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Metal-hydride solid state hydrogen storage (H-storage) has the advantages of high bulk density, good safety, easy operation and low operating cost, and is considered to be the most ideal H-storage method. High entropy alloys (HEAs), which contain at least five principal elements and each with an atomic percentage in the range of 5–35%, have gained continuous increasing attention in the material science community. Since large entropy encourages the generation of single-phase solid solutions with severe lattice distortions and more suitable reaction sites, HEAs have become a research hotspot for better performance in hydrogen storage. Body-centered cubic (BCC) alloy systems can theoretically store double amounts of hydrogen compared with commercial metal hydrides at room temperature, and BCC structural HEAs have shown the potential to reach this theoretic limit. The thermal conductivity of HEAs seriously affects its hydrogen storage performance, but little research has been conducted on the thermal conductivity of HEAs. In this study, as-cast ${\mathrm{\text{V}}}_{35}$Ti${}_{35}$Cr${}_{10}$Fe${}_{10}$M${}_{10}$ (M $=$ Mn, Co, Sc and Ni) HEAs were fabricated by arc-melting. The microstructure and thermal conductivity behavior of the HEAs were systematically investigated. It is found that the main phase of the HEAs is a BCC-structured solid solution. The alloys also have high thermal diffusivity, specific heat capacity and thermal conductivity. The ${\mathrm{\text{V}}}_{35}$Ti${}_{35}$Cr${}_{10}$Fe${}_{10}$Sc${}_{10}$ sample exhibit the highest thermal conductivity of $2.865\mathrm{\text{W}}/(\mathrm{\text{m}}\cdot \mathrm{\text{K}})$ at $100^{\circ }$C. The factors affecting the thermal conductivity of HEAs were systematically analyzed. This study provides a new perspective on alloys applied to solid-state hydrogen storage.

The structural, dielectric and piezoelectric properties of (1 − x)PbZr_0.52Ti_0.48O₃–xBaFe_0.5Nb_0.5O₃ ceramic system with the composition near the morphotropic phase boundary were investigated as a function of the BaFe_0.5Nb_0.5O₃ content by X-ray diffraction (XRD), dielectric measurement and piezoelectric measurement techniques. Studies were performed on the samples prepared by solid state reaction for x = 0.10, 0.12, 0.14, 0.16, 0.18 and 0.20. The XRD analysis demonstrated that with increasing BFN content in (1 − x)PZT_−xBFN, the structural change occurred from tetragonal to the mixture of tetragonal and cubic phase. Changes in the dielectric behavior and piezoelectric properties were found to relate with these structural changes depending on the BFN contents.

A high entropy alloy of composition CoCrCuFeNiAl_0.5 is mainly composed of a face centered cubic (FCC) solid solution phase. The tensile and compressive properties of the alloy were investigated; the alloy exhibited a tensile strength of 707 MPa, together with a large plastic strain limit of 19%.

The ternary system Zn_1-xCd_xO (x = 0.00, 0.01, 0.05, 0.10 and 0.15) samples have been synthesized by the solid solution route. The synthesized samples were characterized by their electrical, magnetic and dielectric properties. The resistivity of the samples decreases with increase of Cd concentration and temperature, respectively. The activation energy at 339 K varies from 0.426 to 0.146 eV. The ternary system possesses a negative mass susceptibility having pair of electrons confirmed by the magnetic mass susceptibility measurement. The dielectric constant of the samples increases with increase of Cd and decreases with frequency initially and then remains constant.

In this study, the synthesis of single crystals of solid solutions Ge${}_{1-x}$Si${}_x$ from the gas phase was performed in two different variants. Here, the vapor phase is created in a closed volume. A special ampoule has been made for this purpose. Ge–Si is placed near one end of the ampoule. A temperature gradient is created along the ampoule. The temperature of the hot zone was chosen to be $1050^{\circ }$C and the temperature of the cold zone to be $355^{\circ }$C. It has been found that single crystals can form not only on the polycrystalline layer, but also from separate centers on the walls of the ampoule.

Extruded samples of ${\mathrm{\text{Bi}}}_{85}{\mathrm{\text{Sb}}}_{15}$ solid solutions doped with 0.0005 at.% Te were obtained and the electrical conductivity $(\sigma )$, thermoelectric power (Seebeck) $(\alpha )$, Hall $(R_h)$ and thermal conductivity $(\chi )$ coefficients were investigated in the range $\sim 80$–300 K samples and magnetic field strength up to $74\times 10^4$ A/m, as annealed after extrusion, non-irradiated with gamma-quanta and the same samples irradiated with gamma quanta at different doses. It was found that at low doses (1 Mrad) of irradiation, radiation defects (RDs) appear in the samples which play the role of donor centers, as a result of which the concentration of free electrons $n$, and, consequently the electrical conductivity $\sigma$ increases, and the Seebeck coefficient $\alpha$ decreases. These defects, scattering the current carriers, reduce their mobility $\mu$. With an increase in the radiation dose, the concentration of defects also increases and free carriers are captured at the level of the RD. In this regard, the concentration of charged carrier defects $n$ and, consequently, $\sigma$ of the sample decrease, while the Seebeck coefficient and mobility increase. The effect of a magnetic field on the electrical and thermal parameters of extruded solid solution samples also depends on the radiation dose in the sample.

