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Metallic zirconium based glasses are a new promising family of materials characterized by high strength and comparatively high plasticity in compression tests. In recent years, great attention has been paid to the application of different regimes for the treatment of metallic glasses for the formation of a unhomogeneous amorphous structure to increase the plasticity of these materials. In this study, amorphous Zr62.5Cu22.5Fe5Al10 alloy bands were manufactured by the method of quenching on a rotary copper disk. The effect of hot rolling and further annealing at a temperature of 300°C for 150 min on the structure and properties of these bands was investigated. To study the transformation occurring in their structure as a result of thermomechanical treatment, transmission electron microscopy and X-ray diffraction were used. The effect of thermomechanical treatment on the mechanical properties of bands was studied by measuring the Vickers microhardness. Based on the obtained results, some conclusions about the effect produced by the microstructure of bands on the microhardness of the Zr62.5Cu22.5Fe5Al10 alloy were made. In this study, an abrupt increase in the microhardness was observed after thermomechanical treatment, due to the formation of nanosized uniformly distributed areas in the structure.

t—The diffusion welding of ultrafine-grained pseudo-α-titanium Ti–4.73% Al–1.88% V alloy specimens has been performed by spark plasma sintering. It has been shown that the destruction of welded joints in the ultrafine-grained (UFG) specimens under hot salt corrosion (HSC) conditions has a two-stage character: intercrystallite corrosion (ICC) is developed at the first stage to turn into pitting corrosion at the following stage. It has been established that the resistance to intercrystallite corrosion is governed by the concentration of vanadium on grain boundaries, the size and volumetric content of β-phase particles, and the existence of pores in a welded joint. It has been demonstrated that the welded joints of the ultrafine-grained specimens have higher hardness and resistance to intercrystallite corrosion as compared to coarse-grained specimens.

A new polytype of the quasi-one-dimensional conductor NbS3 with high-temperature charge density waves has been synthesized. The transmission electron microscopy study at room temperature has revealed only one of the two superstructures existing in the previously studied monoclinic phase with the period along chains close to b/0.352. In addition, a new incommensurate distortion of the lattice with the period close to 2b has been observed. The transport properties of the samples under study are in agreement with the study of the superstructure. The main lattice constants are somewhat different from the respective parameters in the previously studied monoclinic phase. The new phase can assumingly be intermediate between the two main known phases of NbS3, monoclinic and triclinic. Its properties can be explained within a model where a unit cell of the monoclinic phase can be considered as the superposition of unit cells of the triclinic phase.

Electrocatalysts based on Pt-M bimetallic nanoparticles deposited on carbon supports have already been used in commercially available Proton Exchanged Membrane Fuel Cells (PEM FC). Nevertheless, production and practical use of such materials faces with the problems caused by the need to combine high specific activity in current-forming reactions and their durability, with the stability of the element's composition during the operation of PEM FC. The suggested stepwise approach to the PtCu/C materials synthesis in the liquid phase is based on the initial deposition of platinum nuclei and their subsequent growth due to the joint or sequential deposition of copper and platinum from the solutions of their precursors. The PtCu/C catalysts, obtained in this way, demonstrated not only higher activity in oxygen reduction reaction compared to the commercial Pt/C catalyst, but also a significantly higher corrosion-morphological stability.

The phenomenon of post-aging retrogression in magnesium alloys containing two rare-earth metals belonging to different groups, i.e., yttrium Y (the yttrium group) and samarium Sm (the cerium group), is investigated. It is shown that retrogression may occur in alloys with different proportions of yttrium and samarium aged at 200°C for maximum hardness and then annealed at somewhat higher temperatures (250 and 300°C). The process is possible due to decomposition of the supersaturated magnesium solid solution. The degree of the retrogression is shown to depend on the temperature and duration of the post-aging annealing and on the yttrium- to-samarium proportion in the alloys.

The effect of heat treatment at 1000°C for 400 h on the thermal conductivity of zirconium dioxide crystals stabilized with scandium oxide (ZrO2)1 – x(Sc2O3)x (x = 0.08–0.10) and simultaneously with scandium and yttrium oxides (ZrO2)1 – x – y(Sc2O3)x(Y2O3)y (x = 0.003–0.20, y = 0.02–0.025) has been studied. In the crystals of zirconium dioxide stabilized with scandium oxide, the most noticeable changes in the thermal conductivity are observed in the 9ScSZ crystals, in which the phase composition is changed and a marked content of the rhombohedral phase appears. These changes are less noticeable in the 8ScSZ crystals and they are mainly due to the ordering of oxygen vacancies and the changes in the microstructures of the samples, and there are no changes in the 10ScSZ crystals. The 10ScSZ crystals have the minimum electrical conductivity before and also after annealing, which is determined by the highest content of scandium oxide in the solid solution. Insignificant changes in the thermal conductivity are observed in crystals of partially stabilized zirconium dioxide co-alloyed with scandium and yttrium oxides. The cubic 8Sc2YSZ and 10Sc2YSZ crystals demonstrate only slight changes in the thermal conductivity, the character of the temperature dependence of the thermal conductivity, and the phase compositions. The alloying of the zirconia–based solid solutions with yttrium oxide simultaneously with scandium oxide enables one to increase the stability of their phase compositions and structurally dependent thermal and electrical physical characteristics.

