B. D. Antonov

Synthesis and Electrical Properties of Lithium Metazirconate

Lithium metazirconate Li2ZrO3 with a monoclinic lattice is synthesized; the lattice parameters are: a = 0.5432 nm, b = 0.5427 nm, c = 0.903 nm, γ = 112.72°, and Z = 4. The conductivity of both the stoichiometric compound and samples rich or deficient in Li2O near this composition is determined. The conductivity of the synthesized compound reaches 0.029 S cm–1 at 600°C. The activation energy for the high-temperature segment is 13.8 kJ mol–1. An abnormal behavior (abrupt jump) of the temperature dependence of the conductivity at 430°C is discovered and attributed to a phase transition. The change in the structure in this temperature domain (400 to 500°C) is corroborated by the high-temperature X-ray analysis.

Structure and electric properties of BaCe0.77 − xZrxGd0.2Cu0.03O3 − δ

AbsractIn the present work, samples with the composition of BaCe0.77 − xZrxGd0.2Cu0.03O3 − δ (x = 0, 0.1…0.7, 0.77) were synthesized according to the standard solid state technique. The effect of zirconium oxide on the phase character, structure, and conductivity was studied using the methods of X-ray diffraction analysis, scanning electron microscopy, and four-probe method, accordingly. Stability of these materials in the flow of carbon dioxide was studied. The results show that introduction of zirconium oxide leads to preservation of a single-phase system (x ≤ 0.6), a decrease in the grain size, and an increase in stability in the CO2 atmosphere.

Specific features of the interaction of α- and γ-modifications of Al2O3 with carbonate and carbonate-chloride melts

Data on reactivities of α- and γ-Al2O3 finely dispersed powders in a melted carbonate eutectic (Li2CO3–Na2CO3–K2CO3)eut and carbonate-chloride mixture 0.72(Li2CO3–Na2CO3–K2CO3)eut–0.28NaCl were obtained. The methods of synchronous thermal and X-ray phase analyses and Raman spectroscopy confirmed that, in contrast to γ-Al2O3, α-Al2O3 does not chemically interact with the melted carbonate eutectic and carbonate-chloride mixture (Li2CO3–Na2CO3–K2CO3)eut–NaCl can be recommended as a thickening agent for a carbonate fuel cell.

Effect of alloying with palladium on the electrical and mechanical properties of copper

Structure and physicomechanical properties of Cu–Pd alloys that contain 0.5–5.9 at % Pd have been studied. It has been shown that, in all alloys, a solid solution is formed; the lattice parameter of the fcc lattice and the electrical resistivity of the alloys grow linearly with an increase in the content of palladium. It has also been revealed that the introduction of palladium leads to an increase in the recrystallization temperature and to an increase in the strength properties. The assumption on the formation of an atomic short-range order in the quenched Cu–4.6 at %Pd and Cu–5.9 at %Pd alloys has been made.

Electrotransfer in nonstoichiometric lanthanum scandate LaSc1 − xO3 − α (x = 0−0.1)

The phase composition and the total and partial conductivities of ceramic samples LaSc1 − xO3 − α (x = 0−0.1) are studied as a function of the air humidity (pH2O = 0.04−2.35 kPa) and the oxygen partial pressure (−15 ≤ logpO2 ≤ −0.68) in a wide temperature range from 100 to 900°C as well as their thermal expansion.

Electrical conductivity of LaCoxFe1 − xO3 − δ and LaLi0.1CoxFe0.9 − xO3 − δ (0 ≤ x ≤ 0.4) oxides

We have studied the effect of Co and Li concentrations on the phase composition and electrical conductivity of LaCoxFe1 − xO3 − δ and LaLi0.1CoxFe0.9 − xO3 − δ perovskite-like oxides synthesized in air at 1470 K. Single-phase materials with an orthorhombic crystal structure were obtained in the range 0 ≤ x ≤ 0.3. The composition dependences of conductivity have a minimum at xc = 0.1 and 0.2, respectively. In the range x > 0.1, the conductivity of LaCoxFe1 − xO3 − δ increases with increasing Co concentration for T > 700 K and decreases for T < 600 K. The conductivity of La(Li0.1CoxFe0.9 − x)O3 − δ in the range 0 ≤ x ≤ 0.1 and for x ≥ 0.2 increases with Co concentration throughout the temperature range studied.

Rubidium ion conducting Rb2 − 2xAl2 − xAxO4 (A = Nb, Ta) solid electrolytes

Rb2 − 2xAl2 − xAxO4 (A = Nb, Ta) solid solutions have been synthesized, and their conductivity has been measured as a function of temperature and composition. The highest rubidium ion conductivity in the Rb2 − 2xAl2 − xAxO4 solid solutions is 3.16 × 10−3 S/cm at 300°C and ∼ 2 × 10−2 S/cm at 700°C. The high rubidium ion conductivity of the synthesized solid electrolytes is mainly due to the formation of rubidium vacancies when Nb5+ or Ta5+ substitutes for Al3+ and to the specific features of the crystal structure of RbAlO2.

Production, structure, texture, and mechanical properties of severely deformed magnesium

Methods of the severe plastic deformation (SPD) of pure magnesium at room temperature, namely, transverse extrusion and hydroextrusion in a self-destroyed shell, have been developed. The maximum true strain of the samples after the hydroextrusion was e ~ 3.2; in the course of transverse extrusion and subsequent cold rolling, a true strain of e ~ 6.0 was achieved. The structure and mechanical properties of the magnesium samples have been studied in different structural states. It has been shown that the SPD led to a decrease in the grain size d to ~2 μm; the relative elongation at fracture δ increased to ~20%. No active twinning has been revealed. The reasons for the high plasticity of magnesium after SPD according to the deformation modes suggested are discussed from the viewpoint of the hierarchy of the observed structural states.

Formation of an ordered structure in the Cu-49 at % Pd alloy

We compare the kinetics of the formation of an ordered structure in the Cu-49 at % Pd alloy in various initial states and demonstrate that the alloy can be brought into a single-phase, B2-ordered state, at variance with the commonly accepted Cu-Pd phase diagram. The alloy in this structural state has an extremely low resistivity: ρ = 5.48 × 10−8 Ω m.

Conductivity of potassium-cationic solid electrolytes in the K0.85Pb0.075(Fe1 − xAlx)O2 system

New potassium-conducting solid electrolytes in the mixed ferrite-aluminate system K0.85Pb0.075(Fe1 − xAlx)O2 are synthesized and studied. The electrolytes exhibit high ionic conductivity in the studied temperature range of 350 to 750°C (approximately 10−2 S/cm at 400°C and approximately 10−1 S/cm at 700°C). An increase in the conductivity with increasing concentration of iron in the specimens is a general tendency. However, in a wide range of compositions (from x = 0.2 to x = 0.9), the conductivity only slightly depends on x. Possible reasons for the effect of Fe/Al ratio in the structure of solid electrolytes on their transport properties are discussed.