ALBERT

Description: 〈h3〉Abstract〈/h3〉 〈p〉This work reported the structure and optical investigations of CdS〈sub〉1−〈em〉x〈/em〉〈/sub〉Mn〈sub〉〈em〉x〈/em〉〈/sub〉 (〈em〉x〈/em〉 = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10) thin films. The thin films of CdS〈sub〉1−〈em〉x〈/em〉〈/sub〉Mn〈sub〉〈em〉x〈/em〉〈/sub〉 with different compositions were synthesized using electron beam evaporation method under high vacuum conditions at room temperature. X-ray diffraction (XRD) analyses revealed the polycrystalline nature of the deposited films. The observed diffraction peaks were well fitted with a hexagonal crystal structure. In addition, the intensity of XRD peaks decreased by increasing the Mn concentration indicating a monotonical deterioration in the crystalline quality by the doping. The (101) plane is the preferential orientation for the crystal growth of the studied films. The film thickness as well as a refractive index were calculated by Swanepoel’s method. The direct and indirect electronic transitions were found to be responsible for the high absorption process in the studied films. Furthermore, both direct and indirect bandgaps decreased with increasing the Mn content. Other optical parameters such as optical conductivity, real and imaginary parts of dielectric constant, dispersion energy, and dissipation factor were determined and showed a strong dependence on the Mn content. These findings were discussed in terms of the localized states.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉To analyze the influence of processing conditions on the melt pool geometry and dilution ratio of the Ni-based alloy during laser cladding, a finite element model of heat transfer and fluid flow with multi-physical parameters was established. This model is used to simulate the temperature and velocity fields of melt pool. Thermodynamic processes such as phase transition, Marangoni convection and buoyancy were considered in this model. Adding materials in real time was considered by introducing powder feeding rate. The relative energy–mass ratio (REMR) was introduced to simplify process analysis, and the effects of different processing parameters on the dilution rate and on the melt pool geometry were explored through the established model. The results show that dilution ratio and REMR are linearly related within a certain range. In addition, due to the fluid flow, the boundary at bottom of melt pool changes gradually from shallow arc shape to wave shape, and finally to deep arc shape with increased REMR.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Energy absorption buildup factor (EABF) and exposure buildup factor (EBF) of bismuth borate glass systems in structure (75–〈em〉x〈/em〉)〈span〉 〈span〉\(\text {B}_2\text {O}_3\)〈/span〉 〈/span〉–〈span〉 〈span〉\(x\text {Bi}_2\text {O}_3\)〈/span〉 〈/span〉–〈span〉 〈span〉\(10\text {Na}_2\text {O}\)〈/span〉 〈/span〉–〈span〉 〈span〉\(10\text {CaO}\)〈/span〉 〈/span〉–〈span〉 〈span〉\(5\text {Al}_2\text {O}_3\)〈/span〉 〈/span〉 (〈span〉 〈span〉\(0\le {x} \le 25 \text { mol}\%\)〈/span〉 〈/span〉) have been investigated for photon energy region between 0.015 and 15 MeV and for penetration depths of 1–40 mfp. Five parameters (G–P) fitting method has been carried out for computations procedure. The calculated values of EABF and EBF have been observed to be dependent on photon energy, penetration depths and on the concentration of 〈span〉 〈span〉\(\text {Bi}_2\text {O}_3\)〈/span〉 〈/span〉 mol% in the glass sample. It has been found that BOB25 glass offers better gamma-ray shielding than other samples. In addition, the values of EABF and EBF have been compared and significant differences up to 〈span〉 〈span〉\(8\%\)〈/span〉 〈/span〉 have been noted in intermediate energy region.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In the silicon dicing processes, the laser induced thermal-crack propagation (LITP) has been reported about its superiority over traditional dicing methods in aspect of crack surface quality and mechanical properties. However, this process may cause deviation of its propagation path especially under the condition of asymmetric linear cutting. Aiming to solve the path-deviation problem, a method of pre-crack on the surface of the silicon wafer has been proposed. A mathematical model which consists absorption of laser, heat transfer, generation of thermal stress, and crack initiation and propagation, has been established. Numerical simulation in the LITP of silicon wafer with respect to two pre-crack modes: pre-crack on the end and pre-crack on the surface were conducted to study the high-quality crack propagation mechanism. Unbiased crack propagation was found in the simulation of pre-crack on the surface process and the mechanism of it was revealed through the analysis of the tensile stress distribution. It was found that the three-dimensional shape of the tensile stress at the front of the crack tip would result in an uncertain propagation in conventional LITP of pre-crack on the end. Conversely, the slice shape of the tensile stress would induce a certain propagation direction that was along the plane of the pre-crack in the simulation of pre-crack on the surface. The experimental results verified the unbiased propagation mode and showed good crack surface quality.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Typically, low cost as well as stability factors of the organo-metal halide perovskite solar cells based on inorganic hole transport layers (HTLs) have been the focus of intense research over the past few years. Accordingly, the power conversion efficiencies have rapidly been improved to ~ 20% with high stabilities. Therefore, this review covers the major advances of inorganic HTLs in perovskite solar cells that have contributed to the recent efficiencies and stabilities, including the evolution of device architecture, the development of hole transport material deposition processes, synthesis, morphology and the interface properties between inorganic HTLs and perovskite layers. Eventually, the challenges and future directions for inorganic HTLs-based perovskite solar cells are also discussed.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Spinel ferrites at nanoscale showed quite different properties rather than the bulk counterpart. Among all the ferrites, ZnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 compound is chemically stable and showed very good properties at room temperature. In this investigation, we reported the synthesis and characterization of ZnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 single-phase crystals of diameter 11 nm by solvothermal reflux method. Temperature-dependent dielectric constant, dielectric loss, and ac-electrical conductivity of the pellet were measured up to 450 °C under different alternating electric field frequencies from 1 kHz to 1 MHz. The obtained data revealed interfacial or space charge polarization mechanism. Furthermore, the sample showed superparamagnetic nature at room temperature. In addition, the magnetic hyperthermia value and specific heat generation rate (SHGR) of 128.76 J s〈sup〉−1〈/sup〉 g〈sup〉−1〈/sup〉 for ZnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 compound at 1 mg mL〈sup〉−1〈/sup〉 concentration were evaluated. The data were interpreted by spin-relaxation mechanism. ZnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanoparticles showed good photocatalytic activity under UV light irradiation. The data were interpreted by electron–hole pair and radical formation and degradation of Rhodamine B dye.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this work, homogeneous PVC/MWCNT nano-composite films with different concentrations of MWCNTs were prepared. The MWCNTs were treated with plasma to improve their compatibility in the PVC matrix. The prepared films are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV–visible spectroscopy (UV–Vis.) and thermogravimetric analysis (TGA). The XRD, XPS, FTIR and Raman results suggest that the plasma-functionalized MWCNTs are well dispersed and interacted with the PVC. XPS results show that the stoichiometric contents of C and O groups relatively increased with the increasing percentage of MWCNTs in the nano-composite, meanwhile, Cl group decreased. The optical band gap 〈span〉 〈span〉\(E_{\mathrm{g}}\)〈/span〉 〈/span〉 of PVC–MWCNTs decreases with the increasing MWCNTs percentage in the nano-composite. Increasing the percentage of MWCNTs in the PVC nano-composite improves thermal stability, dielectric constant and AC conductivity.〈/p〉

Description: 〈p〉In the originally published version of this article the acknowledgement was missing.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Corn starch and citric acid, two low-cost and abundant materials, were used for establishing a novel screen printable hydrogel for printed electronics applications. Corn starch was modified with citric acid by melt-blending; the so obtained thermoplastic starch was ground to powder and added to a water–starch suspension. Ultrasonication was used to prepare hydrogels of different citric acid concentrations. The most promising hydrogel contained 10% citric acid by weight, provided an ionic conductivity of (2.30 ± 0.07) mS cm〈sup〉−1〈/sup〉 and appropriate rheological properties for screen and stencil printing. The hydrogel shows superb printability and prolonged stability against degradation. The corn starch hydrogel was used as printable gel polymer electrolyte in fully printed supercapacitors. The specific capacitance of the printed supercapacitor reached 54 F g〈sup〉−1〈/sup〉. The printable hydrogel-polymer electrolyte is easy to produce without in-depth chemical knowledge, is based on widely used and non-toxic materials, and may be used as a functional layer in other printed electronics applications such as printed batteries.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, we report the fabrication of a high-sensitivity strain sensor fabricated using graphene platelets (GnPs) and multi-walled carbon nanotubes (MWCNTs) for monitoring joint-bending movement. The optimized ultrasonic time and the ball mill-mixing process make the GnPs disperse evenly in the MWCNTs. The strain sensor made up of the GnP/MWCNT mixture (30 wt% GnPs loading) is fabricated by a spray-method and its conductivity is up to 10〈sup〉4〈/sup〉 S/m. The as-prepared GnP/MWCNT sensor exhibits relatively high tensile strength of 5.4 MPa, sensing range of 7.5%, gauge factor of 181.36, linearity of 99.545%, and great bending reproducibility over 5000 cycles. These remarkable features endow our sensing devices to monitor joint bending in human health monitoring, e.g., elbow, finger and wrist bending. The results demonstrate that our flexible GnP/MWCNT sensor shows promising applications prospects in smart wearable device monitoring human health.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The present study is concerned with the synthesis and characterization of rare-earth-doped SrM (Sr〈sub〉1-〈em〉x〈/em〉〈/sub〉RE〈sub〉〈em〉x〈/em〉〈/sub〉Fe〈sub〉12〈/sub〉O〈sub〉19〈/sub〉) hexaferrites (RE = La, Ce and Tb; 〈em〉x〈/em〉 = 0, and 0.1). The hexaferrite precursor powders were prepared by high-energy ball-milling and sol–gel auto-combustion methods, and the powders were sintered at temperatures ≥ 900 °C. The effects of RE substitution and synthesis route on the structural and magnetic properties of SrM hexaferrites were investigated by X-ray diffraction, scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). Single SrM phase was obtained in the sample with 〈em〉x〈/em〉 = 0, and the sample with La substitution was prepared by ball-milling method. The rest of the samples, however, contained small amounts of minor phases of rare-earth oxides and α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 in addition to the major SrM phase. SEM imaging revealed significant decrease in particle size with RE substitution. Also, VSM measurements revealed small decrease in the saturation magnetization, and a significant increase in the coercivity with RE substitution. Comparable saturation magnetization was observed for the samples prepared by sol–gel method, whereas the coercivity increased significantly. The coercivity of samples prepared by sol–gel method exhibited a large increase with the decrease in sintering temperature, reaching ~ 6.2 kOe for the samples with Ce- and Tb-substituted samples sintered at 900 °C. The relatively high remnant magnetization (~ 30–35 emu/g) and high coercivity make these materials important candidates for permanent magnet applications.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Poly (acrylonitrile) (PAN), acetylene black (AB) and graphene oxide (GO), as conductive constituents, were mixed with sulfur by solution-processing technique using dimethyl sulfoxide as a solvent. The physical properties of the as prepared composites were characterized by X-ray diffraction, Raman and scanning electron microscope analysis. The electrochemical property of S/GO composite material exhibits better cyclical stability. The first-cycle capacity obtained by S/GO composite was 937 mAh g〈sup〉−1〈/sup〉 at 0.1 C with coulombic efficiency of 98% and good cycle ability around 813 mAh g〈sup〉−1〈/sup〉 discharge capacity at the 50th cycle which is higher than of S/PAN and S/AB composite.〈/p〉 〈span〉 〈h3〉Graphic abstract〈/h3〉 〈p〉 〈span〉 〈span〉 〈img alt="" src="https://static-content.springer.com/image/MediaObjects/339_2019_2758_Figa_HTML.png"〉 〈/span〉 〈/span〉 〈/p〉 〈/span〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Organic semiconductor charge transport layers are important constituents of perovskite-based solar cells. To assess the suitability of potential solvents for the deposition of the charge transport layers on perovskite surfaces, the effect of solvent exposure on the properties of methyl ammonium lead mixed halide CH〈sub〉3〈/sub〉NH〈sub〉3〈/sub〉PbI〈sub〉3–〈em〉x〈/em〉〈/sub〉Cl〈sub〉〈em〉x〈/em〉〈/sub〉 films is investigated by grazing incidence X-ray diffraction, atomic force microscopy, ultraviolet–visible absorption spectroscopy, and photoelectron spectroscopy. While exposure to dimethylformamide (DMF) and water instantly dissolves the perovskite film, exposure to chlorobenzene (CB) and chloroform (CF) does not detectably affect the perovskite bulk properties. However, the electronic properties of the perovskite surface are substantially modified by the solvent exposure, resulting in an increased work function and less n-type appearance.