Due to their tunable current–voltage characteristics, Zn-doped thin SiO2 films are promising for microelectronic devices, e.g., memristors. In this work we studied single-crystal Si (100) substrates with 200 nm SiO2 surface layers implanted with 64Zn+ using Zn K-edge x-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM) and electron diffraction. We used two specimens: as-implanted and annealed in oxygen at 700°C. Cross-section TEM analysis showed that 64Zn+ implantation leads to the formation of a subsurface layer consisting of Zn nanoparticles approximately 7 nm in size. The nanoparticles are distributed in depths from 10 nm to 90 nm, with a concentration peak at 45 nm. Electron microscopy showed that most of the Zn nanoparticles are amorphous. However, XAS data indicated that almost all the Zn atoms are coordinated with oxygen. Thus, only a small fraction of zinc atoms are involved in the formation of nanoclusters. Annealing at 700°C leads to the oxidation of particles with the formation of the Zn2SiO4 phase. The particle sizes in the surface layer of SiO2 after annealing vary from 3 nm to 20 nm.

Titanium alloys are widely used as materials for the elements of nuclear power plants, which are subject to high reliability requirements. The goal of the study is to develop X-ray diffraction analysis of the phase composition of α - and near- α -titanium alloys. Surface treatment of the samples of titanium alloys PT-3V, PT-7M and VT1-0 was carried out by mechanical, electrochemical polishing and chemical etching. It is shown that PT-3V and PT-7M alloys are characterized by a mixed structure consisting of α - and α ’-phases with precipitation of submicron particles of the β -phase along the grain boundaries. The results of X-ray diffraction analysis of the samples obtained on an X-ray diffractometer Shimadzu XRD-7000 (Cu K α radiation) were compared with the data of metallography and electron microscopy. It is shown that the results of X-ray diffraction analysis strongly depend on the method, quality and duration of the surface treatment of the samples. Electrochemical polishing and acid treatment reduce the width of diffraction peaks and lead to a more pronounced manifestation of their «fine» structure thus demonstrating the presence of at least two crystalline phases in the alloys. «Splitting» of the main X-ray peaks of titanium is a consequence of the fine structure of primary X-ray radiation ( K α 1,2 -doublet). Presence of «fine» structure of X-ray peaks and correlation between the intensities of different peaks appears to depend essentially on the mode and quality of surface treatment of the titanium alloy thus reducing the reliability of quantitative analysis of the phase composition of titanium alloys without verification of the results by direct methods of studying alloy structure.

In this work we explored the possibility of obtaining single-phase β-Zn4Sb3 material by direct melting and spark plasma sintering (SPS). The effect of the SPS conditions and synthesized material composition on the structure and thermoelectric properties of the material was studied. X-ray diffraction was used for phase analysis, and scanning electron microscopy was used for characterizing the morphology of the bulk samples. We found electro-migration of Zn due to the exposure to DC pulses during SPS at 40 MPa. Zinc electro-migration produced a zinc-excess layer on the sample surface on the cathode side and a zinc-depleted layer, i.e., ZnSb, on the anode side of the sample. We show that an increase in the sintering pressure, and hence a decrease in the electric current passing through the material, produces single-phase β-Zn4Sb3 material in the entire sample bulk, provided the synthesized material contains excess zinc. The highest ZT of ∼ 1.28 at 673 K was obtained for the material synthesized with Zn excess and sintered by SPS at a pressure of 100 MPa.

The temperature dependence of the thermal conductivity of cubic ZrO2 single crystals stabilized with yttrium oxide from 8 to 40 mol % has been studied in the temperature range 50–300 K. The dependence is analyzed taking into account the phase compositions, the features of the local structures and the electrophysical characteristics of these single crystals.

It is shown based on the structural analysis by reciprocal space mapping and the experimental secondary ion mass spectrometry and transmission electron microscopy data that, along with lateral compressive stress, vertical compressive stress is induced in a multilayer epitaxial heterostructure with a metamorphic step-graded buffer. The reason for this stress is that interphase boundaries hinder complete stress removal at strain relaxation. The analysis carried out within the linear elasticity theory showed that the elastically strained state of the heterostructure layers is similar to the state arising during a two-stage deformation process (bulk and biaxial compression). It is shown that the free energy of the system in the metastable state is minimal in this case.

The thermal conductivity of single-crystal solid solutions (ZrO2)1 – x – y – z(Sc2O3)x(CeO2)y(Y2O3)z (x = 0.08–0.10; y = 0.005–0.01; z = 0–0.005) was measured in the temperature range 50–300 K. Phase composition and defective structure of crystals were studied.

