ye, Yuanzhi Wu, Anmin Liu, Congchang Xu, Luoxing Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The dynamic impact tests were performed on 6063 alloy with different initial aging conditions of under-aged (UA), peak-aged (PA) and over-aged (OA) at different strain rates ranging from 1 × 10〈sup〉3〈/sup〉 to 5 × 10〈sup〉3〈/sup〉 s〈sup〉−1〈/sup〉 by split Hopkinson pressure bar. The results show that dynamic deformation behavior is affected by initial aging condition, as well as strain rate. The PA alloy exhibits the highest flow stress and strain rate sensitivity (SRS), while the UA alloy displays the lowest flow stress and SRS. The dislocation and precipitate evolution were analyzed by TEM observations. During high strain rate deformation, the density of the dislocation increases with strain rate, the GP zones in the UA alloy are almost dissolved into the matrix, the number density of the 〈em〉β′′〈/em〉 precipitates in the PA alloy decreases with increasing strain rate due to the dynamic dissolution. The impact deformation results in a great energy differences between precipitates and matrix, precipitates dissolution occurs in order to balance the disrupted thermodynamic equilibrium. The dynamic evolution of the precipitates has a great effect on the mechanical property of the impacted 6063 alloy, it is necessary to consider the microstructure evolution in material selection and structure design.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 159〈/p〉 〈p〉Author(s): Jie Hu, Liang Zhang, Benqian Lu, Xueqian Wang, Hao Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new type of photocatalyst by the dispersion of LaMnO〈sub〉3〈/sub〉 nanoparticles on N doped porous biocarbon using a simple sol-gel method without adding any nitrogen source (such as NH〈sub〉3〈/sub〉, NH4OH, N〈sub〉2〈/sub〉H〈sub〉4〈/sub〉). Biochar is obtained from soybean dregs through two methods of hydrolysis and pyrolysis. The results show that the biocar obtained by two-step pyrolysis method is a better choice. The samples are characterized by field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence analysis, Brunauer-Emmett-Teller surface area analysis (BET) and UV-vis diffuse spectroscopy. It clearly demonstrates that composite exhibit an excellent photocatalytic activity in the degradation of Direct Green BE under UV-vis light because of its larger specific surface area, more active sites, improved charge separation efficiency and enhanced visible harvest ability. Furthermore, three typical N-bonding configurations in porous carbon is efficient for the enhanced photocatalytic activity, the h〈sup〉+〈/sup〉 and •O〈sub〉2〈/sub〉〈sup〉−〈/sup〉 play main roles in the photocatalytic system.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉The mechanism that occurs in the LaMnO〈sub〉3〈/sub〉/N doped porous carbon during photocatalytic process is shown in the figure. N substitution at “regular” C sites and can be present of three typical N-bonding configurations such as pyridinic, pyrrolic or graphitic nitrogen. The graphitic N can act as the electron-transfer mediator for the photogenerated electrons. Moreover, the pyridinic N and pyrrolic N at the edges or defects can function as the activation region for the oxygen reduction.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0042207X18315616-fx1.jpg" width="270" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 14 June 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum〈/p〉 〈p〉Author(s): Ai Momozawa, Rainer Telle〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study investigates thermal expansion and thermal vibration behavior of borides using HT-XRD. In the previous research, it has been known that the vibrational behavior directly expresses the behavior of materials at high temperatures. In this work, the high temperature X-ray diffraction (HT-XRD) measurements of TiB〈sub〉2〈/sub〉, W〈sub〉2〈/sub〉B〈sub〉4〈/sub〉, and CrB〈sub〉2〈/sub〉 were conducted at the high temperature ranges; up to 1500 K. From the generated results, the study calculates thermal expansion coefficients, which coincides the previous research. Rather, the study calculates the mean square displacements of borides for evaluating the thermal vibration behaviors at elevated temperatures, demonstrating that: (1) the application of a formula into HT-XRD data could determine Debye-Waller factors of these borides; (2) a term of “agglomeration” could contribute to defining the mean square displacement 〈em〉u〈/em〉〈sup〉2〈/sup〉; (3) both the Debye-Waller factor and the thermal expansion may function to design new boride-based materials at the high temperature; and (4) CrB〈sub〉2〈/sub〉 has a quick increase in mean square displacement and is remarkably large value at elevated temperatures.