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Thin films of copper zinc tin sulfide (CZTS) have been synthesized on glass substrates at various thickness layers by change in number of layer from 3, 5 and 7 layers using sol–gel spin coating deposition technique. SEM photos were demonstrated for different thickness layer at constant temperature 280 °C. According the EDX analysis thin films exhibit nearly stoichiometry with 1.1 and (0.5–0.8) atomic ratio Cu/(Zn + Sn) and Cu/Zn, respectively. XRD pattern of the prepared CZTS films Show that the films have relatively high intensity peaks at 28.5° for 3 layer and 29.8° for 5 layers of 2〈em〉θ〈/em〉 value corresponding to (112), (220) and (312) phase, respectively. As the thickness layer of the synthesized CZTS films increases to 7 thickness layer, the film structure tends to be amorphous at the same temperature 280 °C, so the films were annealed to temperature 360 °C and 400 °C for a better crystallization state. The optical band gab is found in the range 1.5–1.8 eV and observed to decrease with thickness layer increasing. Additionally, the effect of the annealing temperature on the morphology and the energy gap for a film of 7 layer thicknesses at various temperatures from 280 to 400 °C was performed.〈/p〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉Al–Co–Cr–Fe high-entropy alloy coatings were laser additively produced on aluminum substrate under different laser fluences (17.0–21.2 J/mm〈sup〉2〈/sup〉). The resultant coatings consisted of a mixture of high-entropy and intermetallic phases, which resulted in marked improvement in hardness (~ 275–500 HV) as compared to the aluminum substrate (~ 30 HV). Coating corresponding to higher laser fluences showed lower corrosion currents (〈em〉I〈/em〉〈sub〉corr〈/sub〉 ~ 3.6 × 10〈sup〉−4〈/sup〉 mA/cm〈sup〉2〈/sup〉) and higher linear polarization resistance (LPR) of ~ 14–16 kΩ/cm〈sup〉2〈/sup〉 as compared to the aluminum substrate (〈em〉I〈/em〉〈sub〉corr〈/sub〉 ~ 7×10〈sup〉−4〈/sup〉 mA/cm〈sup〉2〈/sup〉) and ~ 11 kΩ/cm〈sup〉2〈/sup〉 in 0.6 M NaCl solution. The behavior of surface properties was analyzed in relation to the variation in fraction of HEA and intermetallic phases within the coatings resulting due to increased content of Al from the Al substrate with an increase in the laser fluence. The coating consisting of optimal amount of HEA and intermetallic phases showed a tenfold decrease wear volume loss (0.01 mm〈sup〉3〈/sup〉) as compared to Al substrate showing 0.11 mm〈sup〉3〈/sup〉.〈/p〉 〈/span〉 〈span〉 〈h3〉Graphical abstract〈/h3〉 〈p〉 〈span〉 〈span〉 〈img alt="" src="https://static-content.springer.com/image/MediaObjects/339_2019_2573_Figa_HTML.png"〉 〈/span〉 〈/span〉 〈/p〉 〈/span〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Ferritin is an iron storage protein found in living organisms. It is an antiferromagnetic nanoparticle system consisting of an inorganic core surrounded by a protein shell. Ferritin is characterized by X-ray diffractometer, transmission electron microscope, atomic absorption spectrometer and thermogravimetric analyzer. We find that the ferritin core is poorly crystalline, 8 nm in size and consists of 10 wt% iron. It is believed that cores of ferritin consist of single-phase inorganic mineral ferrihydrite. Recently, we have shown that ferrihydrite decomposes directly to 〈span〉 〈span〉\(\alpha\)〈/span〉 〈/span〉-〈span〉 〈span〉\(\hbox {Fe}_{{2}}\hbox {O}_{3}\)〈/span〉 〈/span〉 on heating in air at 440 〈span〉 〈span〉\(^{\circ }\)〈/span〉 〈/span〉C. In the present work, we show that ferritin cores gradually decompose to a mixture of 〈span〉 〈span〉\(\gamma\)〈/span〉 〈/span〉-〈span〉 〈span〉\(\hbox {Fe}_{{2}}\hbox {O}_{{3}}\)〈/span〉 〈/span〉 and 〈span〉 〈span〉\(\alpha\)〈/span〉 〈/span〉-〈span〉 〈span〉\(\hbox {Fe}_{{2}}\hbox {O}_{{3}}\)〈/span〉 〈/span〉 on heating in air. This mixture finally stabilizes to 〈span〉 〈span〉\(\alpha\)〈/span〉 〈/span〉-〈span〉 〈span〉\(\hbox {Fe}_{{2}}\hbox {O}_{{3}}\)〈/span〉 〈/span〉 on further heating. The magnetic behaviour of final sample is also studied. This work confirms that the ferritin cores contain more than one phase.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉We have studied the thin films of P3HT:PCBM and P3HT:ITIC blends as a prospective active layer for Organic Solar Cells by absorption, photoluminescence, and short-circuit current density–voltage characteristics. The potential estimation of structural changes in such photovoltaic devices is shown by employing the variations in absorption and photoluminescence spectra. The comparative analysis of key features of the absorption and photoluminescence spectra can be used as an indicator of their structural and photophysical properties.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉β-Ga〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanowire (NW) was fabricated on a Si-substrate using glancing angle deposition (GLAD) technique. To study the structural, morphological, and optical properties of the as-deposited β-Ga〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 NW, thermal annealing was done at different temperatures ranging from 600 to 1000 °C and the corresponding results were analyzed. XRD analysis shows an increase in crystallinity of the as-deposited sample upon annealing. The average crystallite size was found to be increased from 13.72 to 20.19 nm after annealing at 900 °C. Annealed β-Ga〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 NW contains more concentration of oxygen due to absorption of O〈sub〉2〈/sub〉 molecules. The lattice strain and dislocation density of the as-deposited β-Ga〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 NW were found to reduce significantly after thermal annealing. The FEG-SEM image confirms the growth of vertically aligned β-Ga〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 NW. An enhancement in the UV region was observed in the photoluminescence spectra after annealing at 900 °C.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The propagation of surface acoustic wave (SAW) on the piezoelectric substrate requires conventionally an interdigitated electrode structure to excite the mechanical displacement at resonance frequency. The control of the electrode thickness could be useful to manipulate the energy confinement and the band dispersion of the surface guided mode. It has been demonstrated recently that high aspect ratio (HAR) electrode could produce a dispersive shear horizontal and vertically polarized surface modes in the bulk piezoelectric substrate. In this theoretical study, we propose to employ a high aspect ratio electrode on top of the GaN/sapphire-layered substrate enabling the presence of Sezawa surface mode. Based from the dispersion band, we obtained a higher frequency of surface guided mode in the non-radiative zone in the GaN/sapphire heterostructure configuration compared to the bulk GaN substrate. Indeed, these guided modes are induced by the hybridization between Sezawa surface mode and the mechanical resonance of the HAR electrode producing nearly a flat band at the limit of First Brillouin Zone. Furthermore, the displacement of each guided modes indicates the confinement of energy mostly in the electrode with a slight amount of energy in the top layer of the substrate. We demonstrated also the frequency tuning of guided mode using diverse materials for the electrode but also the thickness of GaN layer. The obtained results could be useful for the development of high-frequency telecommunication and sensing device based on Sezawa surface acoustic wave.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This work aimed to investigate alpha, proton, neutron and gamma shielding qualifications of different bulk metallic glasses (Zr〈sub〉65〈/sub〉Al〈sub〉7.5〈/sub〉Ni〈sub〉10〈/sub〉Cu〈sub〉17.5〈/sub〉, Ti〈sub〉40〈/sub〉Zr〈sub〉26〈/sub〉Be〈sub〉28〈/sub〉Fe〈sub〉6〈/sub〉, Cu〈sub〉49〈/sub〉Hf〈sub〉42〈/sub〉Al〈sub〉9〈/sub〉, Pd〈sub〉40〈/sub〉Ni〈sub〉40〈/sub〉P〈sub〉20〈/sub〉, Ni〈sub〉50〈/sub〉Pd〈sub〉30〈/sub〉P〈sub〉20〈/sub〉, and Ca〈sub〉65〈/sub〉Mg〈sub〉15〈/sub〉Zn〈sub〉20〈/sub〉) for nuclear security applications. Therefore, vital gamma radiation attenuation parameter namely mass attenuation coefficients (〈span〉 〈span〉\(\mu_{\rho }\)〈/span〉 〈/span〉) of investigated bulk metallic glasses (BMG) were determined using WinXCOM program. Next, half value layer (HVL), effective atomic number (〈em〉Z〈/em〉〈sub〉eff〈/sub〉), effective electron density (〈em〉N〈/em〉〈sub〉el〈/sub〉) and exposure buildup factors (EBF) were perused in a wide energy interval (0.02–20 MeV). Among the investigated samples, MG3 was found to be superior attenuator sample for gamma radiation, while MG6 was the least forceful glasses to reduce the photon intensity. The elements Pd and Hf in MG4, MG5 and MG3 were enhanced radiation shielding competences of the BMGs. Further, fast neutron removal cross-sections (〈span〉 〈span〉\(\sum R\)〈/span〉 〈/span〉) were evaluated to investigate neutron protection ability of the BMGs. Projected range (PR) and mass stopping power (MSP) values were obtained for proton (H〈sup〉1〈/sup〉) and alpha particles (He〈sup〉+2〈/sup〉). The outcomes showed that elemental composition of the metallic glasses was highly powerful on alpha, proton and neutron attenuation. It can be concluded that MG3 sample exhibited high nuclear shielding efficiency as deduced from the largest 〈span〉 〈span〉\(\mu_{\rho }\)〈/span〉 〈/span〉, Z〈sub〉eff〈/sub〉, and 〈span〉 〈span〉\(\sum R\)〈/span〉 〈/span〉, and the lowest HVL, EBF, MSP and PR values.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The authors aim to study the gamma-rays and neutron beam shielding capabilities of zinc bismuth borate glasses doped with erbium ions. Mass attenuation coefficient (MAC) (〈em〉μ〈/em〉/〈em〉ρ〈/em〉) values were computed employing XCOM and two different simulation codes, MCNP5 and Geant4, within 0.015–15 MeV photon energy, which showed good agreement within the derived values. The effective atomic number (〈em〉Z〈/em〉〈sub〉eff〈/sub〉), electron density (〈em〉N〈/em〉〈sub〉e〈/sub〉), half-value layer (HVL) and mean free path (MFP) values were derived using MAC values. To account on the scattering effects of photons from the samples, exposure buildup factor (EBF) were determined, applying geometric progression (G-P) method, within 0.015–15 MeV photon energy and penetration depth of 1–40 mfp (intervals: 1, 5, 10, 15, and 40 mfp). The high MAC, 〈em〉Z〈/em〉〈sub〉eff〈/sub〉 values and low HVL, MFP values of 16.93B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉‒22.57ZnO‒60Bi〈sub〉2〈/sub〉O〈sub〉3〈/sub〉‒0.5Er〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 (mol%) glass optimized its shielding effects against gamma-rays. The macroscopic effective removal cross-section for fast neutron (Σ〈sub〉R〈/sub〉) values lie within the range of 0.1142–0.1232 cm〈sup〉−1〈/sup〉 for the selected Er〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-doped samples. The studied parameters of the experimented glasses revealed their dominant radiation shielding features compared to commercial shielding glasses, concretes, and alloys.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉We investigate the structural, magnetic, electronic, and mechanical properties of the full Heusler alloys (FHAs) Ti〈sub〉2〈/sub〉CoTl〈sub〉1−〈em〉x〈/em〉〈/sub〉Pb〈sub〉〈em〉x〈/em〉〈/sub〉 (〈em〉x〈/em〉 = 0.00, 0.25, 0.50, 0.75, 1.00) using first-principles calculations. The FHAs Ti〈sub〉2〈/sub〉CoTl〈sub〉1−〈em〉x〈/em〉〈/sub〉Pb〈sub〉〈em〉x〈/em〉〈/sub〉 have the half-metallic characters within lattice constant regions 5.799–6.707, 5.749–6.821, 5.749–6.982, 5.789–7.115, and 5.976–6.943 Å for 〈em〉x〈/em〉 = 0.00, 0.25, 0.50, 0.75, and 1.00, respectively. The negative formation energy, positive cohesion energy, and higher than room temperature Curie temperature indicate that the FHAs Ti〈sub〉2〈/sub〉CoTl〈sub〉1−〈em〉x〈/em〉〈/sub〉Pb〈sub〉〈em〉x〈/em〉〈/sub〉 are thermodynamically stable and can be used in spintronics and magnetoelectronics. The total magnetic moment per formula unit 〈span〉 〈span〉\(\mu_{\text{t}}\)〈/span〉 〈/span〉 of the FHAs Ti〈sub〉2〈/sub〉CoTl〈sub〉1−〈em〉x〈/em〉〈/sub〉Pb〈sub〉〈em〉x〈/em〉〈/sub〉 satisfies the Slater–Pauling rule 〈span〉 〈span〉\(\mu_{\text{t}} = Z{}_{\text{t}} - 18\)〈/span〉 〈/span〉, where 〈span〉 〈span〉\(Z_{\text{t}}\)〈/span〉 〈/span〉 represents the total number of valence electrons per formula unit. With increasing Pb atom concentration 〈em〉x〈/em〉, the band structures in both spin-up and spin-down channels move toward low energy region, but the spin-down indirect band gap 〈span〉 〈span〉\(E_{g}^{ \downarrow }\)〈/span〉 〈/span〉 increases. In addition, the calculated elastic constants and elastic modulus indicate that the FHAs Ti〈sub〉2〈/sub〉CoTl〈sub〉1−〈em〉x〈/em〉〈/sub〉Pb〈sub〉〈em〉x〈/em〉〈/sub〉 have mechanical stability, as well as ductility and strong resistance to fracture and plastic deformation.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉For this proposed work, the electrical and ferroelectric properties of metal–ferroelectric–insulator–silicon (MFeIS) and metal–ferroelectric–insulator–metal (MFeIM) capacitors with Bi〈sub〉4〈/sub〉Ti〈sub〉3〈/sub〉O〈sub〉12〈/sub〉 (BIT) ferroelectric film deposited on HfO〈sub〉2〈/sub〉/Si substrate were investigated. Physical vapor deposition technique (RF sputtering) was carried out for the deposition of 100 nm ferroelectric and high-k dielectric film of 5, 10 and 15 nm thickness. The structural properties such as crystallographic phase, grain size with composition and refractive index of the deposited films were measured by X-ray diffraction, field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM-EDS) and multiple angle ellipsometry. Metal/ferroelectric/silicon (MFeS), metal/ferroelectric/metal (MFeM), metal/insulator/silicon (MIS), MFeIS and MFeIM structures were fabricated to obtain the electrical and ferroelectric properties. Investigation shows that the MFeIS structure with 10 nm buffer layer demonstrates improved memory window of 8.81 V as compared to the 3.3 V in the MFeS structure. MFeIM with 10 nm HfO〈sub〉2〈/sub〉 buffer layer shows maximum remnant polarization of 4.05 μC/cm〈sup〉2〈/sup〉. MFeI (10 nm) S structure even shows endurance higher than 10〈sup〉13〈/sup〉 read/write cycles and data retention for more than 10 years. The reliability of the ferroelectric and ferroelectric/dielectric stack was obtained by measuring the breakdown voltage characteristics.