The results of investigating the crystal structure, ionic conductivity, and local structure of the (ZrO2)1 –x(Gd2O3)x and (ZrO2)1 –x(Y2O3)x (x = 0.04, 0.08, 0.10, 0.12, and 0.14) solid solutions are reported. The crystals are grown by directional crystallization of the melt in a cold container. The phase composition of the crystals is investigated by X-ray diffractometry and transmission electron microscopy. The transport characteristics are studied by impedance spectroscopy in the temperature range of 400 to 900°C. The local crystal structure is examined by optical spectroscopy. Eu3+ ions were used as a spectroscopic probe. The study of the local structure of the ZrO2–Y2O3 and ZrO2–Gd2O3 solid solutions revealed the features in the formation of optical centers, which reflect the character of localization of oxygen vacancies in the crystal lattice depending on the stabilizing oxide concentration. It is established that the local crystal environment of Eu3+ ions in the (ZrO2)1 –x(Y2O3)x and (ZrO2)1 –x(Gd2O3)x solid solutions is determined by the stabilizing oxide concentration and is practically independent of the stabilizing oxide type (Y2O3 or Gd2O3). The maximum conductivity at a temperature of 900°C is observed in the crystals with 10 mol % of Gd2O3 and 8 mol % of Y2O3. These compositions correspond to the t'' phase and are close to the interface between the cubic and tetragonal phase regions. It is found that in the ZrO2–Y2O3 system the highly symmetric phase is stabilized at a lower stabilizing oxide concentration than in the ZrO2–Gd2O3 system. The analysis of the data obtained makes it possible to conclude that, in this composition range, the concentration dependence of the ionic conductivity is mainly affected by the phase composition rather than the character of the localization of oxygen vacancies in the crystal lattice.

On the basis of data on X-ray structural analysis performed by the method of reciprocal-space mapping and investigations using secondary-ion mass spectrometry and transmission electron microscopy, it is shown that vertical compressive stresses also arise in a multilayer epitaxial heterostructure comprised of a step-graded metamorphic buffer along with lateral compressive stresses. The cause of the appearance of vertical stresses is the effect of interlayer hardening, which arises due to the deceleration of fragments of glide dislocations by interphase boundaries. Analysis performed within the framework of the linear theory of elasticity shows that the elastically stressed state of the buffer steps is similar to the state that can be achieved as a result of a two-stage deformation process: bulk and biaxial compression. Bulk compression leads to large energy expenditures in the formation of the structure of the buffer steps, which is reflected, in particular, in violation of the coherence between the dislocation-free and the underlying layers.

The development of aluminum alloys with superior mechanical properties and high strain rate superplasticity is an important prerequisite for advancing applications of superplastic blow-forming technology. This study focuses on the effect of Ce and Fe additions on the microstructural parameters and tensile properties of a superplastic Al-4.8%Mg-0.6%Mn-0.15%Cr (AA5083-type) alloy. The studied alloy exhibits a bimodal particle size distribution with coarse crystallization origin inclusions and fine secondary precipitates. Both the coarse and fine particles lead to grain refinement. The coarse Ce-, Fe-, and Mn-rich intermetallic particles of crystallization origin provide evidence of a particle-stimulated nucleation effect. The semi-coherent Mn-enriched compact-shaped dispersoids with an Ashby-Brown contrast, a quasicrystalline structure, and a mean size of 38 nm are precipitated after low-temperature homogenization and exhibit a strong Zener pinning effect. The proposed thermomechanical treatment results in the development of a grain size of 4 μm and an ultimate tensile strength of 340 MPa in the recrystallized sheet. The superplastic deformation behavior in a strain rate range of 1 × 10−2 to 1 × 10−1 s−1 and the associated strain-induced changes in the grain structure and mechanical properties of the developed alloy are presented and discussed.

The effect of high-pressure torsion (HPT) on the structural and phase transformations in a new eutectic aluminium alloy (94.9%Al; 3.5%Ca; 0.9%Mn; 0.5%Fe; 0.1%Zr; 0.1%Sc) was studied. HPT leads to the formation of a nanocrystalline structure with a predominant grain size of 11–34 nm. HPT causes the refining of eutectic [(Al) + Al4Ca] and the formation of nanoclusters and segregations. The phase composition of the alloy after HPT tends to the phase composition at elevated temperatures.

Polycrystalline thermoelectric elements of n-type Bi2(Te0.95Se0.05)3 and p-type (Bi0.25Sb0.75)2Te3 were fabricated by modified Bridgman technique, followed by electrospark cutting. A thermoelectric micromodule, consisting of 12 legs with an Ni anti-diffusion barrier and high-temperature SnSb solder between them, was assembled. To investigate thermoelements under conditions close to operating ones, the micromodule was annealed at 443 K for 1000 h. It was revealed that after annealing for more than 40 h, the near-contact zone of the n-type legs degraded, leading to a complete break of the micromodule junctions. Our results revealed that during annealing, the SnSb solder flowed into the unprotected side surface of the legs, and contacted with the cleavage planes along which tin can diffuse into the thermoelement volume. In contrast, the p-type legs were not affected by the contact with the solder. Different impacts of the solder on n- and p-type legs were explained in the framework of density functional theory (DFT) calculations. Substitution, diffusion and thermodynamic stability calculations showed that Bi to Sn substitution is energetically more beneficial than Sb to Sn substitution. Additionally, it was calculated that for the Bi2Te3 + Sn system, it is more beneficial to form a TeSn and Bi phase, while an Sb2Te3 + Sn system is thermodynamically stable.