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Shaan Ameer, Kajal Jindal, Savita Sharma, Pradip K. Jha, Monika Tomar, Vinay Gupta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, the linear optical response of Cr doped BiFeO〈sub〉3〈/sub〉 (BFCO) using first principles calculations based on the density functional theory (DFT) is reported. The electronic and magnetic properties of BFCO are studied. Cr doping is found to result in an increase in magnetization in BFO. To corroborate the theoretical understanding in BFCO, Cr doped BFO thin film is also deposited via a multistep spin coating technique. The structural and optical characterization of the thin film are performed and the obtained results are compared with the theory.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 160〈/p〉 〈p〉Author(s): Guoming Zheng, Xiaonan Mao, Lei Li, Rui Dang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Microstructures and textures determine the mechanical properties of metal materials. In this work, a Ti6242S bar with ϕ260*129 mm scale was selected to study variation of microstructures and textures from edge to center by Optical Microscope and X-Ray Diffraction. Owing to the less plane stress, fast cooling rate and complex flow stress, grains size are quietly fine and macrotextures are close to nearly random in edge, which lead to the most excellent and homogeneous mechanical properties. By comparing feature of microstructure in R/2 and center position, larger volume fraction of α〈sub〉s〈/sub〉 colonies formed in center. Meanwhile, the main texture components were (11〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mn〉2〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉0) [1〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si4.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉00] and (11〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈mrow〉〈mover accent="true"〉〈mn〉2〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈/math〉0)[0001] in R/2, but symmetrical cubic texture with very high intensity come into being in center. More and larger α〈sub〉s〈/sub〉 colonies combine high-density texture jointly cause tensile strength and yield strength drop dramatically in center. Young's modulus is mainly influenced by textures, due to different texture in different location, edge was the largest, following by the center and R/2. The spheroidization of α〈sub〉p〈/sub〉 laths was completed in edge by strain-induced but dynamic recrystallization in R/2 and center by analyzing grain boundary feature and misorientation of EBSD data.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉In this work, three specimens were selected and labeled by S1, S2 and S3 which corresponding (a), (b) and (c) in images. The relationship among microstructure, macrotextures and mechanical properties can be concluded that (1) in side, both α〈sub〉p〈/sub〉 and α〈sub〉s〈/sub〉 grains are fine and macrotextures are close to random texture, which lead to the highest and homogeneous mechanical properties; (2) in R/2, most of grains are equixaial α〈sub〉p〈/sub〉 and (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈mn〉11〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉2〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉0〈/mn〉〈/mrow〉〈/math〉) [〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.gif" overflow="scroll"〉〈mrow〉〈mn〉1〈/mn〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo〉¯〈/mo〉〈/mover〉〈/mrow〉〈mn〉00〈/mn〉〈/mrow〉〈/math〉] texture was come into being, so a good match between strength and ductility are gained; (3) in center, the width of α〈sub〉s〈/sub〉 grains is about two times of R/2 and with more larger α〈sub〉s〈/sub〉 colonies, the size of α〈sub〉p〈/sub〉 is similar to R/2 but smaller volume fraction. In addition, symmetrical cubic texture with maximum intensity of 7.9 times random is formed, which combine to led to tensile and yield strength drop quickly.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0042207X18316567-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: Available online 1 August 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum〈/p〉 〈p〉Author(s): Yung-An Chan, Georg Herdrich〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Characterization of IEC tight jet mode is achieved through Faraday probe measurements. Preliminary results indicate that the tight jet is a highly energetic electron beam with scattering of secondary ions and electrons, which result from electron beam impact ionization. A novel analytical model is proposed to evaluate this non-Maxwellian plasma beam, including a compensation of the secondary electron emission effect on the probe's surface. The results show prominent features on the extracted jet's kinetic energy and the respective (electron) current of IEC. In addition, they demonstrate a practical method to characterise non-Maxwellian plasma jets through Faraday probes.