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this work, a reduced graphene oxide (0, 10, 30, 50 and 70 wt%) functionalized with Cu〈sub〉0.3〈/sub〉Mn〈sub〉0.7〈/sub〉Fe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 (CMFO) nanocomposites (rGO/CMFO) was successfully prepared by two techniques, namely modified Hummers (rGO) and sol–gel auto-ignition techniques (CMFO). The structure, morphology, magnetic and electrical properties of obtained nanocomposites have been examined using X-ray diffraction technique, Raman radiation spectroscopy, high-resolution transmission electron microscopy and vibrating sample magnetometer. The increase of rGO decreases the particle size of CMFO. It also results in a decrease in the saturation magnetization of the composites from 37.96 to 13.29 emu/g. The coercivity of composites elucidated higher values than those of the pristine composite due to interface interaction between CMFO and rGO. Colossal enhancement in electrical conductivity, dielectric constant and dielectric loss occurred with increasing the rGO content. These results indicate that rGO/CMFO composites can be a good candidate for many electronic applications such as spintronic magnetic storage, high-energy storage device and microwave absorption material.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉ZnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/SnO〈sub〉2〈/sub〉 semiconductor nanocomposites with various mole ratios were prepared by a simple chemical synthesis process that based on sol–gel method. The structural properties were determined by X-ray diffraction and scanning electron microscope technique. The XRD study reveals that no impurity phase, such as ZnO, Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, existed in all the samples. The average grain size was found to be about 39.51 nm when the mole ratio of ZnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/SnO〈sub〉2〈/sub〉 is 2:1 (Z2S1), which is benefit for improving gas sensing property. The Z2S1 sample showed a relatively higher response (11.46) at a lower working temperature (176 °C) to acetone compared with other composites, and the response/recovery time were both very short. The improving gas sensing properties may be due to the fine grain and the formation of the ZnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉/SnO〈sub〉2〈/sub〉 heterojunction structure.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Nanocrystalline MgZn〈sub〉(1−〈em〉x〈/em〉)〈/sub〉O:〈em〉x〈/em〉Cr〈sup〉3+〈/sup〉 powders with 0.25 ≤ 〈em〉x〈/em〉 ≤ 3.0 mol% were synthesized using the combustion method. Crystallization of MgZn〈sub〉(1−〈em〉x〈/em〉)〈/sub〉O:〈em〉x〈/em〉Cr〈sup〉3+〈/sup〉 was investigated using the X-ray diffraction (XRD) technique which point towards significant reduction in crystallite size for MgZnO samples with increasing Cr〈sup〉3+〈/sup〉 concentration. Transmission electron microscopy revealed nanosized grains of the powder. UV–Vis spectroscopy and photoluminescence spectroscopy were employed to establish the electronic and optical properties of nanoparticles. Doping of Cr content from 0.25 to 3 mol% MgZnO facilitated tuning of bandgap in the range 3.37–3.43 eV. In addition to this, PL properties of the samples show that MgZn〈sub〉(1−〈em〉x〈/em〉)〈/sub〉O:〈em〉x〈/em〉Cr〈sup〉3+〈/sup〉 possess emission peak at 589 nm. Under excitation at 325 nm, the material exhibits an orange emission with highest relative intensity achieved for 0.25 mol% Cr〈sup〉3+〈/sup〉. This material may be explored as a new phosphor to be excited by UVA emitting AlGaN LEDs for optical devices and displays.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉To realize double-band perfect absorption, in this paper, we present a theoretical study of plasmonic absorption based on a metal–dielectric grating nanostructure. The structure consists of subwavelength periodic 〈span〉 〈span〉\( {\text{Al}}_{2} {\text{O}}_{3} \)〈/span〉 〈/span〉 grating covered with metal grating with a metal substrate. Results show that the one of the two absorption bands is caused by the Fabry–Perot resonance in the gold grating slits, and the other absorption band is caused by the gap plasmonic resonance of the 〈span〉 〈span〉\( {\text{Al}}_{2} {\text{O}}_{3} \)〈/span〉 〈/span〉 dielectric grating. The effect of structural parameters on absorption is also studied, the field distribution of the proposed nanostructure is presented to illustrate the absorption mechanism. Moreover, the two absorption peaks can be adjusted individually with different geometrical parameters. The results will pave the way towards the design of double-band plasmonic perfect absorber, which may have potential application in plasmonic absorption switch, plasmonic sensors and photodetectors.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The effect of germanium doping on the properties of hexagonal boron nitride and graphene monolayers was investigated using ab initio calculations. For boron nitride, the obtained results indicate the formation of electronic states in the region of the gap, near the Fermi level. The incorporation of such impurity atoms also induces an apparent decrease in the energy gap and a significant reduction in the optical conductivity. The calculations indicate small absorbance for wavelengths from infrared to visible light. For the graphene layer, it has been obtained a null gap semi-metal material. This result can be associated with the corresponding displacement of the Fermi level. In addition, the germanium doped graphene shows similar optical properties when compared with the pristine layer.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The effect of strain on the electronic and optical properties of ATaO〈sub〉2〈/sub〉N (A = Ca, Sr and Ba) is investigated using the first-principles hybridization functional calculations. The electronic and optical properties under the strains of − 8 to  + 8% in (100) and (010) directions are investigated. The results demonstrate that the band energy gap, band edges, absorption, reflectivity, and refractive index are obviously affected by the strains. Moreover, the effects of strains in (100) direction on all the considered properties of ATaO〈sub〉2〈/sub〉N are more obvious than those in (010) direction. The enhanced absorption in the visible light region is also found, which implies that ATaO〈sub〉2〈/sub〉N can well respond to the visible light. The present findings could provide a helpful reference to design photoelectronic materials with ATaO〈sub〉2〈/sub〉N by strain engineering.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉We report on the systematic first-principle calculations of the formation volumes of a single Fe (neutral iron) in Si〈sub〉1−〈em〉x〈/em〉〈/sub〉Ge〈sub〉〈em〉x〈/em〉〈/sub〉 at various Ge compositions (〈em〉x〈/em〉 = 4.7–20.3%). The formation volume was defined as the derivative of the Fe formation energy with respect to the pressure within 0–0.8 GPa. Interestingly, the formation volume was found to be equivalent to the difference between the volumes of the relaxed bulk and defective structures. The formation volume versus ‘〈em〉x〈/em〉’ exhibited a nonlinear pattern with regions of Fe-induced volume contraction (within 〈em〉x〈/em〉 〈 50%, i.e., Si-rich region) and expansion (〈em〉x〈/em〉 〉 50%, i.e., Ge-rich region). These results explain the reported observation that Fe prefers Si-rich environment and that Ge does not favor to be a nearest neighbor to Fe.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This paper presents the role of the conventional and Soliton wave model deposition at low substrate temperature (300–100 K) on the structural, electric and magnetic properties of Co〈sub〉35〈/sub〉Fe〈sub〉65〈/sub〉 thin films deposited by thermal evaporation using bulk polycrystalline Co〈sub〉35〈/sub〉Fe〈sub〉65〈/sub〉 alloy. On account of obtaining superior quality magnetic thin films without any high temperature growth processes or heat treatment, the Soliton wave growth model at suitable low temperature range is used. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques are employed to investigate the various structural properties. Morphological and structural analyses of entire 30 nm Co〈sub〉35〈/sub〉Fe〈sub〉65〈/sub〉 thin films deposited on Si (100) substrate reveal that the stoichiometry is preserved over the whole temperature deposition and BCC crystalline formed with (110) texture. To attain the electrical and magnetic properties, resistivity and vibrating-sample magnetometer (VSM) measurements are evaluated. Soliton wave model deposition significantly increased magnetic anisotropy constant 〈em〉K〈/em〉〈sub〉1〈/sub〉 = 0.105 Merg/cm〈sup〉3〈/sup〉, 〈em〉M〈/em〉〈sub〉R〈/sub〉/〈em〉M〈/em〉〈sub〉S〈/sub〉 = 0.83 and coercivity 〈em〉H〈/em〉〈sub〉C〈/sub〉 = 272 Oe at 300 K when the compared to conventional deposition range in this work (〈em〉K〈/em〉〈sub〉1〈/sub〉 = 0.014 Merg/cm〈sup〉3〈/sup〉, 〈em〉M〈/em〉〈sub〉R〈/sub〉/〈em〉M〈/em〉〈sub〉S〈/sub〉 = 0.6 and 〈em〉H〈/em〉〈sub〉C〈/sub〉 = 50 Oe). Growth with novel approach of Co〈sub〉35〈/sub〉Fe〈sub〉65〈/sub〉 thin films highlights the reasonable low coercivity, the high saturation magnetization, the high magnetic anisotropy and the low electrical resistivity values, with tailored grain size, make them feasible to use in magnetic sensor technology in the near future.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Sewage not only contains water-soluble contaminants but water-insoluble contaminants as well. Superhydrophobic CdS–melamine foam prepared in this research satisfies the requirements of water purification. The photocatalyst CdS effectively adsorbs light energy to generate active species (⋅O〈sub〉2〈/sub〉〈sup〉−〈/sup〉) for degrading water-soluble pollutants. At the same time, superhydrophobic/superoleophilic characteristic of the melamine sponge can be utilized to remove water-insoluble pollutants. Finally, the degradation mechanism of materials was obtained by studying the parameters such as band gap and valence band structure, as well as by analyzing the experimental data of active species.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This work presents a physics-based analytical modeling methodology for the prediction of the lack-of-fusion porosity in powder bed metal additive manufacturing (PBMAM) considering the molten pool geometry, powder size variation, and packing. The presented model has promising short computational time without resorting to the finite element method or any iteration-based simulations. The temperature profiles were calculated using a closed-form temperature solution. Multiple transverse sectional areas of the molten pool geometry were plotted on a cross-sectional area of the part based on hatch space and layer thickness to calculate the lack-of-fusion area. The powder bed porosity was calculated using advancing front approach with consideration of powder statistical distribution and powder packing. The part porosity was converted from the calculated lack-of-fusion area by multiplying the calculated powder bed porosity. Acceptable agreements were observed upon validation against experimental measurements under various process conditions in PBMAM of Ti6Al4V. The computational time was recorded less than 26 s for the porosity calculation of five consecutive layers. The presented model has high prediction accuracy and high computational efficiency, which allow the porosity calculation for large-scale parts and process parameters planning through inverse analysis, and thus improves the usefulness of analytical modeling in real applications.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The mixture of the Ti–Mo–Nb–Al–Si matrix powder and Carbon nanotubes (CNTs) particles was used as the starting powder to produce the in-situ TiC reinforced TMCs using reaction synthesis method. The effect of the adding various CNTs content on the microstructure, phase composition, hardness, and oxidation behavior of the composites was investigated. The results show that the phases of the composites were composed of mainly α-Ti, β-Ti and TiC. With the increase of adding CNTs content, the porosity increased gradually, and the hardness initially increased and then decreased. The hardness of the composites with adding 1.0 wt% CNTs content was 496.1 HV, which was about 13.89% higher than that of the matrix alloy. With the increase of adding CNTs content, the oxidation mass gain first decreased and then increased. The oxidation mass gain of composites with adding 1.0 wt% CNTs content was 2.212 mg cm〈sup〉−2〈/sup〉, which was about 63.33% less than that of the matrix alloy, and the parabolic rate constant (〈em〉k〈/em〉〈sub〉p〈/sub〉) was the minimum, which was 1.67 × 10〈sup〉−3〈/sup〉 mg〈sup〉2〈/sup〉 cm〈sup〉−4〈/sup〉 h〈sup〉−1〈/sup〉. The oxidation resistance of the composites was better than the matrix alloy.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The superhydrophobic fluorosilicone/silica (FS/SiO〈sub〉2〈/sub〉) hybrid composite coating was easily fabricated by one-step blending method in this study, whose durable superhydrophobicity could be ensured by fluorosilicone resin (FS) matrix and perfluorine-SiO〈sub〉2〈/sub〉 nanoparticles. The prepared perfluorine-SiO〈sub〉2〈/sub〉 nanoparticles were detected using FESEM and FT-IR spectra, and the wettability and dispersion effects were studied. The surface morphologies and hydrophobicity of FS/SiO〈sub〉2〈/sub〉 coating on glass plates were investigated by AFM and optical contact angle meter, while the adhesion, wear-resistance and chemical regent-resistance for FS/SiO〈sub〉2〈/sub〉 superhydrophobic coating were also discussed. At last, the self-cleaning and anti-icing performances of prepared FS/SiO〈sub〉2〈/sub〉 superhydrophobic coating were explored. It could be found that the FS coating doped with more than 22% SiO〈sub〉2〈/sub〉 would exhibit superhydrophobicity. The water contact angle of the superhydrophobic FS coating could reach 161° and sliding angle 2° in the best condition. The superhydrophobic FS/SiO〈sub〉2〈/sub〉 coating possesses relatively satisfied mechanical and chemical stability. Moreover, the prepared superhydrophobic FS/SiO〈sub〉2〈/sub〉 hybrid composite coating provided an available selection of protecting surfaces against contamination and icing which validated the practicability.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉We studied the low-field microwave absorption (LFMA) in polycrystalline pellet and powdered (0.1–0.2 µm particle size) samples with a nominal composition of Zn〈sub〉1 − 〈em〉x〈/em〉〈/sub〉(Mn:Fe(Ni))〈sub〉〈em〉x〈/em〉〈/sub〉O (〈em〉x〈/em〉 = 0.02). LFMA signals are stronger in the case of Mn:Fe co-doped ZnO, as compared to that of Mn:Ni co-doped ZnO. While the bulk samples show hysteresis, it disappears in the case of powdered samples. Further the line shapes of LFMA were modified with powdering, leading to small saturation fields for LFMA. This indicates that the microwave absorption in these powders is more sensitive than in the pellet form. We interpret these results in terms of interparticle–interfacial pinning. In this work, we clearly establish the low-field tunability of microwave absorption in the Zn〈sub〉1 − 〈em〉x〈/em〉〈/sub〉(Mn:Fe(Ni))〈sub〉〈em〉x〈/em〉〈/sub〉O (〈em〉x〈/em〉 = 0.02) system, which is good for the applications as microwave absorbers with small field tunability as a functionality. This means LFMA can give inputs for the right choice of material for field-tunable microwave absorber design.