A layered metallic hybrid material based on vanadium and zirconium alloys was obtained by high pressure torsion (HPT) at room temperature. HPT of the initial three-layer V-10Ti-5Cr alloy/Zr-2.5Nb alloy/V-10Ti-5Cr alloy billet resulted in a “mixing” of the zirconium alloy layer with vanadium alloy layers. A mixed nanostructure consisting of elongated grains (fragments) with a width of 40–50 nm was formed in the zirconium/vanadium alloy layers of the hybrid. Partial amorphization in the zirconium alloy layer of the hybrid material was found.

The thermal conductivity of single-crystal (ZrO2)1 – x(Sc2O3)x (x = 0.09, 0.10) and (ZrO2)1 ‒ x ‒ y(Sc2O3)x(Y2O3)y (x = 0.003–0.10; y = 0.01–0.025) solid solutions has been experimentally determined in the temperature range 50–300 K. The results are analyzed with allowance made for the phase compositions and features of imperfect crystal structures.

We carry out an experimental-theoretical study of the process of the equal-channel angular pressing (ECAP) to obtain a bismuth-telluride-based thermoelectric (TE) material. A brief review of the mathematical modeling of the ECAP process is given, and the effect of the design features and temperature of ECAP regimes on the formation of plastic is studied. The results of calculations of the thermally stressed state of the samples at different stages of the ECAP process are presented. The calculations for the ECAP process are carried out using the Lagrange finite element mesh. During the calculation, the mesh is adjusted to the geometry of the die, becoming rarer or finer depending on the magnitude of the plastic deformation to satisfy the specified calculation accuracy and the convergence of the iterative process. We discuss the results of an experimental study of the structure and properties of the samples obtained with the help of ECAP using various methods (X-ray diffractometry and scanning electron microscopy). The TE characteristics of the obtained materials are measured by the Harman method. Comparative methodological calculations of the ECAP process for a bismuth-telluride-based TE material with a change in the parameters determining the formation of grains are performed (the critical plastic deformation as a function of temperature and the power-law dependence of the rate of this deformation). This allowed us to adjust the design model of the ECAP process using the grain size measurements in the TE material. The results of the calculation of the process of grain formation at different temperatures of plastic molding are presented and compared with the experimental data. The practical result of this research is the improved geometry of the die punch and the validated technological regimes of plastic deformation, which allowed obtaining samples with high TE efficiency values.

—The Cu2 – xSe (0.03 ≤ x ≤ 0.23) powders fabricated by mechanochemical synthesis have been studied by X-ray diffraction. The in situ study has been carried out for the temperature dependences of the lattice parameters, the structures, and the phase compositions of the powders in the temperature range 25–350°C. The powder compositions are shown to differ from the charge compositions and are shifted to lower copper concentrations. The estimation of peak half-widths of the cubic β phase indicates an increase in the structure imperfection after the phase transition from the α phase to the β phase of Cu2 – xSe at ~140°C. It is shown that the superpositions of the subtraction solutions (copper vacancies) and interstitials solutions (copper atoms in interstitial sites), whose proportion is changed as a function of temperature and the deviation from stoichiometry, are in the thermodynamic equilibrium in the copper selenide solid solution at room temperature. The change in the slope of the dependence of the lattice parameter of the powder Cu2 – xSe samples on the composition (0.03 ≤ x ≤ 0.23) in the temperature range 25–350°C enables the suggestion that interstitial copper atom concentration increases with temperature and deviation from stoichiometry.

In this work we report a study of (ZrO2)1−x−y(Sc2O3)x(СeO2)y solid solution crystals (x = 0.08–0.10; y = 0.005–0.015) grown by skull melting technique. The crystal structure of the material was studied using X-ray diffraction, Raman spectroscopy and impedance spectroscopy. The study showed that optically homogeneous and transparent crystals cannot be grown from the melt in the experimental composition range. For overall stabilizing oxide concentrations of above 10 mol% the crystals contained a cubic phase and a rhombohedral one, whereas at concentrations of lower than 10 mol% a cubic and a tetragonal phases coexisted. Ceria introduction into the (ZrO2)1−x(Sc2O3)x system increases its high-temperature ionic conductivity. The highest ionic conductivity was observed in 0.5 mol% ceria containing crystals.

Increasing the recrystallization resistance and the mechanical properties of aluminum-based alloys is possible due to the formation of a nanoscale L12-structured Al3Zr phase. Treatment conditions and alloys composition affect the size and density of dispersoids and their final properties. In this work we analyze the decomposition of the supersaturated solid solution in the as-cast Al-3%Mg-0.25%Zr alloy for different annealing modes to understand the precipitation kinetics of the Al3Zr phase in the presence of Mg. We found that both discontinuous and continuous precipitation mechanisms of the Al3Zr phase are possible in the studied low-alloyed material. One-step annealing leads to the formation of coarse (17 nm) spherical precipitates of a coherent L12-structured Al3Zr phase and discontinuously formed fan-shaped aggregations of the same phase. Two-step annealing provided for the maximum precipitation hardening with the formation of high-density nanoscale (7 nm) dispersoids of the Al3Zr phase. This study highlights the importance of the annealing mode of the as-cast material for achieving a high density of the fine L12 structured Al3Zr phase and the maximum hardening effect.