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 159〈/p〉 〈p〉Author(s): Mo-Lin Su, Jia-Ning Li, Ke-Gao Liu, Wen-Jun Qi, Fei Weng, Yuan-Bin Zhang, Ji-Shuai Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Vacuum electron beam welding (EBW) was used to weld the thick TA1 titanium alloy sheets. Test results indicated that the coarse serrated-shape α and needle-shape α′ grains were observed in weld zone (WZ); the heat affected zone (HAZ) near the weld center consisted of α and α′ gains; the tensile strength of the TA1 joint was 344 MPa, which was significantly higher than that of the base metal (BM); the fracture of the tensile samples with different penetration depths all occurred on BM, the tensile property of the upper-bottom joint was better than that of the middle joint; moreover, lots of dimples can be observed on the fatigue fracture surface, exhibiting the characterization of the ductile fracture.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 159〈/p〉 〈p〉Author(s): Denize Kalempa, Felix Sharipov, Júlio Conti Silva〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sound waves due to vibro-thermal excitation propagating through a binary mixture of rarefied gases in a gap between source and receptor are investigated by applying the McCormack model to the Boltzmann equation. The sound waves are induced by mechanical vibration and temperature variation of one plate, while the other plate being fixed at a constant temperature, acts as a receptor of sound waves. The oscillatory gas mixture flow is considered as fully established and all its macroscopic quantities depend on time harmonically. The discrete velocity method is used to solve the coupled kinetic equations in wide ranges of both rarefaction and oscillation parameters. The former is defined as the ratio of the distance between the plates to the equivalent free path, while the latter is the ratio of the intermolecular collision frequency to sound frequency. Analytical solutions in the free molecular and hydrodynamic regimes have been obtained too. Two mixtures, namely, Helium〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Argon and Helium〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Xenon, are considered with a molar fraction equal to 0.1, 0.5 and 0.9. The amplitudes and phases of all macroscopic characteristics of the gas mixture flow are calculated as functions of the rarefaction and oscillation parameters so that the free molecular, transitional and hydrodynamic regimes are covered. The results are compared to those obtained in the limit of a single gas in order to investigate the influence of the molar fraction and molecular masses of species on the problem solution. The reciprocal relations between cross phenomena are obtained and verified numerically.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Sunil Kumar, Vishal Sharma, P.K. Diwan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The energy loss straggling of 5.486 MeV α-particles in Tb, Ta and Au metallic foils (varying thicknesses ∼4.20–16.00 mg/cm〈sup〉2〈/sup〉) is measured, in the fractional energy loss limits (ΔE/E %) ∼20–85, using transmission technique. These measured straggling values are compared with the predicted values based on Bohr, Lindhard and Scharff, Bethe and Livingston, Yang et al. and Titeica analytical straggling formulas. The present comparison reveals that the prediction of Titeica straggling formula shows better agreement with the measured values as compared to other considered straggling formulas. Here, Titeica formula based predicted values show generally ∼0.60–1.30 times deviation with the presently measured straggling values.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Tong Zhao, Wangcan Cai, Marius Dahmen, Jonathan Schaible, Chen Hong, Andres Gasser, Andreas Weisheit, Tim Biermann, Ingomar Kelbassa, Han Zhang, Dongdong Gu, Johannes Henrich Schleifenbaum〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The use of aluminium alloys containing Sc and Zr in additive manufacturing (AM) provides new solutions for lightweight design. Representative thin-wall structured parts were additively fabricated with a commercially available Al-4.55Mg-0.51Mn-0.65Sc-0.30Zr alloy in Laser Metal Deposition (LMD) process. A bi-directional and a uni-directional scan strategy were applied and laser power from 500 W to 600 W was used. Nanohardness tests were conducted on specimens aged at 300 °C for up to 19 h to observe the ageing responses. Fine-grained microstructures with few micro-sized precipitates containing Sc- and Zr were found in the last track of every specimen. The area formed by the track-overlapping was the opposite, but an apparent hardening was observed only after the ageing. AM-processes with local remelting are facing the challenge to exert the potential strengthening effect of aluminium alloys containing Sc. The mushy state must be suppressed to prevent the waste of the expensive rare elements.