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The spherification method was adapted to macroporous tetragonal polycrystalline zirconia ceramic fabrication from baddeleyite. Dependences of the material microstructure, its porosity, phase composition and mechanical properties on the sintering temperature were investigated. The opportunity for controlling the porosity and mechanical properties of produced spherical macroporous zirconia ceramic via the sintering temperature variation was revealed. Beads sintered at 1100 °С are characterized by the optimal combination of porosity, hardness, Young’s modulus and breaking force.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Thin films of Tb-doped CdO were grown on FTO substrates using the sol–gel-spin coater technique. XRD studies confirmed the polycrystalline cubic growth of the films with a (200) preferential orientation. XRD analysis was used to estimate the crystallite sizes, dislocation density, and microstrain values, and found that they are highly dependent on the doping percentage. Homogeneous distributions of the nano-gains were observed from the AFM studies. Energy-dispersive spectroscopy and mapping analyses were used for the uniform elemental composition confirmation. All the films displayed high transmission reaching nearly 80% in the visible spectrum and the effect of Tb doping was very clear by corresponding systematic increase in intensities. The direct band-gap values were estimated from the Tauc plots and are found to be highly tunable based on the doping percentage, which was varying between 2.79 and 2.91 eV. The refractive index and extinction coefficient values are lies between 1.8 and 2.5 and 0.44 to 0.82. The 〈span〉 〈span〉\({\chi ^{(1)}}\)〈/span〉 〈/span〉 values are found to be varying between of 0.05 to 0.45 within the range 1–4 eV. This suggests all the linear and nonlinear optical properties of the present samples can be tailored for the various applications by the doping.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, a continuum theory for describing the magnetostrictive behavior of magnetic nanofilms is proposed. Surface effects (including surface elastic and surface magnetoelastic effects) as well as symmetry lowering of nanofilms are considered in the theoretical scheme. The spherical symmetry is lowered to the cylindrical one in nearly two-dimensional nanofilms. And then, there are some additional new elastic and magnetoelastic parameters induced by symmetry lowering have to be reckoned into model the magnetostriction of nanofilms rigorously. The application of our theoretical scheme to Fe nanofilms shows good agreement with experiment. The magnetostriction minimum vs film thickness of Fe nanofilms was produced straightforwardly. In addition, the surface elastic and surface magnetoelastic constants are physically reasonable and consistent with most solid surfaces (on the order of 1–10 J/m〈sup〉− 2〈/sup〉 for surface elasticity and 10〈sup〉− 2〈/sup〉–10〈sup〉− 4〈/sup〉 J/m〈sup〉− 2〈/sup〉 for surface magnetoelasticity). This fact confirms the great importance of additional new elastic and magnetoelastic parameters in magnetostriction theory of magnetic nanofilms. The relationship (〈em〉λ〈/em〉〈sub〉x〈/sub〉 = − 2〈em〉λ〈/em〉〈sub〉y〈/sub〉 = − 2〈em〉λ〈/em〉〈sub〉z〈/sub〉) between magnetostrictions breaks down for nanofilms. In addition, when the magnetic field is applied along vertical direction, the magnetostriction of nanofilms behaves different from the case that magnetic field is applied along in-plane direction.〈/p〉

Description: 〈p〉The author of the original version of this article makes the following corrections:〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Porous mullites used as ceramic membranes were fabricated and coated with TiO〈sub〉2〈/sub〉 and 0.1 wt% Cu(II)-grafted TiO〈sub〉2〈/sub〉 powders. A spinning coating technique was applied for the coating process. Antibacterial activities of the coated mullites were tested against pathogenic bacteria 〈em〉Escherichia coli〈/em〉 (〈em〉E. coli〈/em〉) by following the experimental methods of ISO 17094:2014 standardized for testing photocatalyst materials under visible light of a florescent lamp as an indoor-tested condition. Mullites without coatings were used as control samples. After 4 h of light exposure, the number of the initially viable bacteria increased significantly for the uncoated mullites and decreased for all of the coated mullites. Coating layers of TiO〈sub〉2〈/sub〉 and Cu-grafted TiO〈sub〉2〈/sub〉 could inactivate 〈em〉E. coli〈/em〉 under light illumination. In dark condition, 0.1 wt% Cu(II)-grafted TiO〈sub〉2〈/sub〉 coating on the mullites could inactivate the bacteria, while TiO〈sub〉2〈/sub〉 coating on the mullites could not inactivate the bacteria. The experimental results provide a possibility of using the coated mullites for disinfection applications. Bacterial inactivation mechanisms of TiO〈sub〉2〈/sub〉 and Cu-grafted TiO〈sub〉2〈/sub〉 in coating layers were investigated and discussed in terms of microstructural observation on the coating layers.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Nitrogen doping is often used to expand the response range of wide-bandgap semiconductors to improve their photoelectrical properties. Unique morphology regulatory effect of NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉 ions on one-dimensional TiO〈sub〉2〈/sub〉 nanorod arrays (TNAs) is proved in this research for the first time, but nitrogen-doping effect is hardly detected. Once NH〈sub〉4〈/sub〉Cl is added, the growth of TNAs is greatly promoted especially in radial direction, but little amount of nitrogen from NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉 ions can enter the modified TNAs (N-TNAs). Furthermore, the bandgap energy of N-TNAs is almost unchanged compared with TNAs, meaning that trace nitrogen doping does not affect response ability to irradiation. When fabricated into dye-sensitized solar cells (DSSCs) with N-TNAs, the optimal photoelectrical conversion efficiency (3.16%) is nearly twice that with TNAs (1.62%). It is worth noting that the increased efficiency mainly results from the photoinduced current but not voltage. Second, the change of conversion efficiency is related to nanorod length. In summary, the improvement of photoelectrical property is caused by the directional growth of nanorods, which results from the addition of NH〈sub〉4〈/sub〉〈sup〉+〈/sup〉 ions as an effective structure regulatory agent.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Elastomeric cellular materials with different ordered microstructures are additively manufactured in this work. Via designing the microscale architectures, the cellular materials can distinguish their mechanical behaviors among uniaxial compressive, bending, and combinative deformations. Theoretical models are developed herein, and both calculation and experiment results note that the mechanical behaviors of the cellular materials highly depend on the filament layer height, the spacing, and the diameter. In comparison with traditional elastomeric cellular, the additively manufactured soft samples can finetune their mechanics to meet the different requests and would be beneficial in extensive applications.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, an attractive, ultra-wideband, and polarization-insensitive fractal perfect metamaterial absorber had been proposed based on a tree-shaped microstructure. The absorber was composed of two dielectric substrates, a three-dimensional fractal metal tree, and four lumped resistances. The absorption mechanism and different modes for the absorber had been analyzed in simulation. The characters of polarized-insensitivity and wide-incident absorption for the proposed metamaterial absorber were systematically illuminated by the near electric fields, angular absorptions, and surface current distributions. A presented perfect metamaterial absorber device had been easily implemented using the common printed circuit board method and was measured in a microwave anechoic chamber. The results showed that this proposed FPMA provided a relative bandwidth of 86.9% with the absorptivity larger than 80%. Both the simulated and experimental results adequately verified the characters of wideband, wide-incident, and polarization-insensitive absorption.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Phase transformation characteristics of an aged NiTiHfPd shape memory alloy were investigated through thermal cycling experiments via the differential scanning calorimetry technique. Effects of heating/cooling rate and thermal cycling on the phase transformation temperatures, enthalpies, and thermal hysteresis values were revealed. It was found that phase transformation temperatures and thermal hysteresis values alter considerably with thermal cycling. The transformation temperatures were found to be above 80 °C for all the heating rates, which makes this alloy a promising candidate for high-temperature applications in the selected aging conditions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Nanocrystalline Fe〈sub〉46〈/sub〉Co〈sub〉34〈/sub〉Ni〈sub〉20〈/sub〉 alloy powder was successfully fabricated by mechanical alloying. The alloy powder (mean particle size ~ 5.4 μm and grain size ~ 15 nm) was composed of two phases—the f.c.c. phase and the b.c.c. phase. At 300 K, the saturation magnetization (〈em〉M〈/em〉〈sub〉S〈/sub〉), the remanent magnetization (〈em〉M〈/em〉〈sub〉R〈/sub〉), and the intrinsic coercivity (〈em〉H〈/em〉〈sub〉CI〈/sub〉) of the as-fabricated alloy powder were ~ 169 Am〈sup〉2〈/sup〉kg〈sup〉− 1〈/sup〉, ~ 2 Am〈sup〉2〈/sup〉kg〈sup〉− 1〈/sup〉, and ~ 3.3 kAm〈sup〉− 1〈/sup〉, respectively. The nanocrystalline powder exhibited significantly superior soft-magnetic properties—decrease in 〈em〉H〈/em〉〈sub〉CI〈/sub〉 by ~ 15 times and increase in 〈em〉M〈/em〉〈sub〉S〈/sub〉 by ~ 30%—compared to the nanoparticles of similar compositions synthesized by chemical methods. The 〈em〉M〈/em〉〈sub〉S〈/sub〉, 〈em〉M〈/em〉〈sub〉R〈/sub〉, and 〈em〉H〈/em〉〈sub〉CI〈/sub〉 decreased with an increase in temperature from cryogenic temperatures to ambient temperatures. The alloy powder was relatively stable up to ~ 600 K. The alloy powders thermally treated at 800 K and 900 K exhibited improved soft-magnetic properties compared to the as-fabricated alloy powder—the 〈em〉M〈/em〉〈sub〉S〈/sub〉 increased by ~ 12% and the 〈em〉H〈/em〉〈sub〉CI〈/sub〉 decreased by ~ 30%.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉We investigate the efficacy of polyethylene glycol (PEG) and amine-functionalized MWCNT decorated with MnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanocomposites as heating material for magnetic hyperthermia applications. Samples are prepared by a standard solvothermal method. Phase formation of MnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 has been confirmed by X-ray diffractogram and attachment of nanoparticles on the surface of functionalized MWCNT is evident from transmission electron microscopic image of nanocomposite. Fourier transform infrared spectrum of PEG-functionalized MWCNT and amine-functionalized MWCNT confirmed the presence of PEG and amine group, respectively. As desirable for stability in magnetic hyperthermia, vibration sample magnetometer study suggests superparamagnetic behaviour of all the samples at temperatures 300 K, 200 K and 100 K except at 5 K, which is below blocking temperature as confirmed by ZFC–FC curves. Estimated Curie temperature (〈em〉T〈/em〉〈sub〉C〈/sub〉) and room temperature effective anisotropy is found to increase in nanocomposites, highest for amine-functionalized MWCNT/MnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 nanocomposite. A clear correlation between effective anisotropy and heat generation capability (SAR/ILP) has been observed: higher the anisotropy, higher is the heat generation capability (SAR/ILP).〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉A novel nanocomposite coating, containing calcium titanate (CaTiO〈sub〉3〈/sub〉), sodium titanate nanotube (Na-T) and rutile, was prepared on a titanium substrate. At first, calcium phosphate was deposited electrochemically on Ti substrate. Hydrothermal processing at 130 °C in 10 M NaOH transformed calcium phosphate layer into well-crystallized calcium titanium oxide hydroxide (Kassite) and titanium surface into Na-T. Annealing at 350 °C transformed the titanium metal surface into rutile (TiO〈sub〉2〈/sub〉) and the final coating was CaTiO〈sub〉3〈/sub〉/Na-T/rutile composite. Hydrothermal treatment decreases adhesion bond strength and microhardness. Although the adhesion strength of the final coating was comparative to that of the initial coating, hardness and corrosion resistance were increased with annealing at 350 °C due to the formation of buffer layer of rutile phase.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, we have demonstrated UV photodetector based on SnO〈sub〉2〈/sub〉 nanowire (NW) arrays fabricated using a catalytic free and controlled growth process called glancing angle deposition technique. The fabricated SnO〈sub〉2〈/sub〉 NWs were amorphous in nature with highly periodic and perpendicularly oriented structures of length ~ 160 ± 5 nm with ~ 60 ± 5 nm average diameter. The reported Au/SnO〈sub〉2〈/sub〉 NW/n-Si device showed a good rectifying behavior with a rectification ratio of ~ 6 due to the formation of high-quality Schottky contact at the Au/SnO〈sub〉2〈/sub〉 NW interface. The Au/SnO〈sub〉2〈/sub〉 NW/n-Si device exhibited a high responsivity (0.142 A/W) and external quantum efficiency (56.8%) at − 2 V applied bias as compared to the Au/SnO〈sub〉2〈/sub〉 thin-film (TF)/n-Si device. Moreover, the Au/SnO〈sub〉2〈/sub〉 NW/n-Si device attained a high detectivity of 10.8 × 10〈sup〉10〈/sup〉 Jones and noise equivalent power as low as 38.8 × 10〈sup〉−12〈/sup〉 W. The high surface to volume ratio and the enormous amount of photogenerated carriers in case of SnO〈sub〉2〈/sub〉 NW arrays made the Au/SnO〈sub〉2〈/sub〉 NW/n-Si device to exhibit high photosensitivity. Furthermore, on UV illumination, the Au/SnO〈sub〉2〈/sub〉 NW/n-Si detector showed fast device response with a rise time of 0.18 s and a fall time of 0.25 s. The current conduction mechanism in case of Au/SnO〈sub〉2〈/sub〉 NW/n-Si device is explained with respect to device band diagram.