The architecture of bimetallic nanoparticles has strong influence on durability and activity of PtM/C electrocatalysts in the oxygen electroreduction (ORR) and the methanol electrooxidation reactions (MOR). In the present study the Pt0.8(Cu)/C electrocatalyst was obtained by the methods of successive multistage reduction of platinum and copper from the solutions of their precursors while platinum concentration in the matrix solution was increasing step by step. The composition, structural characteristics and electrochemical behavior of this material were compared with the Pt1.0Cu/C catalyst based on the nanoparticles of a solid solution, which was obtained by the combined single-step chemical reduction of precursors, as well as with a commercial Pt/C sample with the same Pt-loading (20% by weight). The catalyst based on the Pt–Cu gradient nanoparticles demonstrated the highest corrosion-morphological stability in the stress-test, as well as the highest activity in ORR and MOR in the HClO4 solutions. Both of the studied bimetallic catalysts lose a significant amount of copper during the standardizing cycling and the stress-test. In the stabilized composition of the “gradient catalyst” the residual copper content, however, is considerably higher than that of the catalyst with the solid solution nanoparticles. The positive features of the electrochemical behavior of Pt0.8(Cu)/C catalyst arise apparently due to the faster formation of a durable protective layer of platinum on the surface of nanoparticles in the process of functioning, compared to the analogue based on the nanoparticles of the solid solution. High stability and activity of Pt0.8(Cu)/C compared to the Pt/C analogue are associated with the larger size of the nanoparticles and the promoting influence of residual copper on the catalytical activity of platinum.

The properties of nanorods made of high-energy-gap Zn x Mg1 – xO semiconductors are experimentally investigated using the new system of 3D manipulation of individual nanospecimens. The technology used to prepare Zn x Mg1 – xO nanorods via gas-phase deposition on a substrate, the process whereby individual nanorods are selected by means of nanocomposite tweezers with the shape-memory effect in the vacuum chamber of a two-beam scanning microscope, and the results obtained when their structure and morphology are experimentally studied using transmission electron spectroscopy are described. The prospects that nanophotonic, nanosensorial, and nanoelectronic devices can be fabricated from Zn x Mg1 – xO nanorods via the new nanomanipulation technique are discussed.

The structure and mechanical properties of the crystals of solid solutions of zirconium dioxide, which are stabilized by yttrium and cerium oxides, have been studied. The electron paramagnetic resonance technique has been used to identify Ce3+ ions and to determine their relative concentration in the crystals. It is shown that the presence of Ce3+ ions in the crystals is the main factor responsible for their high fracture toughness. The annealings carried out during investigations, which lead to a decrease in the concentration of Ce3+ ions, show that a change in the valence state of cerium ions lowers the fracture toughness of the crystals.

Spatial distribution of residual elastic strain in the layers of two step-graded metamophic buffers of various designs, grown by molecular beam epitaxy from ternary InxAl1–xAs solutions on GaAs(001) substrates, is obtained using reciprocal space mapping by three-axis X-ray diffractometry and the linear theory of elasticity. The difference in the design of the buffers enabled the formation of a dislocation-free layer with different thickness in each of the heterostructures, which was the main basis of this study. It is shown that, in spite of the different design of graded metamorphic buffers, the nature of strain fields in them is the same, and the residual elastic strains in the final elements of both buffers adjusted for the effect of work hardening subject to the same phenomenological law, which describes the strain relief process in single-layer heterostructures.

This work shows the correlation between the crystal structure, phase composition and transport characteristics of ZrO2 based solid electrolytes depending on the concentration of the stabilizing impurity Y2O3. The crystals ZrO2 stabilized with yttrium oxide in a wide range of compositions (from 2 to 15 mol% Y2O3) were studied. The phase composition, twin structure, and conductivity of the crystals we determined for all concentrations by X-ray diffraction, transmission electron microscopy, Raman and impedance spectroscopy. The ionic conductivity of the crystals was changed nonmonotonic, with increasing Y2O3 concentration. The existence of two maxima of ionic conductivity at temperatures 800–900 °C for compositions ZrO2-3.2 mol% Y2O3 and ZrO2-8 mol% Y2O3 was established. We show that twin boundaries do not trigger any additional ionic conductivity acceleration mechanism in ZrO2-Y2O3 crystals. The highest conductivity is observed in ZrO2-(8–10) mol% Y2O3 crystals containing the t″ phase in which the oxygen atoms are shifted from the high symmetry positions that are typical for the cubic phase.

