Structural and Transport Properties of La2/3 – x Li3x □4/3 – 2x Ta2O6 Perovskite-Like Solid Solutions

The homogeneity range of La_2/3–x Li_{3x 4/3 – 2x} Ta₂O₆ perovskite-like solid solutions was determined. The transport properties of the La_2/3–x Li_{3x 4/3 – 2x} Ta₂O₆ oxides were shown to correlate with their lattice parameters and composition. Lithium-doped lanthanum metatantalate with an orthorhombically distorted perovskite-like structure is a good solid electrolyte with high lithium ion conductivity.     

Synthesis and Properties of La2(Mo1 – x M x )2O9 (M = Nb, Ta) Ionic Conductors

La₂(Mo_{1 – x} M _x )₂O₉ (M = Nb, Ta; 0 < x 0.2) solid solutions were prepared, and their physicochemical and electrical properties were studied. Second harmonic generation measurements indicate that the solid solutions have a noncentrosymmetric structure and undergo a structural phase transition accompanied by a sharp increase in ionic conductivity, similar to that of La₂Mo₂O₉. The transition temperature is found to decrease with increasing Nb or Ta content. The introduction of 5 wt % Nb increases the 800°C conductivity of the material.     

Synthesis and Photoelectrochemical Properties of Cd4 – x Hg x GeS6 Solid Solutions

Cd₄GeS₆, Hg₄GeS₆, and Cd_{4 – x} Hg _x GeS₆ crystals are grown from presynthesized charges. The electrochemical and photoelectrochemical properties of a Cd_1.2Hg_2.8GeS₆ electrode are studied. The energy positions of the conduction-band and valence-band edges are compared for two samples having identical cation compositions but differing in anion composition.     

Effect of Gamma Irradiation on the Piezoelectric Properties of K2Sr4Nb10O30–K6Li4Nb10O30 Solid Solutions

The effect of gamma irradiation on the dielectric ( ₃₃/₀, tan) and piezoelectric (d ₃₁, g ₃₁, K _p, Q _m) properties of ₂Sr₄Nb₁₀O₃₀–K₆Li₄Nb₁₀O₃₀ solid solutions (tetragonal tungsten bronze structure) was studied as a function of K₆Li₄Nb₁₀O₃₀ content. The results demonstrate that increasing the gamma dose to 9 × 10⁵ Gy reduces ₃₃/₀ and tan. With increasing Li⁺ content (filling of triangular channels), d ₃₁, g ₃₁, K _p, and Q _m increase. The results are interpreted in terms of the generation of stable defects and effective redistribution of the energy of gamma radiation over the ceramic sample.     

Synthesis and Properties of (Sr1 – xMx)2Nb2O7 (M = Cu, Ni) Solid Solutions

(Sr_{1 – x} M _x )₂Nb₂O₇ (M = Cu, Ni) layered perovskite solid solutions were synthesized, and their stoichiometry ranges were determined. The electrical properties of the solid solutions were compared with those of Sr₂Nb₂O₇.     

Properties of Nd1 – x Gd x CoO3 Solid Solutions

NdCoO₃, GdCoO₃, and Nd_{1 – x} Gd _x CoO₃ solid solutions with x= 0.1–0.9 are prepared by solid-state reactions, their lattice parameters are determined, and their electrical conductivity and thermal expansion are measured between 300 and 1110 K in air. All of the solid solutions are found to have an orthorhombically distorted perovskite structure and to exhibit anomalies in conductivity and thermal expansion, due to a semiconductor–metal transition.     

Synthesis and Physicochemical Properties of Crystalline and Glassy La14 – x – y Gd x Eu y (BO3 )6(GeO4)2O8 Solid Solutions

Using solid-state reactions, La_{14 – x – y} Gd _x Eu _y (BO₃)₆(GeO₄)₂O₈ solid solutions isostructural with Ln₁₄(BO₃)₆(GeO₄)₂O₈ (Ln = Pr, Nd, Sm, Eu, Gd) were prepared for the first time, and their melting points and melting behavior were established. Liquid quenching of the solid solutions was found to yield thermally stable glasses containing as much as 60 mol % rare-earth oxides. The composition limits of the glass-forming region were determined, and the luminescence spectra of both crystalline and glassy solid solutions were studied.     

Structure and Properties of Nonstoichiometric La1 – x Na x MnO3 ± γ Solid Solutions

The structural, electrical, magnetic, and magnetoresistive properties of polycrystalline La_{1 – x} Na _x MnO_{3 ±} are studied in the range 0.08 x 0.16. The solid solutions contain La and O vacancies and crystallize in the space group R3¯c. The Curie temperature of the solid solutions depends not only on the formal charge state of Mn but also on the Na content, the amounts of La and O vacancies, and synthesis conditions. The synthesized materials are potentially attractive as room-temperature magnetic sensors.     

Preparation and Properties of CuCr1 – x V x Se2 Solid Solutions

The phase relations in the CuSe–(1 – x)CrSe–xVSe system were studied. The system was found to contain CuCr_{1 – x} V _x Se₂ solid solutions isostructural with CuCrSe₂. The solid-solution range and oxidation states of Cr and V were determined.     

Structural Phase Transitions of High-Pressure Li x Na1 – x NbO3 Solid Solutions

Li _x Na_{1 – x} NbO₃ (x = 0.125, 0.17, 0.25) solid solutions are synthesized at high pressures (6 GPa) and temperatures (1100–1500°C), and their polymorphic transformations are studied by x-ray diffraction. The composition and temperature dependences of lattice parameters for the identified polymorphs are presented. The results demonstrate that the high-pressure solid solutions with x = 0.17 and 0.25 are supersaturated under ordinary conditions. Heating these solid solutions to above 800°C leads to precipitation of an LiNbO₃-based phase.     