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0042207X18309187-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Chander Prakash, Sunpreet Singh, Manjeet Singh, Kartikey Verma, Babulal Chaudhary, Subhash Singh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present research work is aimed to discuss a novel method of depositing hydroxyapatite coats, with interconnected pores, on the surface of bio-degradable Mg〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Zn〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Mn alloy by using hydxroxyapatite (HA) powder mixed electric discharge machining (HAM-EDM) process. The parameters of HAM-EDM process has been optimized using multi-objective particle swarm optimization (MO-PSO) technique to determine the optimal levels of concentration of hydroxyapatite powder (C〈sub〉HA〈/sub〉), peak-current (I〈sub〉p〈/sub〉), pulse-on (T〈sub〉on〈/sub〉), and pulse-off (T〈sub〉off〈/sub〉). The surface roughness (S〈sub〉R〈/sub〉), thickness of recast layer (R〈sub〉LT〈/sub〉), and micro-hardness (M〈sub〉H〈/sub〉) were chosen as output response characteristics. The experiments were performed according to L〈sub〉27〈/sub〉 orthogonal array and an empirical model has been developed to interpret the co-relation amongst input and output parameters. A number of optimal solutions (∼100) were obtained by MO-PSO technique, where all responses were optimized. Among them, best optimal condition is to deposit biomimetic HA-containing layer with low SR (0.70 μm), low RLT (11.85 μm) and high MH (246 HV) was C〈sub〉HA〈/sub〉 = 5.28 g/l, I〈sub〉p〈/sub〉 = 3.48 A, T〈sub〉on〈/sub〉 = 40.33 μs, and T〈sub〉off〈/sub〉 = 109.29 μs? Further, the specimens produced were characterized, morphologically and topologically, and revealed the existence of hydroxyapatite (HA) layer with interconnected pores of 5–10 μm size. The EDS spectrum showed that presence of Ca, P, and O on the modified surface, which conferred the deposition of HA-layer on the surface. The XRD pattern investigations of modified surface confirmed the formation of various biocompatible phases, which enhanced the mechanical properties, corrosion and osseintegration characteristics.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 13 April 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum〈/p〉 〈p〉Author(s): Refat El-Sheikhy, Akira Kobayashi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Observations on fracture and crack bifurcation phenomenon of plasma spray Zr coating is studied in current paper with new understanding based on new recognized information.〈/p〉 〈p〉A new model is developed for Zr coating layers and cracks. Analytical fundamental characterization is carried out regarding mechanism under high thermal stresses on outer face with cooling back side of the substrate. Results are new such as crack branches at 120°, layered cracks, stepped crack surface and variable crack width. The zirconia coating has hexahedral shape as a honeycomb microstructure. Due to effect of heating-cooling, the first coating layer and near layers to substrate surface of zirconia coating will be contracted or do not be expanded while outside coating layers will be extended producing bi-interfacial de-bonding between particles and propagation to other crystals producing cracks and branching. Depth and width of the crack will be extended and increased in the coating layers producing stepped and layered cracks with branches. Propagation angles of branches are always 60°. Cracking load will be maximum at main crack orientation angle of β = 45° for equal stresses in both X and Y directions while for β〈30, β〉60 cracking load will be minimized meaning that crack will carry high stresses at 30〉β 〉 60.