New promising functional materials—amorphous-crystalline fast-quenched Ti2NiCu alloys exhibiting the shape memory effect (SME)—are studied. A method for annealing amorphous alloys by electric current pulses is proposed. This method allows one to obtain the needed degree of crystallinity. It is demonstrated that a microcrystalline structure with spherical grains exists in amorphous-crystalline samples. These grains increase in size from 150 nm to 3.2 μm as the degree of annealing increases. The SME is not observed in nontreated samples and is clearly manifested in completely annealed samples. A two-way SME and a trend toward lowering of the martensitic transition temperature are observed in partially annealed samples.

PtCu/C electrocatalysts with bimetallic PtCu nanoparticles were synthesized by successive chemical reduction of Cu2+ and Pt(IV) in a carbon suspension prepared based on an aqueous ethylene glycol solution. The atomic structure of as-prepared PtCu nanoparticles and nanoparticles subjected to thermal treatment at 350°C was examined using PtL 3 and CuK EXAFS spectra, transmission electron microscopy (TEM), and X-ray powder diffraction (XRD). The results of joint analysis of TEM microphotographs, XRD profiles, and EXAFS spectra suggest that the synthesized electrocatalysts contain PtCu nanoparticles with a Cu core–Pt shell structure and copper oxides Cu2O and CuO. Thermal treatment of electrocatalysts at 350°C results in partial reduction of copper oxides and fusion of bimetallic nanoparticles with the formation of both homogeneous and ordered PtCu solid solutions.

The temperature dependences of the specific heat, thermal conductivity, coefficient of thermal expansion (CTE), and transport coefficients (electrical conductivity and thermoelectric power) of copper selenide are experimentally and theoretically investigated in the temperature range of 300–873 K. The calculation results correlate with the experimental data up to a temperature of ~773 K. The maximum thermoelectric figure of merit of nanostructured copper selenide is ZT ~ 1.8. The correlation dependence between ZT and the thermal conductivity within the entire temperature range under consideration is shown.

The effect of synthesis conditions on the structure and thermoelectric properties of zinc-antimonide- based materials is investigated. The effects of Zn excess, the modes of spark plasma sintering, and In doping on the phase composition and the thermal stability of the properties of the obtained material are considered. The material is prepared by the method of the direct alloying of components and spark plasma sintering. It is shown that, at certain modes of spark plasma sintering, the introduction of an excess amount of Zn and In doping make it possible to obtain β-Zn4Sb3 with the thermoelectric efficiency ZT ≈ 1.47 at a temperature of 720 K, which shows the stability of characteristics under the performed tests.

Using the methods of powder X-ray diffraction, transmission electron microscopy, and EXAFS spectroscopy, the phase behavior of bimetallic Pt–Cu nanoparticles with different architecture that are deposited on a highly disperse carbon carrier has been investigated during their thermal treatment in inert atmosphere. It is established that Pt–Cu nanoparticles with a Cu-core–Pt-shell structure rearrange into nanoparticles with a Pt–Cu solid-solution structure in the temperature range from 280 to 300°C. This transformation is accompanied by a sharp change in the unit-cell parameter. Such a change in the crystal lattice parameter does not occur during the thermal treatment of material with similar composition containing Pt–Cu nanoparticles with a solid-solution structure. The results can be used in elucidating the structure of Pt–M/C materials with different nanoparticle architectures.

Ground chips of as-cast Al-10 wt.% Zr alloy were subjected to mechanical alloying (MA) with 5 vol.% of nanodiamond addition in a high energy planetary ball-mill. The aim of this work was to investigate the microstructure, phase transformation and mechanical properties of the material both after MA and after subsequent annealing. Optical and transmission electron microscopes were used for morphological and microstructural analysis. The effect of milling time on powder microhardness, Al lattice parameter, lattice microstrain and crystallite size was determined. It was shown that mechanical alloying of as-cast Al-10wt.%Zr alloy during 20 h leads to a complete dissolution of the primary tetragonal Al3Zr crystals in aluminum. At the same time, the powder microhardness increases to 370 HV. Metastable cubic Al3Zr phase nanoparticles precipitate from the Al solution due to its decomposition after annealing, however, the Al solid solution remains supersaturated and nanocrystalline. Compression tests at room temperature and at 300 °C showed that the strength values of the hot-pressed samples reach 822 MPa and 344 MPa, respectively.

For the first time crystals of the (ZrO 2 ) 1− x − y (Sc 2 O 3 ) x (Y 2 O 3 ) y solid solutions ( x =0.08–0.11; y =0.01–0.02) have been grown by directional melt crystallization. We have determined the range of melt compositions for which growth from the melt produces of the (ZrO 2 ) 1 − x − y (Sc 2 O 3 ) x (Y 2 O 3 ) y solid solution single crystals. The single-phase optically transparent single crystals following composition were grown: (ZrO 2 ) 0.9 (Sc 2 O 3 ) 0.08 (Y 2 O 3 ) 0.02 ; (ZrO 2 ) 0.89 (Sc 2 O 3 ) 0.09 (Y 2 O 3 ) 0.02 ; (ZrO 2 ) 0.89 (Sc 2 O 3 ) 0.10 (Y 2 O 3 ) 0.01 ; (ZrO 2 ) 0.88 (Sc 2 O 3 ) 0.10 (Y 2 O 3 ) 0.02 . Comprehensive study of the crystal structure by using XRD, transmission electron microscopy, and Raman spectroscopy revealed that the all single crystals, which is identified by XRD data as cubic one, in fact have t″ tetragonal structure, which forms by small displacement of oxygen ions along the c -axis. Data on the phase stability of the crystals during mechanical crushing were obtained. The electrical conductivity was measured as a function of temperature by electrochemical impedance spectroscopy. It is established that (ZrO 2 ) 0.89 (Sc 2 O 3 ) 0.10 (Y 2 O 3 ) 0.01 crystals have the highest conductivity (0.168 S/cm at 1173 K).