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Cadmium sulfide (CdS) nanoparticles were prepared by hydrothermal method at 150 °C under different reaction times. It was found that hydrothermal method is an effective, quick, and eco-friendly method to synthesis CdS nanoparticles of hexagonal structure at lower temperature. X-ray peak profile analysis by Williamson–Hall analysis and size–strain plot was employed to estimate the crystallite size and lattice strain of the synthesized CdS nanoparticles and to investigate their effects on the peak broadening. The values of strain, stress and energy density were determined for all XRD peaks of wurtzite hexagonal phase of CdS, by applying various forms of Williamson–Hall procedure, such as UDM (uniform deformation model), USDM (uniform stress deformation model) and UDEDM (uniform deformation energy density model). The obtained results indicate that the crystallite size of CdS nanoparticles estimated from Scherrer equation, Williamson–Hall plots and size–strain plot, are nearly similar and in the range of 14–37 nm. CdS nanoparticles were also investigated using high-resolution transmission electron microscopy (HR-TEM), Fourier transform infra-red spectroscopy (FT-IR), and UV–visible and fluorescence spectroscopy. A dependence of the band gap and the nanoparticle size on the reaction time was reported.〈/p〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉A novel hierarchical samarium (Sm)-doped ZnO nanorod–nanosheet architecture with high-temperature ferroelectricity (〈em〉T〈/em〉〈sub〉c〈/sub〉 ~ 110 °C, 〈em〉E〈/em〉〈sub〉c〈/sub〉 ~ 3.64 kV/cm and 〈em〉P〈/em〉〈sub〉r〈/sub〉 ~ 0.08 μC/cm〈sup〉2〈/sup〉) have been developed here using wet chemical co-precipitation method. In this study, we show the origin of ferroelectric behavior in Sm-doped ZnO product and study the effect of frequency and temperature on its dielectric characteristics. Interestingly as an impact of Sm-doping, the morphology of pristine ZnO got evolved from 1D nanopencils (NPCs) to 3D hierarchical architectures composed of both 1D nanorods (NRs) and 2D nanosheets (NSs). Crystallite size (〈em〉L〈/em〉), lattice strain (〈em〉ε〈/em〉), deformation stress (〈em〉σ〈/em〉), and uniform energy density (〈em〉u〈/em〉) of both isolated 1D NPCs and 3D hierarchical NR–NS architectures were evaluated using the Debye–Scherrer and Williamson–Hall methods. Temperature-dependent real dielectric constant (〈em〉ε〈/em〉′) revealed a ferro- to para-electric transition peak at 110 °C. Temperature-dependent complex dielectric constant (〈em〉ε″〈/em〉), dielectric loss (tan 〈em〉δ〈/em〉) and ac conductivity (〈em〉σ〈/em〉) were found to increase with temperature. The frequency-dependent dispersion curves of dielectric properties showed an increase in ac conductivity with increase in frequency whereas complex part of dielectric constant and dielectric loss showed an opposite trend. The Sm-doped ZnO NR–NS architecture exhibits weak ferroelectricity with a coercive field (〈em〉E〈/em〉〈sub〉c〈/sub〉) of 3.64 kV/cm and a remnant polarization (〈em〉P〈/em〉〈sub〉r〈/sub〉) of 0.08 μC/cm〈sup〉2〈/sup〉 at room temperature. Moreover, the high-temperature ferroelectricity established in this work will make Sm–ZnO a futuristic material in the field of designing memory devices.〈/p〉 〈/span〉 〈span〉 〈h3〉Graphical abstract〈/h3〉 〈p〉 〈span〉 〈span〉 〈img alt="" src="https://static-content.springer.com/image/MediaObjects/339_2019_2584_Figa_HTML.png"〉 〈/span〉 〈/span〉 〈/p〉 〈/span〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, MoS〈sub〉2〈/sub〉/PbI〈sub〉2〈/sub〉 heterostructures were synthesized via a two-step synthesis method using vapor deposition and direct water bath heating. Raman spectroscopy and Atomic Force Microscope were used to characterize the MoS〈sub〉2〈/sub〉/PbI〈sub〉2〈/sub〉 heterostructures. The Kelvin probe force microscope was characterized the surface potential of MoS〈sub〉2〈/sub〉/PbI〈sub〉2〈/sub〉 heterostructures. It has shown that the surface potential has undergone a significant change transfer in the interlayer between MoS〈sub〉2〈/sub〉 and PbI〈sub〉2〈/sub〉, which means that at the interface charge transfer occurs and the electrons transfer from MoS〈sub〉2〈/sub〉 to PbI〈sub〉2〈/sub〉. These results provide a theoretical basis for further understanding of the electrical properties of MoS〈sub〉2〈/sub〉/PbI〈sub〉2〈/sub〉 heterostructures.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, the effects of magnetic flux and the width of the quantum ring on plasmon frequency are studied in a narrow quantum ring threaded by magnetic flux. Plasmon frequency is obtained by random phase approximation in the zero wave vector limits. Calculation of plasmon frequency as a function of magnetic flux shows Aharonov–Bohm oscillations. The periodicity and the amplitude of Aharonov–Bohm oscillations depend on magnetic flux and the width of the ring. In other words, the plasmon frequency of the quantum ring is sensitive to the variation of the magnetic flux and when the width is small, the modulation is more sensitive since the period and amplitude are smaller. The absorption coefficient versus ring radius changes from infrared region to ultraviolet region, which it can be of relevant application in solar cells.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉A solid solution of BaMnO〈sub〉3−δ〈/sub〉 and Bi〈sub〉0.5〈/sub〉Na〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 was prepared using a sol–gel method. X-ray diffraction analysis of Bi〈sub〉0.5〈/sub〉Na〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 − 〈em〉x〈/em〉 BaMnO〈sub〉3−δ〈/sub〉 samples indicated a rhombohedral structure of Bi〈sub〉0.5〈/sub〉Na〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 materials during distortion due to the random distribution of Ba and Mn cations in the host lattice. The substitution of Ba and Mn at 〈em〉A〈/em〉- and 〈em〉B〈/em〉-sites in the perovskite structure of Bi〈sub〉0.5〈/sub〉Na〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 changed the optical band gap due to local defect and/or promotion of oxygen vacancies. The samples exhibited strong room temperature ferromagnetism, which overcame the weak ferromagnetism and diamagnetism of Bi〈sub〉0.5〈/sub〉Na〈sub〉0.5〈/sub〉TiO〈sub〉3〈/sub〉 materials. Our study provided a flexible approach to integrate the ferromagnetism properties of ferroelectric materials.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Magnetron co-sputtering method followed by selenization was used for the preparation of Cu〈sub〉2〈/sub〉Zn(Sn,Ge)(S,Se)〈sub〉4〈/sub〉 (CZTGeSSe) thin film. The impact of Ge doping layer with different sputtering times on crystalline quality, surface roughness, band structure and device performance of CZTGeSSe absorber was systematically investigated. It was found that the increased Ge/(Ge + Sn) ratio could effectively promote the grain growth and improve the band mismatching of CZTGeSSe/CdS interface. The CZTGeSSe thin film with minimum roughness and increased CBO (− 0.54 to − 0.41 eV) was obtained with the increased Ge/(Ge + Sn) ratio of 7.3%. However, oversized grain with rougher surface could result in a non-uniform coverage phenomenon of CdS layer, leading to severe interface recombination. After optimizing the Ge/(Ge + Sn) ratio, the best device performance with an efficiency of 3.19% was achieved in flexible CZTGeSSe thin film solar cells.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Transport measurement techniques are generally considered to be indirect methods of probing the phenomenology of materials and hence are limited in scope and require careful interpretation. However, when performed with due care and precision in addition to other characterization methods, magnetotransport measurements are an essential tool in the study of magnetic and electronic materials particularly in proving potential devices that function on the basis of charge or spin transport. In this work, we demonstrate the advantage of employing a method that simultaneously measures the planar Hall effect and the anisotropic magnetoresistance which are two aspects of the resistivity anisotropy to characterize a range of semiconducting and conducting oxide thin films. The development of novel magnetotransport characterization methods is motivated by the need for reliable measurements of the electronic properties of a wide range of materials under varying thermal, mechanical and magnetic conditions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉A novel and simple fabrication method was proposed to produce microfluidic channels with various cross-sectional shapes, such as parallelogram, rhombus, pentagon and hexagon. The present study has the advantages of not only fabricating the microfluidic channel shapes that have not been reported before, but also the fabrication process is simple, flexible and robust. Microfluidic channels were fabricated using anisotropic wet etching of Si wafer and self-alignment between Si structure and PDMS mold. In this regard, (100) single crystal Si wafer was used to fabricate the Si microchannel and the master for PDMS mold using photolithography and anisotropic KOH etching. The Si structure for the microchannel and master were formed from the same Si wafer by KOH etching, and the PDMS mold was made from the Si master. Finally, the microchannels with various cross-sectional shapes could be easily formed through self-alignment of the Si microchannel and PDMS mold. They were permanently bonded using O〈sub〉2〈/sub〉 plasma treatment. It is expected that the fabricated microchannel with various cross-sectional shapes can be used in wide fields such as heat transfer, microscale transport of particle and fluid, and particle separation based on inertial focusing. 〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Transition metal oxide core–shell-nanostructured Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉 is attractive in photocatalytic, optoelectronics and optical applications. Magnetic Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉 core–shell nanocomposites were synthesized by a facile hydrothermal method. Transmission electron microscopy (TEM) results show that the 80-nm-diameter nanoparticles were composed of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 core and MoS〈sub〉2〈/sub〉 shell. The presence of characteristic of Fe–O and Mo–O vibrations in Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉 FT-IR spectra indicate the Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 has been composited with MoS〈sub〉2〈/sub〉 successfully. The optical UV–Vis spectra of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉 composites exhibited a strong peak at 250–300 nm due to the strong absorption of MoS〈sub〉2〈/sub〉. The photoluminescence spectra of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉 showed two peaks at 670 and 625 nm corresponding to A1 and B1 excitons of MoS〈sub〉2〈/sub〉. Glass-containing nanoparticles have promising multifunctional advantages such as the simultaneous existence of magnetic, optical and photoluminescence. Glasses containing different Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉 contents were fabricated in this study by melt-quenching method. Glass network was disordered by the doping, and as the doping content increasing, the coordination numbers were changed and more non-bridging oxygen numbers were produced, these modifications on glass structure induced changes of glass properties. Compared to spectra of base glass, the UV–Vis absorption spectra of doped glasses showed a red-shift in cutoff wavelength and an absorption peak around 680 nm due to the excitation of Mo〈sup〉5+〈/sup〉 (4d〈sup〉1〈/sup〉) ions. The photoluminescence spectra of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉-doped glasses present one intense peak centered around 570 nm due to the charge transfer of O〈sup〉2−〈/sup〉→Mo〈sup〉6+〈/sup〉 ions in MoO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉 units, and the intensity of this emission peak increased with doping contents. The conductivity of base glass gets increased from 1.59 × 10〈sup〉−7〈/sup〉 to 2.08 × 10〈sup〉−6〈/sup〉 S cm〈sup〉−1〈/sup〉 when the doping content reaches to 5%. Such improvement is mainly caused by the non-adiabatic small polaron hopping at 473 K and non-bridging oxygens production. Glass doped with 5% Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉 exhibited promising photoluminescence, optical cutoff wavelength (526 nm) and high electrical conductivity (2.08 × 10〈sup〉−6〈/sup〉 S cm〈sup〉−1〈/sup〉) due to the charge transfer of Fe and Mo ions and high polarization property of Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉@MoS〈sub〉2〈/sub〉.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Flexoelectricity offers a number of advantages in micro/nano-scale devices when compared with piezoelectricity as confirmed through numerous experiments and theoretical analyses. Snap-through behavior in bistable plate would convey a higher conversion efficiency for energy harvesting. However, there is no theoretical research on micro/nano-scale energy harvester with flexoelectricity based on bistable plate. This paper describes an electro-thermo-mechanical coupling system of micro/nano-scale bistable plates for piezoelectric energy-harvesting applications. The nonlinear geometric theory of Von Kármán, strain gradient theory, the flexoelectric effect, and Hamilton’s principle were used to derive nonlinear dynamic formulas. The ambient vibration frequency and snap-through behavior both have an effect on the output voltages calculated by Matlab® software. An expression for the energy conversion efficiency of the bistable plate was derived and the influence of resistance on this efficiency was investigated. The result showed that the snap-through behavior delivered a large-amplitude vibration and a higher output voltage at the range of one-third super-harmonic resonance (2.8–3.5 MHz) for the micro/nano-scale bistable plate. This work will be helpful in the design of micro/nano-scale bistable plates with higher output voltages and improved conversion efficiencies for energy harvesting.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Due to the great interest in obtaining solar cells based on graphene/semiconductor Schottky junction and MoS〈sub〉2〈/sub〉/semiconductor heterojunction, in this review, we are presenting the technical details regarding those solar cells. For a better understanding of the technology used in the solar cells mentioned above, we initially show the graphene/semiconductor Schottky junctions and the adaptation of the thermionic theory to this type of junction. After this, we show the graphene/semiconductor Schottky junction solar cells and the MoS〈sub〉2〈/sub〉/semiconductor heterojunction solar cells. It is noteworthy that the understanding of this technology will serve as the basis for studies of more complex nanophotonic solar cells.〈/p〉