〈/p〉 〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 12 June 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum〈/p〉 〈p〉Author(s): Akira Kobayashi〈/p〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Ayushi Paliwal, Monika Tomar, Vinay Gupta〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Surface Plasmon Resonance (SPR) technique has been used in the present work to study the optical properties of pulsed laser deposited single phase BiFeO〈sub〉3〈/sub〉, Mn doped BiFeO〈sub〉3〈/sub〉 (BFMO) and Ce doped BiFeO〈sub〉3〈/sub〉 (BCFO) thin films. Refractive index dispersion studies with varying incident wavelengths has also been studied. Magnetic field dependence on the optical properties of BFMO thin films have also been determined using SPR. A very high sensitivity of 147°/Tesla was found for the prism/Au/BFMO structure exhibiting maximum change in optical properties with magnetic field indicating the potential use of BFMO thin films for the realization of efficient optical sensor.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 159〈/p〉 〈p〉Author(s): Bo Gao, Xiaoye Du, Yangyang Liu, Baorui Song, Shuheng Wei, Yanhuai Li, Zhongxiao Song〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A superhydrophobic titanium dioxide (TiO〈sub〉2〈/sub〉) film with the template of a candle smoked Si wafer was successfully fabricated by magnetron sputtering. The film specimens were examined by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, contact angle meter, scanning electron microscope (SEM), transmission electron microscope (TEM) and gas-sensitivity tests. The results showed that the TiO〈sub〉2〈/sub〉 solely deposited on the silicon wafer was hydrophilic, with its contact angel only 61°, while it became superhydrophobic with water contact angle up to 155° after depositing on candle smoked substrate. The SEM and TEM results showed that the TiO〈sub〉2〈/sub〉 morphology kept the spongy-like framework covering on the carbon clusters formed template. In this paper, the superhydrophobic TiO〈sub〉2〈/sub〉 was achieved on the candle soot without modification by low surface energy materials, which shows the dominance of the structure for preparing hydrophobic TiO〈sub〉2〈/sub〉 films. The TiO〈sub〉2〈/sub〉 films deposited on the candle soot more excellent gas sensitivity than pure TiO〈sub〉2〈/sub〉 films.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): J.B. Mathangi, M. Sadeesh Sharma, B. Mercy Jacquline, M. Helen Kalavathy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Adsorption technique was employed to reduce the pollutants from the fluid phase. In this research work, Activated Carbon was produced by chemical activation of wood sawdust at different impregnation ratios and the yield, bulk density, methylene blue number, iodine number and pH point of zero charges were determined. The S〈sub〉BET〈/sub〉 for AC3H was found to be 797.73 m〈sup〉2〈/sup〉 g〈sup〉−1〈/sup〉. Batch adsorption for the removal of nickel was carried out to perform the isotherm and kinetic study by varying parameters such as contact time, initial metal ion concentration, carbon dosage and temperature. The maximum adsorption capacity of Ni〈sup〉2+〈/sup〉 onto adsorbent was 16.47 mg g〈sup〉−1〈/sup〉. The fixed bed adsorption was performed for parameters such as particle size of 1.7 mm, 1.4 mm & 0.6 mm and flow rate of 50 mL min〈sup〉−1〈/sup〉, 70 mL min〈sup〉−1〈/sup〉 and 90 mL min〈sup〉−1〈/sup〉 which in turn indicated favorable column dynamics and its CO〈sub〉2〈/sub〉 adsorptive behavior. The maximum equilibrium adsorption capacity for CO〈sub〉2〈/sub〉 adsorption obtained was 0.96 mol kg〈sup〉−1〈/sup〉 for the flow rate of 90 mL min〈sup〉−1〈/sup〉 and a particle size of 0.6 mm. Kinetic and dynamic models were fitted with the experimental data and the adsorption constants were determined.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: Available online 27 August 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum〈/p〉 〈p〉Author(s): Amodini Mishra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present work, magnetite (Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉) nanoparticles decorated graphene oxide (GO) sheets were synthesized using the chemical method. Graphene based nanocomposites show an effective adsorbent property, and therefore can be used as an organic pollutant remover from the aqueous medium. The X-ray diffraction analysis was done to investigate the crystallinity and particle size of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 decorated GO sheets and the particle size was found to be 28 nm. Surface morphology of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@GO nanocomposites was studied using transmission electron microscopy and the obtained inter planer spacing in Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@GO nanocomposites was 0.246 nm. For the applications point of view, these nanocomposites have been used for the removal of Rhodamine 6G dye molecules from the aqueous medium. The removal capacity was found to increase as the concentration of the nanocomposite increases. In Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@GO nanocomposites the GO sheets provide large surface area due to different functional groups like epoxide (C-O-C), carboxylic acid (-COOH), hydroxyl (-OH) to adsorb dye molecules. This study provides a new platform for the use of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@GO nanocomposites in a water clean-up process.