We have studied the influence of the yttrium oxide (Y2O3) dopant (1 and 2 mol %) on the phase composition, structure, and electrical properties of ZrO2–9 mol % Sc2O3 solid solution. Stabilization of ZrO2 jointly with 9 mol % Sc2O3 and 2 mol % Y2O3 is shown to allow the acquisition of high phase stability transparent homogeneous crystals with a cubic structure. Their mechanical grinding is established to cause no change in the phase composition of these crystals, whereas the powders retain the initial fluorine structure. The powders preserved the original structure of the fluorite crystals. All the probed crystals reveal high microhardness and low fracture toughness. Increasing the Y2O3 concentration in the crystals led to a reduction of the maximum loads on the indenter, which the sample withstood without cracking. As is shown, the specific conductivity exhibits nonmonotonic behavior depending on the Y2O3 concentration in the crystals. Increasing the Y2O3 content to 2 mol % in the solid electrolyte reduces the conductivity of the crystals in the entire temperature range that is attributed to a decrease in the carrier mobility due to the increasing ion radius of the stabilizing ion.

Mo/Al/Mo/Au metallization scheme as an ohmic contact to undoped AlGaN/GaN heterostructures was investigated. The optimal thicknesses of the metal layers were determined: Mo (10 nm)/Al (60 nm)/ Mo (50 nm)/Au (50 nm). The specific contact resistance of the fabricated ohmic contact is 4.7 × 10–7 Ohm cm2 (0.14 Ohm mm). The microstructure of the contact after annealing was investigated using scanning and transmission electron microscopy, X-ray diffractometry and energy-dispersive X-ray spectroscopy. It is shown that a noticeable alloying of metallization into semiconductor upon annealing does not occur, but strong mixing of metals takes place. X-ray diffraction analysis demonstrated the presence of interfacial compounds, namely, Al2Au, Al3 + x Mo1–x , AlMo3, Al12Mo, GaMo3 and GaAu2. Investigations of the phase composition of films depending on the thickness ratio of the metallization layers have shown that the formation of Al2Au phase has a negative effect on the contact surface morphology, and the formation of GaMo3, Al x Moy phases likely plays the most important role in the ohmic contact formation, which was also confirmed by the method of energy-dispersive analysis.

The current study compares Al-Mn and Al-Mn-Mg alloys’ precipitation behavior in a temperature range of 350–450 °C. Mn-bearing nanodispersoids of the quasicrystalline-structured I-phase precipitate during the decomposition of supersaturated Al-based solid solution in both alloys. In the binary Al-Mn alloy, quasicrystalline-structured dispersoids precipitate only in the grain boundaries. The Mg addition does not change the dispersoids’ composition but significantly accelerates the precipitation kinetics. The Mg addition provides the precipitation of high-density distributed I-phase nanodispersoids in the body of the grains. The annealing temperature increase results in the I-phase transformation to a cubic α-phase, with both phases coexisting in the alloy structure.

Investigation of partially stabilized zirconium dioxide crystals via transmission electron microscopy has revealed a developed twin structure therein. The following compositions of the above crystals have been selected for this study: 97.2 mol % ZrO2–1.0 mol % Y2O3–1.8 mol % Yb2O3; 97.2 mol % ZrO2–2.0 mol % Y2O3–0.8 mol % Yb2O3; 97.2 mol % ZrO2–2.5 mol % Y2O3–0.3 mol % Yb2O3; and 96.3 mol % ZrO2–3.4 mol % Y2O3–0.3 mol % Yb2O3. X-ray diffraction analysis of these crystals indicate the presence of transformable (t) and nontransformable (t') tetragonal phases. Optical spectroscopy measurements of ZrO2–Y2O3–Yb2O3 crystals with tetragonal and cubic structures have highlighted in Yb3+-doped zirconium dioxide samples the formation of the optical centers of the Yb3+ ions is observed, whose crystal surrounding is similar to those in cubic zirconium dioxide crystals.

The age-hardenable Mg-4.7%Y-4.6%Gd-0.3%Zr (wt%) alloy has been studied after high pressure torsion (HPT) at room temperature, 200 °C and 300 °C. The formation of partially nanocrystalline structure upon HPT results in substantial strengthening relative to the undeformed state of the alloy. The research showed that the strength of the HPT processed alloy could be further improved by aging.