Description: 〈p〉In the original publication of this article the author noticed some important corrections.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, we perform an integration between the tape casting and magnetron sputtering techniques to produce hybrid materials. To this end, trilayered nanostructures of NiFe/Cr/NiFe based on 〈span〉 〈span〉\(\hbox{Al}_{2}\hbox{O}_{3}\)〈/span〉 〈/span〉 flexible sheet are produced by magnetron sputtering deposition. From the well-known dependence of the magnetic properties of NiFe alloy as a function of the thicknesses, here we study samples where the NiFe thicknesses are varied from 105.0 nm up to 142.5 nm, while the Cr layers varied from 15.0 nm up to 90.0 nm. From the structural characterization, a polycrystalline behavior for the 〈span〉 〈span〉\(\hbox{Al}_{2}\hbox{O}_{3}\)〈/span〉 〈/span〉 grains dispersed in an amorphous matrix and a (111) orientation for the NiFe layers are observed. The magnetic characterization reveals the mirroring of the studied trilayered nanostructures concerning the traditional studies for the same thicknesses grown onto rigid (glass) substrate. These results bring these hybrid nanostructures as an attractive candidate for a flexible non-magnetostrictive material to use in smart and nano-functionalized ceramic materials.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉LaBMoO〈sub〉6〈/sub〉:Dy〈sup〉3+〈/sup〉 phosphor is successfully synthesized in the air by the solid-state reaction method. The luminescence properties and crystal structures are researched. LaBMoO〈sub〉6〈/sub〉:Dy〈sup〉3+〈/sup〉 phosphor with excitation at 388, 398, 426, and 451 nm emits yellow light. The emission spectrum of LaBMoO〈sub〉6〈/sub〉:Dy〈sup〉3+〈/sup〉 phosphor in the range of 450–780 nm contains four emission bands peaking at ~ 480, 570, 658, and 750 nm because of the 〈sup〉4〈/sup〉F〈sub〉9/2〈/sub〉 → 〈sup〉6〈/sup〉H〈sub〉15/2〈/sub〉, 〈sup〉6〈/sup〉H〈sub〉13/2〈/sub〉, 〈sup〉6〈/sup〉H〈sub〉11/2〈/sub〉, and 〈sup〉6〈/sup〉H〈sub〉9/2〈/sub〉 transitions of Dy〈sup〉3+〈/sup〉 ion, respectively. The optimal Dy〈sup〉3+〈/sup〉 ion concentration is ~ 6 mol% in LaBMoO〈sub〉6〈/sub〉:Dy〈sup〉3+〈/sup〉 phosphor. The lifetime of LaBMoO〈sub〉6〈/sub〉:Dy〈sup〉3+〈/sup〉 phosphor decreases from 0.467 to 0.279 ms with increasing Dy〈sup〉3+〈/sup〉 ion concentration from 2 to 10 mol%. The energy-level diagram of Dy〈sup〉3+〈/sup〉 ion is used to explain the luminous mechanism of LaBMoO〈sub〉6〈/sub〉:Dy〈sup〉3+〈/sup〉 phosphor. The experimental results indicate a potential application of LaBMoO〈sub〉6〈/sub〉:Dy〈sup〉3+〈/sup〉 phosphor as yellow phosphor for light-emitting diode based on near ultraviolet and blue chips.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉High quality, ~ 120 nm thin ZnO and Ti-doped ZnO (TZO) films were deposited on silicon substrates using magnetron co-sputtering technique. Surface roughness of the films was ~ 2 nm. Ti incorporation effect on the structure, morphology, conductivity, density of states (DOS) and conduction mechanism was investigated in detail. Ti ions were incorporated in the interstitial sites of hexagonal ZnO lattice. Average crystallite size increased from ~ 16.63 to ~ 19.08 nm upon Ti doping in ZnO film. Conduction mechanism changed from overlapping large polaron tunneling (OLPT) for undoped ZnO film to corelated barrier hopping (CBH) for TZO film. The experimental data were fitted theoretically using OLPT and CBH models to calculate frequency and temperature-dependent DOS. An enhancement of ac conductivity and DOS was observed with the doping of Ti in ZnO thin film. Complex modulus study of TZO film revealed transition from long-range mobility to short-range mobility with increase in frequency.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The ZnFe〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 and ZnLa〈sub〉0.5〈/sub〉Fe〈sub〉1.5〈/sub〉O〈sub〉4〈/sub〉 zinc ferrites had been prepared by the hydrothermal method. The detection method using in this investigation was X-ray diffraction, scanning electronic microscope, Fourier transformed infrared spectrometer (FTIR), and vibrating sample magnetometer. The results indicated that the samples had spinel structures. This study revealed that the crystallite size, lattice constant, and X-ray density of samples were decreased, while prolonged holding time and increased temperature, whereas the crystallite size was increased with the temperature increasing. Four absorption bands were observed in FTIR spectra and assigned to the corresponding site bonds. The saturation magnetization (〈em〉M〈/em〉〈sub〉S〈/sub〉), coercivity, magnetic moment, and anisotropy constant (〈em〉K〈/em〉) were affected by the holding time and temperature. Anisotropy constant proved dependence on the temperature, and it increased with the enhancement of temperature.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉We report on the effects of interactions on the magnetocaloric properties of γ-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles with an average fixed size of 4.7 nm. The influence of particles interaction was investigated by changing their surrounding through the dispersion of γ-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles in polyvinyl alcohol with different concentrations: powder, IN (isolated particle near) and IF (isolated particle far). 〈em〉T〈/em〉〈sub〉B〈/sub〉 decreases from 124 to 21 K with increasing volume fraction of γ-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 nanoparticles in polyvinyl alcohol from powder to IF sample, due to decrease in the magnetic interparticle interactions (dipolar interaction). The temperature dependence of the magnetic entropy change (− Δ〈em〉S〈/em〉〈sub〉M〈/sub〉) was determined using isothermal magnetization. The caret shape of (− Δ〈em〉S〈/em〉〈sub〉M〈/sub〉) curves shows that the magnetic transition near 〈em〉T〈/em〉〈sub〉B〈/sub〉 for all samples was a second-order phase transition. Under a magnetic field change of 10 kOe, the (− Δ〈em〉S〈/em〉〈sub〉M〈/sub〉) and relative cooling power (RCP) decrease from 1.11 to 0.65 J/kg K and 64–23 J/kg when passing from powder to IF samples, respectively. The decrease in the magnetocaloric performance with decreasing the magnetic interparticle interactions was attributed to the decrease of magnetization.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Tungsten trioxide was prepared by a hydrothermal method, and WO〈sub〉3〈/sub〉/g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 composite photocatalysts were prepared in two steps by hydrothermal synthesis and muffle furnace calcination. The hydrogen production experiment was carried out using g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 and WO〈sub〉3〈/sub〉/g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 composites under simulated visible light irradiation. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), ultraviolet–visible diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FT-IR) and Brunauer–Emmett–Teller (BET) analysis. It was found that WO〈sub〉3〈/sub〉(H〈sub〉2〈/sub〉O)〈sub〉0.333〈/sub〉 prepared by hydrothermal treatment is nanorod-like and forms an effective combination with lamellar g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉. The hydrogen production rate of the optimal sample is 224.4 μmol/h, which is twice that of pure g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉. The addition of tungsten trioxide improves the separation efficiency of photogenerated electron–hole pairs and contributes to the improvement in the photocatalytic performance. This is of great significance to the application of modified g-C〈sub〉3〈/sub〉N〈sub〉4〈/sub〉.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In the present work, Ni〈sup〉2+〈/sup〉 and Cu〈sup〉2+〈/sup〉 ions are doped with TiO〈sub〉2〈/sub〉 using sol–gel technique. The effects of Ni and Cu doping in TiO〈sub〉2〈/sub〉 matrix are characterized by XRD, Micro-Raman, FTIR, UV–DRS, PL, and FESEM with EDS. Furthermore, it is analyzed for photocatalytic activity and magnetic applications. From XRD analysis, it is observed that the peaks corresponding to the planes match with the JCPDS data [anatase: 89-4203] of TiO〈sub〉2〈/sub〉. The crystallite size of the doped samples is found to be greater than that of TiO〈sub〉2〈/sub〉. Micro-Raman analysis shows the confirmation of anatase phase of TiO〈sub〉2〈/sub〉. FTIR analysis confirms the presence of functional groups which are presented in the prepared samples. From UV–DRS, the band-gap values of TiO〈sub〉2〈/sub〉 and doped TiO〈sub〉2〈/sub〉 (Ni〈sup〉2+〈/sup〉, Cu〈sup〉2+〈/sup〉) are found to be 3.25, 2.48, and 1.25 eV. Photoluminescence (PL) results show an emission edge of Ni- and Cu-doped TiO〈sub〉2〈/sub〉 is red shifted which is due to the vacancies of titanium and oxygen imported subsequently during doping. The surface morphology and the elemental composition of Ni- and Cu-doped TiO〈sub〉2〈/sub〉 nanoparticles are also analyzed. The photocatalytic activity of all the prepared samples are assessed by methylene blue dye as testing pollutant and visible radiation. The test reveals that Cu–TiO〈sub〉2〈/sub〉, Ni–TiO〈sub〉2〈/sub〉, and TiO〈sub〉2〈/sub〉 show the degradation efficiency of 68.14, 61.04, and 33.32%, thereby showing that the doped TiO〈sub〉2〈/sub〉 are more efficient in degrading the pollutant and can be applied for future photocatalytic applications. From VSM analysis, the saturation magnetization of Ni–TiO〈sub〉2〈/sub〉 and Cu–TiO〈sub〉2〈/sub〉 is found to be weak and can be improved by the synthesis process and the proportion of dopant.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, we shall show first that both reflection and transmission can be significantly amplified when a beam of electromagnetic wave is normally incident into an active (even lossy) metamaterial slab with near-zero-real-part-of-impedance, which is attributed to effect of interference between forward and backward waves in the slab. Then we demonstrate that extended steady electromagnetic waves can be achieved using a double-slab structure, which may be applied to generate coherent electromagnetic wave with very narrow frequency band and very low divergence angle. This work provides feasible scheme to construct a new type of source of coherent electromagnetic radiation based on new physical mechanism.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉We dealt with the synthesis and photoluminescence (PL) behaviors of the Sm〈sup〉3+〈/sup〉-activated CaLa〈sub〉2〈/sub〉(MoO〈sub〉4〈/sub〉)〈sub〉4〈/sub〉 phosphors. Under 404 nm irradiation, the prepared samples emitted the visible red emissions from the intra-4f transitions of Sm〈sup〉3+〈/sup〉 ions. The color coordinate and color purity of the achieved red emissions were (0.629, 0.370) and 78.2%, respectively. The PL-emission intensity was revealed to dependent on the dopant concentration and the optimal value was 3 mol%. By means of the theoretical calculation, it was found that the involved concentration quenching mechanism was dominated by the dipole–dipole interaction and the critical distance was 40.69 Å. Furthermore, the thermal quenching performance of the resultant phosphors was examined utilizing the temperature-dependent PL-emission spectra and the activation energy was decided to be 0.122 eV. Ultimately, through integrating the synthesized phosphors with a commercial near-ultraviolet chip, a red-emitting light-emitting diode was packaged to explore the feasibility of the Sm〈sup〉3+〈/sup〉-activated CaLa〈sub〉2〈/sub〉(MoO〈sub〉4〈/sub〉)〈sub〉4〈/sub〉 phosphors for solid-state lighting applications.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Nanoparticles of Al〈sub〉0.1〈/sub〉Fe〈sub〉2.9〈/sub〉O〈sub〉4〈/sub〉 (AFO) were synthesized using a simple cathodic electrochemical deposition technique. Structural, morphological, and magnetic properties of AFO were systematically studied. The X-ray powder diffraction analysis indicated the formation of a sample in a single-phase cubic spinel structure. Morphological data analysis of the specimen showed that the AFO sample has a nanoparticle structure with an average diameter of ~ 8 nm. The magnetization measurement as a function of the magnetic field at room temperature confirmed the existence of a superparamagnetic behavior. Additionally, frequency dependence of AC susceptibility analysis indicated a weak interaction between AFO magnetic nanoparticles.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, two-dimensional electron gas (2DEG) mobility analysis of AlN/GaN and InAlN/GaN structures with ultrathin barrier layers by metal organic chemical vapor deposition (MOCVD) has been performed with Hall effect measurements which is carried out under temperature from 15 to 350 K and a single magnetic field of 0.5 T. As a result of the scattering analysis made with Matthiessen’s rule, it is shown that while the interface roughness scattering mechanism is dominated on the 2DEG mobility at low temperatures, the 2DEG mobility has been dominated by the polar optical phonon-scattering mechanism at high temperatures. Also, the acoustic phonon-scattering mechanism is effective on the 2DEG mobility at middle temperature. Furthermore, the interface and the quantum well parameters such as deformation potential, quantum well width, and correlation length of the interface are determined for each. As well as experimental measurements, the conduction band energy diagrams of the studied samples have been calculated using one-dimensional (1D) self-consistent Schrödinger–Poisson equations. A 2D quasitriangular quantum well formation has been shown for each studied samples. 2DEG probability density of samples has been investigated.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉NiO nanoparticles with different sizes were synthesized at different temperatures from 300 to 〈span〉 〈span〉\(700\,^{\circ }\)〈/span〉 〈/span〉C to the study of behavior related to size. The nanoparticles show dimensions in the range 5.07–68.29 nm, which were determined by transmission electron microscopy images. The nanoparticles present an irregular morphology from 300 to 〈span〉 〈span〉\(600\,^{\circ }\)〈/span〉 〈/span〉C, while the observed structure is a truncated octahedron with FCC structure only for samples at 〈span〉 〈span〉\(700\,^{\circ }\)〈/span〉 〈/span〉C. X-ray diffraction measurements and Rietveld analysis verify this crystal structure, the crystal size, and the lattice parameters. Raman spectroscopy of the nanoparticles shows the normal modes of proposed truncated octahedrons related to longitudinal optical, transverse optical phonons, and a combination of both. Optical properties were measured by UV–visible spectroscopy to analyze the variation of the band gap in function of the size. In addition, magnetic measurements, magnetization versus temperature, and magnetization versus magnetic field present ferromagnetic behavior. M–H hysteresis curves show the coercive field with anisotropic characteristics that we related to the competition between two magnetic orders coexisting in the samples.