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 159〈/p〉 〈p〉Author(s): Yanfei Pan, Bo Liu, Huixiang Hu, Haodong Jiang, Feng Wei, Min Zhou, Xinyan Fan, Haibiao Yu, Gengwu Niu, Jintian Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The rod-shaped Ni-NiO/TiO〈sub〉2〈/sub〉 hollow composite structure based on metallization cellulose fibers and Titanium butoxide (TBOT) via Sol-Gel method was fabricated to obtain a highly active rod-shaped hollow catalysts. The results showed that the high-heat treatment had no obvious influence on the hollow structure cavity size and the ideal surface roughness value of hollow structure was 6.385 μm. The XRD patterns revealed that the Ni and TiO〈sub〉2〈/sub〉 particles that had been deposited on cellulose fibers had a crystallite size structure between 16.5 and 19.4 nm. The characteristic absorption peak at 1035 cm〈sup〉−1〈/sup〉 assigned to Ti-O-C of anatase nano-TiO〈sub〉2〈/sub〉 on hollow structure surface appeared. It is feasible to control the crystallite size and hollow cavity pore size via Sol-Gel method. The magnetic hollow structure shown here can be applied as catalysts and it can be completely natural subsidence within 5 min. Herein, the catalytic capacity of the rod-shaped Ni-NiO/TiO〈sub〉2〈/sub〉 hollow composite structure for Cu (II) was found to be 5696 mg g〈sup〉−1〈/sup〉.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 159〈/p〉 〈p〉Author(s): Ben D. Beake, Adrian J. Harris〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉It is important to measure nanomechanical properties of materials for extreme environments at temperatures that match their operating conditions so that the data are more relevant than those obtained from room temperature measurements. Reliable high temperature mechanical property data improves our understanding of the linkage between the small-scale mechanical behaviour and the performance and design of advanced materials systems for increasingly extreme environments. Accurate high temperature nanomechanical measurements require significantly more careful instrumental and experimental design than at room temperature. It is important to consider (i) instrumental stability and thermal drift (ii) the test environment and its influence on the stability of the indenter and sample (iii) modifications to the experimental load history and analysis procedures to minimise the effect of greater time-dependency. In this review of best practice and published studies effective strategies for mitigating these effects and achieving reliable, validated data are discussed with illustrative examples on thin films and bulk materials operating in extreme environments in applications in the nuclear, aerospace, fuel cell and cutting tool industries to 1000 °C.〈/p〉〈/div〉 〈/div〉

Beschreibung: 〈p〉Publication date: December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Vacuum, Volume 158〈/p〉 〈p〉Author(s): Jiankun Qin, Xiaowan Li, Yali Shao, Kaixin Shi, Xin Zhao, Tianshi Feng, Yingcheng Hu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Transparent wood is an environmentally friendly material that could be used as building materials or substrates for solar cells to reduced electrical energy consumption. Many problems remain in the delignification process, such as energy consumption and gas pollution. In this paper, the optimum conditions for two stage delignification of low density balsa wood (〈em〉Ochroma pyramidale〈/em〉) and high density of basswood (〈em〉Tilia tuan〈/em〉) were studied. The optimized single layer transparent wood was laminated to produce transparent wood with high thickness. The results showed that the lamination method cut the delignification time in half and improved the dimensional stability of the transparent wood. Optical testing showed that the maximum transmittance of the same direction laminated transparent wood was similar to the single layer transparent wood with the same thickness. The mechanical experiments showed that the transparent basswood had a better tensile strength, which reached 75.12 MPa. Optimizing the process of the transparent wood could greatly reduce the preparation time and the energy consumption, so that mass production of enterprises could become a reality.〈/p〉〈/div〉 〈/div〉