Preparation and Magnetic Properties of CuCr1 – x Mn x S2 Solid Solutions

Phase relations in the CuS–CrS–MnS system (20 mol % MnS) were studied. The system was found to contain CuCr_{1 – x} Mn _x S₂ solid solutions isostructural with CuCrS₂. The solid-solution range and the oxidation states of Cr and Mn were determined.     

Crystal Growth and Properties of Cd1 – x Zn x As2 Solid Solutions

Cd_{1 – x} Zn _x As₂ (x = 0.03, 0.05, 0.06) single crystals are grown by the Bridgman method, and their optical absorption spectra are measured. The introduction of Zn is shown to increase the band gap of CdAs₂, by up to 14 meV at x = 0.06. The highest content of ZnAs₂ incorporated into CdAs₂ is 6 mol %.     

Synthesis of ZnFe2O4–Zn2ZrO4Solid Solutions

Low-temperature plasma synthesis was used to prepare solid solutions ( and ) in the ZnFe₂O₄–Zn₂ZrO₄pseudobinary system. The Zn_{2 – x} Zr_{1 – x} Fe_2x O₄solid solutions were found to have a tetragonal spinel structure (a= 8.607–8.740 Å, c= 8.798–9.120 Å) in the composition range x= 0–0.55 and a cubic spinel structure (a= 8.447–8.539 Å) at x= 0.75–1.0. The tetragonal lattice distortion is attributed to a pseudo-Jahn–Teller effect. The electrical conductivity of the solid solutions shows semiconducting behavior and rises by a few orders of magnitude with increasing Fe³⁺content.     

Physical Properties of NaNbO3–A2+TiO3and NaNbO3–A2+Nb2O6Solid Solutions

Solid solutions of compounds with the ilmenite, columbite, or potassium tungsten bronze structure in the perovskite compound NaNbO₃were studied. The observed property–structure–composition relations were used to choose promising compositions for designing new piezoelectric ceramics.     

Microstructure Effects on the Superconducting Properties of YBa2Cu3 – x M x O7 – δ (M = Ag, Hg)

The properties of YBa₂Cu_{3 – x} Ag _x O_{7 –} and YBa₂Cu_{3 – x} Hg _x O_{7 –} (0 < x 0.5) solid solutions were studied. The solute concentration is shown to have a significant effect on the superconducting transition temperature, density, and grain size of the solid solutions. The difference in the composition dependences of the properties of the solid solutions is interpreted in terms of the crystal-chemical behavior of the Ag and Hg ions.     

Molecular Dynamics Simulations of Li x Mn2O4 Spinel Solid Solutions with Simple Potential Models

Molecular dynamics simulations of Li _x Mn₂O₄ (0 < x 1) spinel solid solutions were carried out with the use of simple pair potentials available in the literature. The results demonstrate that computer simulations using the existing potentials with an exponential repulsion term fail to adequately reproduce appreciable Li⁺ mobility in a stable (near-zero mobility of the manganese and oxygen ions) crystalline phase. Lennard-Jones potentials make it possible to simulate such a phase at high temperatures (on the order of 1000 K).     

Effects of Chemical Composition and Sintering Temperature on the Structure of La1 – x Sr x MnO3 ± γ Solid Solutions

The structural parameters of La_{1 – x} Sr _x MnO_{3 ±} solid solutions sintered at different temperatures are refined using chemical analysis, x-ray fluorescence, and Rietveld profile analysis data. The samples are shown to consist of two rhombohedrally distorted perovskite phases (sp. gr. R c and R3m) identical in chemical composition and containing excess oxygen. The electrical properties and magnetoresistive response of the Sr-doped lanthanum manganite ceramics depend on the relative amounts of these phases. The origin of structural disordering in the materials studied is discussed.     

Mechanochemical Synthesis and Electrical Conductivity of Bi1.6M0.4O3 – x (M = Ca, Ca0.5Sr0.5 , In, Y, La) Metastable Fluorite Solid Solutions

Metastable fluorite solid solutions with the nominal composition Bi_1.6Mo_0.4O_{3 – x} (M = Ca, Ca_0.5Sr_0.5, In, Y, La) are prepared by mechanochemical synthesis, and their structure is studied by x-ray diffraction. The oxygen ion conductivity of dense samples prepared by hot pressing is measured in air.     

Electrical Properties of Cd x Zn1 – x As2 Solid Solutions at Pressures of up to 9 GPa

The electrical properties of n-type Cd_0.97Zn_0.03As₂ and Cd_0.95Zn_0.05As₂ single crystals are studied at hydrostatic pressures of up to 9 GPa. With increasing pressure, the carrier concentration in the solid solutions increases by more than three orders of magnitude, while their electrical resistivity drops by more than four orders of magnitude. In contrast to CdAs₂, the pressure dependences of resistivity for the solid solutions show no anomalies, which is interpreted as evidence that Zn consolidates the structure of CdAs₂, occupying vacant As sites.     

Mössbauer Study of Tetragonal ZrO2–Y2O3–Fe2O3 Solid Solutions

Tetragonal Zr_0.886Y_0.057Fe_0.057O_{2 –} solid solutions prepared by calcining coprecipitated and successively precipitated hydroxide mixtures were studied by Mössbauer spectroscopy immediately after calcination and after long-term storage. The results indicate that the solid solutions prepared via coprecipitation and successive precipitation contain Fe³⁺ in two (octahedral coordination) and three (octahedral, fivefold, and tetrahedral coordinations) inequivalent sites, respectively. Partial Fe³⁺ substitution for Y³⁺ is shown to prevent or substantially slow down the low-temperature structural degradation of stabilized zirconia.