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉CdS thin films doped and co-doped with Fe and Mn were prepared by spray pyrolysis technique and the films were portrayed by X〈strong〉-〈/strong〉ray diffraction, laser Raman, XPS, FESEM with EDAX, UV–Vis, PL, and VSM analyses. The structural parameters were identified and the crystalline nature of the films was confirmed by X-ray diffraction patterns. The different optical phonon modes of vibrations present in the films were studied using laser Raman analysis. XPS analysis was used to study the binding states of electrons at various energy levels and the binding energy shift due to doping in the thin films under study was also determined. The morphology of the thin films was studied using FESEM technique and the change in the morphologies due to doping is evident from the images. To resolve the band gap of the material of the thin films before and after doping, UV–Vis absorption spectra have been recorded using UV–Vis spectrophotometer. It is found that the band gap has been tuned due to doping. PL spectral studies and VSM studies have been employed to study the luminescence and magnetic properties, respectively, with respect to the doping elements. The presence of weak ferromagnetic nature of the doped films indicates that the defects created by the doped elements induced ferromagnetic property even in the CdS thin film.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Sr〈sup〉2+〈/sup〉-doped γ-Ce〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 red pigment was prepared via the combination of coprecipitation and sulfurization process. The effects of the Sr〈sup〉2+〈/sup〉/Ce〈sup〉3+〈/sup〉 mole ratio, 〈em〉x〈/em〉, on the synthesis of γ-Ce〈sub〉2〈/sub〉S〈sub〉3〈/sub〉, crystal structure, color performance, and temperature stability were systematically studied. The results show that a pure γ-Ce〈sub〉2〈/sub〉S〈sub〉3〈/sub〉 can be obtained at 900 °C for 150 min with a Sr〈sup〉2+〈/sup〉 dopant. As the Sr〈sup〉2+〈/sup〉/Ce〈sup〉3+〈/sup〉 mole ratio, 〈em〉x〈/em〉, increases, the band gap of the samples gradually increases and the chromaticity of the samples gradually shifts from red to orange. When the mole ratio, 〈em〉x〈/em〉, is 0.15, the pigment sample has the highest quality red color: 〈em〉L〈/em〉* = 33.14, 〈em〉a〈/em〉* = 33.42, 〈em〉b〈/em〉* = 22.16. The pigment with this composition remains in γ phase when heated at 350 °C for 30 min in air, and maintains an excellent red color: 〈em〉L〈/em〉* = 32.65, 〈em〉a〈/em〉* = 30.35, 〈em〉b〈/em〉* = 19.23.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, we have investigated the performance of solid-state dye-sensitized solar cells (SDSSCs) fabricated from four different hole transport materials (HTMs) through SCAPS-1D simulation. Two organic and two inorganic HTM layers are examined in this study. The structure of SDSSC employed in this work is composed of FTO/TiO〈sub〉2〈/sub〉/N719/HTM/Au and only the HTM layer is changed for each simulation. The materials employed as HTM are PEDOT:PSS, Spiro-OMETAD, CuI, and CuSCN. In each case, the 〈em〉V〈/em〉〈sub〉OC〈/sub〉, 〈em〉J〈/em〉〈sub〉SC〈/sub〉, FF, PCE, and quantum efficiency parameters are analyzed. The effects of HTM type and thickness, temperature and hole concentration on different parameters of the SDSSCs are compared with each other. The results indicate that using CuI as HTM yields better performance in comparison with other HTMs and can reach an efficiency of 17.72%. The simulation results can be used to make a comparison between organic and inorganic HTMs and also to improve the parameters of conductive polymers with secondary doping and to fabricate optimized SDSSCs in laboratory and industrial scales.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉A series of barium, lead borate (BaLB) glasses with chemical composition 〈em〉x〈/em〉 ZnO–(30-〈em〉x〈/em〉) BaO–30PbO–40B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, 〈em〉x〈/em〉 variety 0 ≤ 〈em〉x〈/em〉 ≤ 20 mol % has been prepared and synthesized by a conventional melting method. The structural analysis has been performed using FT-IR techniques. FT-IR confirmed that BO〈sub〉3〈/sub〉, BO〈sub〉4〈/sub〉, PbO〈sub〉6〈/sub〉, and ZnO〈sub〉4〈/sub〉 are structural units. The optical absorption spectra have been studied before and after gamma irradiation. The radiation shielding parameters were evaluated experimentally and theoretically using the XCOM program within the energy range 0.662 MeV–1.333 MeV. In addition, the shielding parameter values investigated using XCOM software are in a good agreement with experimental results. These parameters indicate that the prepared samples possess better shielding properties than ordinary concrete.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Due to the significance of circular-polarized antennas for satellite communications applications, a planar circular-polarized reflector antenna is proposed in this paper, which consists of a circular polarization beam focusing metasurface and a feed helical antenna. The metasurface is realized using circular polarization conversion resonators with deep sub-wavelength size which is based on Pancharatnam–Berry phase. As an example, a Ka-band 150 × 150 mm〈sup〉2〈/sup〉 planar circular-polarized antenna is designed, fabricated and measured with focal length of 150 mm. Both the simulated and measured results agree well and verify that the designed antenna works over 30–34 GHz with gain larger than 20 dB, half-power band width (HPBW) about 4° and axis ratio lower than 3 dB.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this work, Cu〈sup〉+2〈/sup〉-doped ZnS semiconductor nanoparticles have been synthesized using co-precipitation route caped with various surfactants such as diethyl-amine (DEA), poly-vinyl alcohol (PVA), cetyl trimethylammonium bromide (CTAB), polyethylene glycol (PEG) and triethyl-amine (TEA). The structural analysis has been carried out by X-ray diffractometer (XRD) and Fourier-transform infrared spectroscopy (FTIR). Morphological and elemental analysis have been performed by scanning electron microscopy (SEM) and X-ray-dispersive X-ray spectroscopy (EDX), respectively. XRD and FTIR have revealed the cubic structure of prepared nanoparticles. The crystallite size has been calculated in the range 15–20 nm through XRD. A hexagonal peak of ZnO is also observed in XRD pattern. The optical and electrical properties have been studied through UV–Vis spectroscopy and Four-point probe technique, respectively. EDX has revealed the presence of S, Cu and Zn as major elements in prepared samples. Optical band gap energy has been estimated in the range 3.6–4.2 eV with absorption edge from 270 to 277 nm. The conductivity of prepared samples has been increased with the decrease in band gap.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉With an increase in electromagnetic interference pollution, composites for electromagnetic interference shielding (EMIS) with good shielding performance and friendly processability are widely demanded. Herein, a methodology for preparing composites with controllable shielding effectiveness (SE) is proposed. Carbon fiber (CF)-reinforced polylactic acid composites were fabricated by a 3D printing process, and the SE of the composites was controlled by varying the process parameters. To systematically investigate the feasibility of the methodology, the shielding properties, processability, and mechanical properties of the composites were investigated. The results showed that the SE was controlled in the ranges of 25.1–69.9 dB, 51.1–75.6 dB, and 6.8–78.9 dB by tailoring the number of layers (2–12), hatch spacing (1.6–0.8 mm), and filling angle (90°–0°), respectively. The critical mechanism of the controllability is that the content, spatial distribution, and orientation of CFs can be facilely and digitally controlled during processing. A conformal shell with a SE of 38.5 dB was fabricated to demonstrate superior processability of a complex geometry. The maximum tensile and flexural strengths of the composites were 111.0 and 152.9 MPa, respectively, which were much larger than those of most engineering plastics. Using this methodology, an appropriate SE that is neither excessive nor deficient can be readily realized, which helps to maintain high resource utilization. Complex geometries for EMIS can be rapidly and cheaply obtained without molds, which is difficult for traditional processes. These advantages make the 3D-printed CF-reinforced composites competitive with other EMIS materials and traditional processes.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, two synthesis methods of binary compounds of WO〈sub〉3〈/sub〉–TeO〈sub〉2〈/sub〉 with different precursors solutions including HNO〈sub〉3〈/sub〉 (solution A) and HCl (solution B) have been presented. The effect of nitric acid and hydrochloric acid precursors on the structural and optical properties of WO〈sub〉3〈/sub〉–TeO〈sub〉2〈/sub〉 compounds have been studied. The results of X-ray diffraction showed that in the solution containing HNO〈sub〉3〈/sub〉, a large percentage of TeO〈sub〉2〈/sub〉 was transformed to Te during the reaction and for solution containing HCl, the two phases of WO〈sub〉3〈/sub〉 and TeO〈sub〉2〈/sub〉 are observed. The size of the WO〈sub〉3〈/sub〉–TeO〈sub〉2〈/sub〉 nanoparticles synthesized with the precursor B is smaller than the other one. The images of the field emission scanning electron microscope (FE–SEM) for solution containing HNO〈sub〉3〈/sub〉 showed that the morphology of the produced nanoparticles is hexagonal and tetragonal, while solution containing HCl is uniformly polygon monoclinic structure in form of rod. The results of the FT–IR and UV–Vis spectrometry showed that the bonding structure of nanoparticles in solution containing HNO〈sub〉3〈/sub〉 is influenced by environmental factors and affects almost on all the vibrational modes of the WO〈sub〉3〈/sub〉–TeO〈sub〉2〈/sub〉 composition. The energy gap (〈em〉E〈/em〉〈sub〉g〈/sub〉) for the synthesized samples with the processors A and B were obtained 3.65 eV and 4.02 eV, respectively.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This work focuses on the preparation and description of zinc oxide nanoparticles (ZnONPs) by hydrothermal method. The ZnONPs here were used as scattering center after mixture with R6G at concentration 10〈sup〉−4〈/sup〉 mol/l which was doped by PMMA polymer as a film. The UV–visible (UV–Vis) spectroscopy, photoluminescence spectroscopy (PL), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-rays (EDS) spectroscopy, and transmission electron microscopy (TEM) were performed to characterize the growth, morphology, and optical nature of the samples. Practical results indicate a pure growth of ZnO in the solid case by hydrothermal manufacture technique that can produce high crystallinity and a perfect hexagonal quartzite structure. The average particle sizes were measured to range from 10 to 140 nm. The PL spectrum for pure ZnO as powder appears as maximum peak intensity of ultraviolet region at 385 nm and blue emission band around 472 nm at room temperature (RT), while it is observed that sharp peaks with a linewidth of ~ 10 nm emerge from the emission spectra for the sample at ~ 16 mJ pump energy. It is observed that the peak emission wavelength of the dye ZnONP-doped PMMA as a host (~ 569 nm) is different from that of the bare ZnO nanospheres (~ 385 nm).〈/p〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉This paper presents a dynamic model to study triboelectric charge accumulation in a variable capacitive structure with metal–dielectric interface. The presented model addresses a serious flaw of current published theoretical works related to modeling of triboelectric energy harvesters. Electrostatic analysis of the device in the contact and non-contact modes is performed. Based on the analysis of the non-contact mode, a novel technique is introduced to measure stable parasitic triboelectric charge density on the surface of the dielectric layer. Theoretical analysis for positive and negative charge accumulation is performed separately and key characteristic equations of both cases are extracted. A new measurement technique is developed to assess triboelectric charge build-up on the surface of the dielectric layer by employing a simple bridge rectifier as a test circuit. Based on the measured data, a time-dependent exponential model is suggested for triboelectric charge accumulation on the surface of the dielectric layer. The presented dynamic model is a vital asset in modeling dynamic output of triboelectric nanogenerators (TENG’s). The results show that failure to consider triboelectric charge dynamics in modeling of TENG’s would result in more than 50% error in the simulated output characteristics.〈/p〉 〈/span〉 〈span〉 〈h3〉Graphical abstract〈/h3〉 〈p〉 〈em〉Charge accumulation〈/em〉 A new surface charge evaluation technique is introduced. Triboelectric charge accumulation on the surface of dielectrics is calculated and modeled using a simple half-wave rectifier. To get to the model, discrete charge-time points are measured. The dynamic charge model presents an essential asset in simulation of the output performance of TENG’s. positive and negative charge build up is measured.〈span〉 〈span〉 〈img alt="" src="https://static-content.springer.com/image/MediaObjects/339_2019_2495_Figa_HTML.png"〉 〈/span〉 〈/span〉 〈/p〉 〈/span〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Laser-induced periodic surface structures (LIPSS, ripples) have attracted great attentions in the fields of surfaces and interfaces, yet their origin still remains puzzling, especially for dielectrics. In this study, a comparative study of the formation of two distinct classes of ripples on fused silica is provided by carefully adjusting the key parameters of laser fluence and pulse number. Two different ablation regimes are identified for LIPSS formation. The threshold fluence of 〈em〉F〈/em〉 = 4.07 J/cm〈sup〉2〈/sup〉 is defined for the transition from high spatial frequency LIPSS to low spatial frequency LIPSS, which is independent of pulse number. Pulse-to-pulse results show the unique formation processes for each class of LIPSS in different fluence regimes. In the fluence range below the transition threshold (2.54 J/cm〈sup〉2〈/sup〉 〈 〈em〉F〈/em〉 〈 4.07 J/cm〈sup〉2〈/sup〉), the formation of high spatial frequency LIPSS starts from randomly distributed nanogrooves perpendicularly orientated to 〈em〉E〈/em〉, indicating the excitation of surface-plasmon polaritons as a primary formation mechanism. In the higher fluence regime (〈em〉F〈/em〉 〉 4.07 J/cm〈sup〉2〈/sup〉), the development of a thin rim surrounding an ablation crater into straight ridges spreading across the crater is observed for the formation of low spatial frequency LIPSS, suggesting a thermal and fluid process involved in the LIPSS formation. The results show that laser fluence plays a key role in controlling the origin of ripples, while pulse number mainly contributes to the subsequent growth of microstructures.