Crystals of (ZrO 2 ) 1− x (Sc 2 O 3 ) x solid solutions with x =0.035, 0.06, 0.09 and 0.11 have been grown for the first time using the directional crystallization technique. Analysis of the scandium distribution along the crystal showed that the composition of all specimens is homogeneous, and the Sc 2 O 3 concentration is almost identical to its content in the charge. All specimens exhibit a little decline in the scandium concentration along the crystal, this indicating that the effective distribution coefficient Sc is slightly greater than 1. The structure of as-grown crystals has been studied as a function of the Sc 2 O 3 stabilising oxide concentration by X-ray diffraction, transmission electron microscopy and Raman spectroscopy. Crystals containing 3.5 mol% Sc 2 O 3 are a mixture of the monoclinic and tetragonal phases, the crystals containing 6 mol% Sc 2 O 3 have a tetragonal structure, those with 9 mol% Sc 2 O 3 have the tetragonal phase with inclusions of the rhombohedral one and the specimens with 11 mol% Sc 2 O 3 represent the rhombohedral phase with inclusions of the cubic phase. The electrical conductivity was measured as a function of temperature by electrochemical impedance spectroscopy. The conductivity of the scandia stabilized crystals, in spite of their inhomogeneity, presence of stresses and low fracture toughness, is comparable with that of the yttria stabilized zirconia crystals.

The sequential chemical reduction of metals (copper or silver) and platinum was used to prepare M@Pt/C electrocatalysts that contain a high content of platinum on the surface of bimetallic nanoparticles. The compositions, microstructures and electrochemical behaviors of these electrocatalysts were studied using X-ray diffraction, thermogravimetry, X-ray fluorescence analysis, TEM and cyclic voltammetry. Depending on the composition and mode of synthesis, the obtained electrocatalysts have electrochemically active surface areas ranging from 35 to 61 m2 g−1 (Pt). The presence of nanoparticles with a core-shell structure was directly confirmed for Cu0.9Pt0.1@Pt/C sample. Copper-containing electrocatalysts exhibited better stability during voltammetric cycling compared to a similar composition of commercial Pt/C electrocatalyst and Ag0.9Pt0.1@Pt/C systems, but one of Ag0.9Pt0.1@Pt/C electrocatalysts has shown the highest specific activity in ORR.

The influence of treatment temperature and a carbon precursor on the formation of a Li4Ti5O12-based anodic material and its electrochemical characteristics as part of a lithium-ion battery have been investigated. It is demonstrated that the variation of annealing temperature and the addition of saccharose prior to final annealing allow for the variation of Li4Ti5O12 particle sizes. At annealing temperatures of 400–600°C, lithium titanate forms as part of an anatase titanium oxide composite. Thermogravimetry, Raman spectroscopy, and electrochemical testing results show that a preannealing of the sample at temperatures of no less than 400°C and the addition of saccharose with subsequent annealing in an inert atmosphere are required for the formation of a conducting carbon coating. The formation of the carbon coating facilitates the inclusion of the anatase phase into the charging and discharging processes, which significantly increases the electrochemical capacity of samples obtained at low annealing temperature. The highest electrochemical capacity values (140 mA h/g) of anodic Li4Ti5O12 samples were obtained only after annealing at 800°C. We note the unexpected formation of carbon nanotubes in samples with a final annealing temperatures of 600°C.

The property anisotropy in Bi2Se0.3Te2.7 alloy is analyzed by constructing index surfaces for the thermoelectric figure of merit and thermal expansion coefficient. Texture is an important factor forming the property anisotropy and technological applicability of an ingot for fabricating modules. The property anisotropy is analyzed based on studying the texture in ingots produced by the modified Bridgman method (thermoelectric plate growth in a flat cavity). Analysis of the texture shows that not only the crystallization rate, but also the crystallization cavity design is an important factor for the proposed crystallization method, affecting the formation of the thermoelectric-material structure. As the plate thickness is decreased by changing the heat removal conditions in a thin gap, a more perfect structure can be obtained.

(ZrO2)0.99-x(Sc2O3)x(Yb2O3)0.01 solid solutions crystals (x = 0.08–0.10) have been grown by directional crystallization of the melt in a cold crucible. Single-phase optically transparent single crystals were obtained only for the (ZrO2)0.90(Sc2O3)0.09(Yb2O3)0.01 composition. The phase composition, local structure and transport properties of the crystals have been studied using X-ray diffraction, Raman, optical and impedance spectroscopy. The dependence of the lattice parameters and the phase composition of (ZrO2)0.99-x(Sc2O3)x(Yb2O3)0.01 solid solutions on Sc2O3 content has been discussed. The (ZrO2)0.90(Sc2O3)0.09(Yb2O3)0.01 single-phase cubic single crystals had the maximum conductivity throughout the entire temperature range. It is shown that the high-temperature conductivity of the (ZrO2)0.90(Sc2O3)0.09(Yb2O3)0.01 single-phase cubic single crystals is close to the conductivity of the (ZrO2)0.90(Sc2O3)0.10 crystals. The results of studying the local structure of crystals by optical spectroscopy are presented.