New Solid Solution and Phase Equilibria in the Subsolidus Area of the Three-Component CuO–V2O5–Ta2O5 Oxide System

The results of the study of the three-component system of CuO–V2O5–Ta2O5 oxides showed, inter alia, that in the air atmosphere in one of its cross-sections, i.e., in the CuV2O6–CuTa2O6 system, a new substitutional solid solution with the general formula CuTa2−xVxO6 and homogeneity range for x > 0.0 and x ≤ 0.3 is formed. The influence of the degree of incorporation of V5+ ions into the CuTa2O6 crystal lattice in place of Ta5+ ions on the unit cell volume, thermal stability and IR spectra of the obtained solid solution was determined. Moreover, the value of the band gap energy of the CuTa2−xVxO6 solid solution was estimated in the range of 0.0 < x ≤ 0.3, and on this basis, the new solid solution was classified as a semiconductor. On the basis of the research results, the studied system of CuO–V2O5–Ta2O5 oxides was also divided into 12 subsidiary subsystems.

Modelling of shear stress field in glide plane in substitutional solid solutions

The formation of stochastic shear stress field in the glide plane in the substitutional solid solution was investigated by computer simulation. If the atoms in the crystal lattice nodes of the substitutional solid solution are considered as a kind of point defects in the virtual solvent medium, the shear stress distribution in the glide plane can be calculated based on the interaction of edge dislocation and such defects. For concentrated solid solutions, the shear stress will be a normally distributed random value with zero mathematical expectation. The standard deviation of this distribution will be the greater the greater the effective distortion of crystalline lattice of the alloy. In the case of dilute solid solution, where one of the components has a predominant content, the simulation gives shear stress distribution in the glide plane, where large peaks are separated from each other by wide areas of near-zero stresses. Thus, there are separate discrete obstacles in the form of large stress peaks for the edge dislocation in the glide plane in dilute solid solution, and the space between the peaks is practically stress-free. The average distance between large peaks correlates with the average distance between the atoms of those components that are few in solution, if total atomic fraction of these components is considered. Thus, the proposed modeling gives a very realistic shear stress distribution in the glide plane for concentrated and dilute substitutional solid solutions with fcc and bcc structures. This can be useful in further modeling the yield strength in multicomponent alloys. Keywords: dislocation, distorsion, shear stresses.

Modeling of structural and energetic parameters of р-Er1-xScxNiSb semiconductor

The energy expediency of the existence of Er1-xScxNiSb substitutional solid solution up to the concentration x≈0.10 was established by modeling the variation of free energy ΔG(x) values (Helmholtz potential). At higher Sc concentrations, x> 0.10, there is stratification (spinoidal decomposition of phase). It is shown that in the structure of p-ErNiSb semiconductor there are vacancies in positions 4a and 4c of Er and Ni atoms, respectively, generating structural defects of acceptor nature. The number of vacancies in position 4a is twice less than in position 4c. This ratio also remains for p-Er1-xScxNiSb. Doping of p-ErNiSb semiconductor by Sc atoms by substitution of Er atoms is also accompanied by the occupation of vacancies in position 4a. In this case, Ni atoms occupy vacancies in position 4c, which can be accompanied by the process of ordering the p-Er1-xScxNiSb structure. Occupation of vacancies by Sc and Ni atoms leads to an increase of the concentration of free electrons, an enlarge of the compensation degree of semiconductor, which changes the position of the Fermi level εF and the mechanisms of electrical conductivity.

Formation of Cd x Pb1− x S/Cd1- δ S Thin-Film Two-Phase Compositions by Chemical Bath Deposition: Composition, Structure, and Optical Properties

The possibility of forming thin-film two-phase compositions CdxPb1-xS/Cd1-dS by using the chemical bath deposition from aqueous media with adding various cadmium salts has been demonstrated. The crystal structure, chemical composition, morphology, and the band gap were studied by the X-ray diffraction, scanning electron microscopy, elemental analysis, Auger and Raman spectroscopy, and diffuse reflectance measurements. The formation of a CdxPb1-xS/Cd1-dS substitutional solid solution phase in well-faceted crystallites on the substrate of an X-ray amorphous CdS phase has been experimentally proved. The found differences in their composition are the result of the effect of the nucleophilicity of the anionic component of the cadmium salt on the kinetics of thiourea decomposition. The results demonstrate the possibility of forming thin-film two-phase compositions or heterostructures on the base of cadmium and lead sulfides in one technological stage by using chemical bath deposition, which can be important for the creation of solar cells.