The electrical and thermal properties of extruded samples of Bi${}_{85}$Sb${}_{15}$$〈\mathrm{\text{Te}}〉$ modified with ZrO₂ were investigated depending on the dose of gamma radiation in the temperature range $\sim 80÷300$ K and magnetic field strength (H) $\sim 74\times 10^4$ A/m. It was found that an increase in the mobility in the irradiated modified Bi${}_{85}$Sb${}_{15}$$〈\mathrm{\text{Te}}〉$ is associated with the radiation introduction of acceptor (negatively charged) centers, which at low doses are generated mainly in the regions of the efficiency of impurity scattering of charge carriers and partially neutralized centers and, accordingly, to a certain increase in the mobility. In the extruded modified samples of the Bi${}_{85}$Sb${}_{15}$ solid solution, irradiation with gamma quanta results not only in the generation of radiation defects (RDs) (centers), but also accompanied by their rearrangement. This causes a change in the spectrum of localized states and the electron scattering process, which leads to corresponding changes in the presented electrical and thermal parameters.

The ${\text{CoSb}}_{0.82}$–Sn section of the Co–Sb–Sn ternary system was studied by methods of physicochemical analysis. It is shown that the section is quasi-binary, its phase diagram is of a simple eutectic type, with a limited region of solid solutions based on ${\text{CoSb}}_{0.82}$, the boundary of which at room-temperature reaches $\sim 1$ mol% Sn. The temperature dependences of some thermoelectric parameters of (${\text{CoSb}}_{0.82}$)${}_{1-x}$${\text{Sn}}_x$ solid solutions have been studied. The thermodynamic functions of a pure ${\text{CoSb}}_{0.82}$ and a solid solution alloy of composition (CoSb${}_{0.82}$)${}_{0.99}$Sn${}_{0.01}$ are calculated.

In this work, we study the influence of the temperature on the mechanism of current transfer in the reverse branch of the current–voltage (I–V) characteristics of n-CdS/p-CdTe heterostructures. The study of the heterostructure, using the technique of on energy-dispersive X-ray analysis, showed that a layer of CdS_xTe${}_{1-x}$ is formed at the boundary of the heterojunction with a varying composition, being equal $x\approx 0.48$ from the side of CdS and $x\approx 0.02$ from the CdTe side. In the studied range of the temperatures and bias voltage, the current-voltage characteristics are described well by a power law $J=A{V}^{\alpha }$, where the exponent $\alpha$ changes with the temperature and voltage. Under the influence of the temperature and charge carrier concentration, the mechanism of current transfer in the structure changes from exclusion ($\alpha \approx 0.5$) to ohmic ($\alpha \approx 1$), and then goes to injection ($\alpha \approx 2$). The inhomogeneous intermediate CdS_xTe${}_{1-x}$i-layer at the boundary of the n-CdS/p-CdTe heterostructure is characterized by the presence of metastable states that rearrange at high temperatures and certain charge carrier concentrations. As a result of this, the exclusion slows down and electrons are injected from the rear molybdenum contact.

The effect of thermal heat treatment on the mechanical and electrical properties of Cu–Ag alloys was investigated. The homogenization heat treatment leads to an increase in tensile strength and a decrease in electrical conductivity due to dissolution of Ag into copper matrix. Also, it is shown that electrical conductivity of as-cast Cu–Ag alloys decreases with increasing Ag content. In contrast, the aging heat treatment gives rise to increase both the tensile strength and electrical conductivity because the Ag solute diffuses out from copper matrix during aging heat treatment. Therefore, it can be mentioned that the electrical conductivity of Cu–Ag alloys depends on Ag solute in copper matrix. Also, aging treatment is favorable to acquire high strength and high electrical conductivity.

The paper presents results of studies of the formation of phases during the solid-state synthesis in the [(${\mathrm{\text{Na}}}_{0.5}{\mathrm{\text{Bi}}}_{0.5}{)}_{0.80}{\mathrm{\text{Ba}}}_{0.20}]({\mathrm{\text{Ti}}}_1–{}_y{\mathrm{\text{B}}}_y){\mathrm{\text{O}}}_3$ system of solid solutions with $B$-site substitutions. The substitutions by zirconium, tin and ion complexes (In${}_{0.5}$Nb${}_{0.5})$ and (Fe${}_{0.5}$Nb${}_{0.5})$ have been studied. It has been found that the synthesis is a multi-step process associated with the formation of a number of intermediate phases (depending on the compositions and calcination temperatures). Single-phase solid solutions have been produced at the calcination temperatures in the interval 1000–1100${}^{\circ }$C. An increase in the substituting ions concentration leads to a linear increase of the crystal cell size. At the same time, the tolerance factor gets reduced boosting the stability of the antiferroelectric phase as compared to that of the ferroelectric phase.

In this paper, the influence of toluene as the process control agent (PCA) and pre-milling on the extension of solid solubility of 7 wt.% Cr in Cu by mechanical alloying in a high energy ball mill was investigated. The structural evolution and microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, respectively. The solid solution formation at different conditions was analyzed by copper lattice parameter change during the milling process. It was found that both the presence of PCA and pre-milling of Cr powder lead to faster dissolution of Cr. The mean crystallite size was also calculated and showed to be about 10 nm after 80 hours of milling.

The structural, dielectric and piezoelectric properties of (1 - x)PbZr_0.52Ti_0.48O₃-xBaFe_0.5Nb_0.5O₃ ceramic system with the composition near the morphotropic phase boundary were investigated as a function of the BaFe_0.5Nb_0.5O₃ content by X-ray diffraction (XRD), dielectric measurement and piezoelectric measurement techniques. Studies were performed on the samples prepared by solid state reaction for x = 0.10, 0.12, 0.14, 0.16, 0.18 and 0.20. The XRD analysis demonstrated that with increasing BFN content in (1 - x)PZT_-xBFN, the structural change occurred from tetragonal to the mixture of tetragonal and cubic phase. Changes in the dielectric behavior and piezoelectric properties were found to relate with these structural changes depending on the BFN contents.