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, the design of a three-layer linear polarization converter based on substrate-integrated waveguide (SIW) technology is demonstrated. The transmission-type polarization converter with dual frequency polarization conversion characteristics is realized by a square-slot sandwiched by two layers of off-center dipole-slot resonator, and its asymmetric transmission (AT) property can be obtained by rotating the upper and the lower dipole-slot resonator to form an interlaced layout. An excellent polarization conversion ratio (PCR) can be realized by integrating the traditional transmission-type polarization converter with an SIW, and its physical mechanism can be explicated by guided wave field theory. Experimental results are presented and compared with the simulation results, and they demonstrated that ultra-high PCRs of the presented polarization converter are 0.87 and 0.99 for the measurement at the working frequency of 7.34 GHz and the simulation at the working frequency of 7.6 GHz, respectively. The designed polarization converter has greatly expanded the application field of SIW technology.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, the effect of oxygen vacancies on structural and magnetic properties of La〈sub〉1.9〈/sub〉Sr〈sub〉0.1〈/sub〉CoMnO〈sub〉6〈/sub〉 (LSCMO) films deposited on Si (100) substrate was investigated by varying the oxygen partial pressure during film growth, by pulsed laser deposition. The Rietveld refinement manifest the monoclinic phase (with space group P21/n) of the bulk La〈sub〉1.9〈/sub〉Sr〈sub〉0.1〈/sub〉CoMnO〈sub〉6〈/sub〉 sample. A shift in ferromagnetic (FM) phases (〈em〉T〈/em〉〈sub〉c〈/sub〉) are obtained in both the LSCMO films from that of the bulk La〈sub〉1.9〈/sub〉Sr〈sub〉0.1〈/sub〉CoMnO〈sub〉6〈/sub〉 sample confirmed by a magnetic measurement. The oxygen vacancies, observed through X-ray photoelectron spectroscopy (XPS) measurement, can induce the local vibronic Mn〈sup〉3+〈/sup〉–O–Mn〈sup〉3+〈/sup〉 superexchange interactions in direct competition with static ferromagnetic Mn〈sup〉4+〈/sup〉–O–Mn〈sup〉4+〈/sup〉 interactions. In this paper, attempts have been made to tune the magnetic phases by controlling the oxygen vacancies.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Li〈sup〉+〈/sup〉 ion-doped BaTiO〈sub〉3〈/sub〉 (LBT-〈em〉x, x〈/em〉 = 0, 3%, 5%, 7%) ceramics were prepared by the solid-state reaction method, which were analyzed by XRD and EDS. The Ba〈sub〉2〈/sub〉TiO〈sub〉4〈/sub〉 phase was formed on the surface of sintered LBT-〈em〉x〈/em〉 ceramics with high Li〈sup〉+〈/sup〉 concentration (〈em〉x〈/em〉 = 5%, 7%), and tetragonal phase appeared after the removal of Ba〈sub〉2〈/sub〉TiO〈sub〉4〈/sub〉 surface layer. According to the results from first-principle calculation of 2 × 2 × 2 and 3 × 3 × 3 supercells, Li〈sup〉+〈/sup〉 ions can occupy B site of ABO〈sub〉3〈/sub〉 perovskite structure. The LBT-〈em〉x〈/em〉 (〈em〉x〈/em〉 = 3%, 5%, 7%) ceramics showed antiferroelectric-like double hysteresis loops which form [Li〈sub〉Ti〈/sub〉–〈em〉V〈/em〉〈sub〉o〈/sub〉]〈sup〉−〈/sup〉 dipoles and pin the domain walls. The piezoelectric constant 〈em〉d〈/em〉〈sub〉33〈/sub〉 also decreases due to pinning effect.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉A simplistic and environment-friendly approach has been used to prepare surfactant-free Mn-doped ZnO–glycerol nanofluids using high power sonicator. Thermal conductivity of the prepared nanofluids has been measured as a function of temperature and concentration. Maximum thermal conductivity enhancement ~ 32% at 40 °C has been observed with very low nanoparticles loading (2.0 vol% of Mn-doped ZnO-nanoparticles) which is significantly larger than the presently synthesized ZnO–glycerol nanofluids, and that of reported earlier on ZnO-ethylene glycol, and other glycerol-based nanofluids. Our present investigation shows that the thermal conductivity of nanofluids can be increased up to a significant level by changing other physical properties of incorporated nanoparticles than increasing concentration of nanoparticles to a large extent. Various physical phenomena including Brownian motion induced convection effect in conjunction with ballistic diffusion have been proposed for anomalous thermal conductivity enhancement. This may be valuable for various cooling applications and may open avenues for further exploration of efficient heat management with the help of nanosized doped metal oxide suspensions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Polycrystalline Ca〈sub〉12〈/sub〉Al〈sub〉14〈/sub〉O〈sub〉33〈/sub〉 was prepared by a solid state reaction method. All samples showed the phase of the Ca〈sub〉12〈/sub〉Al〈sub〉14〈/sub〉O〈sub〉33〈/sub〉 by X-ray powder diffraction (XRD). The Mg heat treatment and Sn doping contributions dominated to increase the lattice constant 〈em〉a〈/em〉 from 11.909(3) to 12.163(1) Å. Electron excitation energy of all samples were assigned by absorption spectra. The excitation energy between 2.68 and 2.79 eV was found after the Mg heat treatment. Electrical conductivity increased approximately 10〈sup〉9〈/sup〉 orders of magnitude at room temperature when experiencing Mg heat treatment for 10 h. The highest electrical conductivity obtained from the Ca〈sub〉12〈/sub〉Al〈sub〉12.8〈/sub〉Sn〈sub〉1.2〈/sub〉O〈sub〉33〈/sub〉/Mg(10) sample was 7.65 S cm〈sup〉− 1〈/sup〉 at 573 K. The low activation energy for electrical conductivity was approximately 0.038 eV as a result of the Mg heat treatment. The influence of the Sn doping excellence supported the increase of the electrical conductivity with the Mg heat treatment process.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Mono-Si textured surface covered with pyramids has been widely used in the solar cell. However, there are few reports of new microstructures instead of pyramids on Mono Si surface. By adding the special additive, we change the anisotropic texturing properties of alkaline solutions to develop a new small tower over Mono Si surface. The surface was evaluated by scanning electron microscopy, minority carrier lifetime instrument and integral reflector. The results show that this new microstructure has the minority carrier lifetime of 9.72 µs, reflectivity of 10.12% within 400–1000 nm, respectively, which are better than that of solar cell based on pyramids structure. By comparing with samples covered with pyramids, it is considered that the new microstructures are suitable for the possible applications of silicon solar cells. In addition, we also found the non-linear relationship between minority carrier lifetime and the tower size.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this paper, three commonly used methods for boron-rich layer (BRL) (BRL: abbreviation of boron-rich layer, a layer constituted by compound of boron and silicon.) removal and their impacts on the surface passivation and the efficiency of the final interdigitated back contact solar cells are investigated. The method of in-situ oxidation can remove BRL completely, but will cause serious degradation of the bulk lifetime. The method of treatment in boil nitric acid cannot remove BRL completely resulting in a poor passivation quality of the substrate surface. The method of chemical etch treatment (CET) (CET: Abbreviation of chemical etch treatment.) can remove BRL completely and would not cause any degradation of the bulk lifetime. Finally, interdigitated back contact solar cells have been fabricated using the three methods mentioned above for BRL removal and the highest efficiency of 21.17% is achieved with the BRL removed by the method of CET.〈/p〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉It is the prerequisite of improving the universality, stability, and wear resistance of superhydrophobic materials for the practical applications. A simple and environment-friendly method is developed herein for constructing superhydrophobic copper surface by hydrothermal method. The wettability, surface microstructure, phase structure, and chemical structure of superhydrophobic Cu〈sub〉2〈/sub〉S-coated copper surface are examined by contact angle measurement, SEM observation, XRD measurement, FT-IR and EDS analyses. Results show that the superhydrophobic Cu〈sub〉2〈/sub〉S-coated copper surface is composed of a large number of Cu〈sub〉2〈/sub〉S crystals grafted with long hydrophobic alkyl chains, and which leads to the superhydrophobic copper presenting a rough and hierarchical surface with micro- and nano-scaled binary structure. It is noteworthy that 200 °C of heat treatment has marked influence on the surface microstructure and wettability. Consequently, the mechanical durability of the superhydrophobic copper has been improved greatly upon heat treatment. Just ground on both the hierarchical surface and grafted long hydrophobic alkyl chains as well as heat treatment, the as-prepared superhydrophobic copper surface exhibits not only good mechanical durability and corrosion resistance, but also excellent chemical and UV durability as well as self-cleaning effect. This method provides a novel and simple process to protect the surface of copper. It is believed that such technique may open a new approach to expand the application of copper.〈/p〉 〈/span〉 〈span〉 〈h3〉Graphical abstract〈/h3〉 〈p〉A simple and environment-friendly method is developed for constructing superhydrophobic copper surface by hydrothermal method. Ground on both the hierarchical surface and grafted long hydrophobic alkyl chains as well as heat treatment, the as-prepared superhydrophobic surface exhibits not only good mechanical durability and corrosion resistance, but also excellent chemical and UV durability as well as self-cleaning effect.〈/p〉 〈p〉 〈span〉 〈span〉 〈img alt="" src="https://static-content.springer.com/image/MediaObjects/339_2019_2562_Figa_HTML.png"〉 〈/span〉 〈/span〉 〈/p〉 〈/span〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉In this study, SiO〈sub〉2〈/sub〉 gate dielectric operation was improved using SiO〈sub〉2〈/sub〉/capron nanocomposite. SiO〈sub〉2〈/sub〉/capron nanocomposite was synthesized by the sol–gel method. The existence of two phases in the nanocomposite structure was revealed using energy dispersive spectroscopy. The formation of hydrogen bonds among SiO〈sub〉2〈/sub〉 nanofillers and capron matrix was proved by Fourier transform infrared spectroscopy and thermogravimetric analysis. The fact resulted in the uniform dispersion of SiO〈sub〉2〈/sub〉 nanoparticles within capron matrix and the formation of cross-linked network. Pure SiO〈sub〉2〈/sub〉, pure capron, SiO〈sub〉2〈/sub〉/capron nanocomposite dissolved in benzene alcohol and SiO〈sub〉2〈/sub〉/capron nanocomposite dissolved in acid formic as the gate dielectric films were deposited on the p-type Si substrates. Atomic force microscopy showed a significant decrease in the average surface roughness of nanocomposite film (0.02 nm) compared to that of pure SiO〈sub〉2〈/sub〉 and pure capron films (18.3 and 7.85 nm, respectively). The operation of deposited films as the gate dielectrics was compared by the current–voltage (〈em〉I〈/em〉–〈em〉V〈/em〉) measurements in the metal–insulator–semiconductor structure. Fabricated p-type Si field-effect-transistors demonstrated a great decrease in the leakage currents and the threshold voltages by decreasing the surface roughness of their dielectric films, because the charge transport is strongly associated with trap depth and carrier scattering effects in the semiconductor/dielectric interface. As a result, the threshold voltages were shifted toward downward and reached 1 V for transistor based on SiO〈sub〉2〈/sub〉/capron nanocomposite dielectric film.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉This research investigates the effect of Pr〈sup〉3+〈/sup〉–Co〈sup〉2+〈/sup〉 substitution on the structural, optical, and electromagnetic interferrence (EMI) shielding properties of M-type strontium hexagonal ferrites with chemical composition Sr〈sub〉1−〈em〉x〈/em〉〈/sub〉Pr〈sub〉〈em〉x〈/em〉〈/sub〉Fe〈sub〉12−〈em〉y〈/em〉〈/sub〉Co〈sub〉〈em〉y〈/em〉〈/sub〉O〈sub〉19〈/sub〉 (〈em〉x〈/em〉 = 0.0, 0.2, 0.4 and 〈em〉y〈/em〉 = 0.00, 0.15, 0.35). The sample was prepared by sol–gel auto-combustion technique, pre-sintered at 400 °C for 4 h and sintered at 950 °C for 5 h. XRD analysis shows that the sample exhibits pure crystalline phase with no presence of impurity such as α-Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. The presence of three prominent peaks at 434, 543, and 586 cm〈sup〉−1〈/sup〉 in FTIR spectra indicates the formation of hexaferrite phase. FESEM micrographs depict nanoparticles with hexagonal plate-like structure of hexaferrites which is vital for microwaves absorption, whereas EDX spectra show the host and substituted ions. The observed band gap was found to decrease with increase in Pr〈sup〉3+〈/sup〉–Co〈sup〉2+〈/sup〉 concentration. The maximum EMI shielding effectiveness of 27.40 dB at 18 GHz was obtained for the sample S2 which is above the commercial level of 20 dB.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉We propose an efficient method for increasing the second harmonic (SH) generation by embedding the graphene (Gr) in SiO〈sub〉2〈/sub〉/MnF〈sub〉2〈/sub〉/ZnF〈sub〉2〈/sub〉 sandwich structure. The external magnetic field is perpendicular to the surface of MnF〈sub〉2〈/sub〉/Gr sandwich. Two cases where the Gr layer is put above or below the MnF〈sub〉2〈/sub〉 film are compared. For the MnF〈sub〉2〈/sub〉/Gr case, the numerical simulation results show that the SH outputs obviously increase one order magnitude compared with the MnF〈sub〉2〈/sub〉 sandwich without the Gr layer. In addition, the position and intensity of the SH outputs can be easily controlled by adjusting the external magnetic field strength and gate voltage. However, for the Gr/MnF〈sub〉2〈/sub〉 case, the SH outputs rapidly decrease almost near to zero. The electric field distributions show that, in this case, the light intensity in the MnF〈sub〉2〈/sub〉 film is further weakened, which causes that SH generations cannot be effectively excited. Besides, the effect of the magnetic field and the Fermi energy on the SH outputs are also studied.〈/p〉