Microstructure and Photothermal Conversion Performance of Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 Selective Absorbing Film for Non-Vacuum High-Temperature Applications

This paper aims to clarify the phase composition in each sub-layer of tandem absorber TiMoAlON film and verify its thermal stability. The deposited multilayer Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 films include an infrared reflectance layer, light interference absorptive layers with different metal doping amounts, and an anti-reflectance layer. The layer thicknesses of Ti, Mo-TiAlN, Mo-TiAlON, and Al2O3 are 100, 300, 200, and 80 nm, respectively. Al content increases to 12 at.% and the ratio of N/O is nearly 0.1, which means nitride continuously changes to oxide. According to X-ray Diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results, the diffraction peak that appears at 2θ = 40° demonstrates that Mo element aggregates in the substitutional solid solution (Ti,Al)(O,N) columnar grain. TiMoAlON films have low reflectivity in the spectrum range of 300–900 nm. When Al content is more than 10 at.%, absorptivity is almost in the spectrum range from visible to infrared, but absorptivity decreases in the ultraviolet spectrum range. When Al content is increased to 12 at.%, absorptivity α decreases by 0.05 in the experimental conditions. After baking in atmosphere at 500 °C for 8 h, the film has the highest absorptivity when doped with 2 at.% Mo. In the visible-light range, α = 0.97, and in the whole ultraviolet-visible-light near-infrared spectrum range, α = 0.94, and emissivity ε = 0.02 at room temperature and ε = 0.10 at 500 °C.

Influence of hydrogenation conditions on the structural, optical, and magnetic properties of degenerated Ni/Al co-doped anatase nanocomposite

In the present work, pristine and Ni2+/Al3+- codoped anatase (TiO2) nanocomposite powders were synthesized by the thermal co-precipitation method. The samples were characterized by several techniques. The X‐Ray diffraction (XRD) was used for structural characterization and the optical absorption spectroscopy was used for the optical characterization. The structural/optical studies proved the formation of a substitutional solid solution (SSS). The magnetization measurements were performed to investigate the magnetic properties of the synthesized samples. In the present work, nickel (Ni2+) dopant ions were used to introduce stable ferromagnetic (FM) properties into the synthesized anatase, while Al3+ dopant ions were utilized to supply itinerant electrons necessary to support and boost the created FM properties. The roadmap of the present work was to establish the hydrogenation conditions necessary to create ferromagnetic (FM) properties in the host codoped samples and study the effect of hydrogenation temperature on the parameters of the created FM properties, especially the magnetic energy (Umag) and saturation magnetization (Msat). It was found that the created FM properties in Ni/Al-doped TiO2 nanocomposite powder by using the hydrogenation effect could be enhanced and controlled via the temperature of the hydrogenation (TH). The experimental results revealed that Umag of TiO2:Ni:Al system increased by ~241% and the saturation magnetization by ~140% with increasing of TH by 100 oC (from 400 oC to 500oC). The obtained saturation magnetization (Msat) of 1.09 emu/g and magnetic energy (Umag) of 42.6 erg/g were higher than the previously obtained values for created Ni-doped TiO2 by ~50 times. Such great novel results were obtained due to dealing with two factors; the Al3+ ions as co-dopant, which can supply an excess of itinerant electrons that boost the S.S Heisenberg interactions in addition to choosing a suitable temperature of hydrogenation.

Fine control over the structure and morphology of metal-matrix composites employing submicron oxide particles with the adjustable redox-activity

It is shown that copolycondensation of mixed vanadic and molybdic acids under the solvothermal conditions yields substitutional solid solution V2O5 : MoO3 (isostructural to V2O5 xerogel) the redox activity of which exhibits increase with the MoO3 content. Thus obtained mixed oxide 0.5V2O5 : 0.5MoO3 with high redox activity, being codeposited with the galvanic nickel, ensure multicenter nucleation of metal phase, yields compact composite with the enhanced corrosion stability.

Charge Transport Mechanism in p--Si--n--(Si2)1--x(CdS)x Semiconductor Structures

The paper shows that it is possible to use liquid phase epitaxy to obtain single-crystal substitutional solid solution p--Si--n--(Si2)1--x(CdS)x (0 ≤ x ≤ 0,01) on silicon substrates from Sn--Si--CdS solution melt in a palladium-purified hydrogen atmosphere. The manufacturing conditions resulting in perfect epitaxial layers with mirror surfaces exhibiting the best parameters are as follows: crystallization start temperature of 1100 °С; forced cooling rate of 1 degree/min. The epitaxial films obtained feature a thickness of 20 µm and the n conductivity type, specific resistances being 0.018 Ω·cm. Investigation results concerning charge transfer mechanisms in p--Si--n--(Si2)1--x(CdS)x structures at room temperatures show that the forward current--voltage characteristic consists of several characteristic segments, and there are various mechanisms that drive charge transfer processes. At low current densities, the increase in current is due to growing concentration of injected carriers on account of simple local centres; at high densities, it is due to recombination processes in compound complexes inside which electron exchange takes place. This fact is what proves that the structure under consideration displays better rectifying properties with increasing voltage. We determined that these epitaxial films of (Si2)1--x(CdS)x (0 ≤ х ≤ 0,01) solid solutions are promising materials for high-current rectifier diodes

Synchronously Improved Voltage Gradient and Mechanical Properties of ZnO Based Varistor by Doping Ga2O3

ZnO based varistors with high voltage gradient and excellent mechanical and thermal properties were fabricated by Ga2O3 doping and using nanoparticles. The compositions and microstructure of the varistors, as well as their electrical, mechanical and thermal properties were investigated by XRD, XPS, SEM, E-J, C-V, mechanical and thermal expansion measurements. Also, the mechanism of Ga2O3 addition on electrical and mechanical properties of the varistors was discussed detailedly. Results showed that the added Ga2O3 preferentially occupied the lattice position of ZnO crystal through the formation of a substitutional solid solution (Donor doping), they then occupied the void position through the formation of an interstitial solid solution (Acceptor doping), in which residual Ga2O3 existed in the grain boundary and served as inversion boundaries. The formation of the substitutional and interstitial solid solutions helped to improve the electrical properties, when the Ga2O3 content was 0.40 mol%, E1mA, α and K were 1235.00 V·mm− 1, 46.0 and 1.37, respectively, being due to the small particle size and the relative content of donor, acceptor and grain boundary in ZnO grain; The increased content of inversion boundaries stimulated the abnormal growth of ZnO grain, and the formed plate-like grain helped to improve the mechanical properties and thermal expansion coefficient of the varistors, values of σf, Ef, and KIC reached 147.43 MPa, 213.61 GPa and 2.05 MPa·m1/2, showing improvements of 25.29%, 47.67%, and 38.51%, respectively, compared with those of ZnO varistors without Ga2O3.

Crystal Chemistry of an Erythrite-Köttigite Solid Solution (Co3–xZnx) (AsO4)2·8H2O

A wide compositional range, covering about 90% of an expected erythrite-köttigite substitutional solid solution with extreme compositions of (Co2.84Mg0.14Zn0.02) (AsO4)2·8H2O and (Zn2.74Co0.27) (AsO4)2·8H2O, was revealed in a suite of samples from a polymetallic ore deposit in Miedzianka, SW Poland. Members of the solid solution series were examined by means of Electron Probe Microanalysis (EPMA), Scanning Electron Microscopy (SEM)/Energy-Dispersive Spectrometer (EDS), X-ray single-crystal and powder diffraction, and Raman spectroscopy. Metal cations were randomly distributed between two special octahedral sites in the erythrite–köttigite structure. In response to Co ↔ Zn substitutions, small but significant changes in bond distances (particularly in [AsO4] tetrahedra), rotation, and distortion of co-ordination polyhedra were observed. Two sub-series of dominant cationic substitutions (Co-Mg-Ni and Co-Fe-Zn) were noted within the arsenate series of vivianite-group minerals linked by erythrite. The paragenetic sequence erythrite → Zn-rich erythrite → Co-rich köttigite → köttigite reflects the evolution of the solution’s pH towards increased acidity and a relative increase in the concentration of Zn ions following precipitation of erythrite.