S. V. Plaksin

Electrical conductivity of CaZr1 − x (x = 0.01–0.20) in dry and humid air

The total conductivity of CaZr1 − xScxO3 − α (x = 0.01–0.20) materials has been measured by the four-probe dc method at temperatures from 600 to 900°C in humid air (pH2O = 40–2500 Pa), and CaZr0.95Sc0.05O3 − α has been characterized by impedance measurements. The ion and proton transport numbers in CaZr0.95Sc0.05O3 − α have been determined as functions of air humidity. The observed anomalies in the temperature dependences of electrical conductivity for the materials studied have been compared to dilatometry data and interpreted in terms of structural changes in their oxygen sublattice.

Effect of the synthesis technique on the physicochemical properties of Ce0.8(Sm0.75Sr0.2Ba0.05)0.2O2 − δ

A multicomponent solid electrolyte of composition Ce0.8(Sm0.75Sr0.2Ba0.05)0.2O2 − δ has been synthesized by three different techniques: solid-state reaction, laser evaporation, and the glycine nitrate process. Its microstructure, sintering kinetics, and electrical properties have been studied in relation to the synthesis technique. Ceramics produced using laser evaporation consisted of submicron (0.2 μm) grains and offered the highest electrical conductivity: 27 × 10−3 S/cm at 873 K.

Ionic conductivity of Li 8 − 2 x Sr x ZrO 6

Li8 − 2xSrxZrO6 solid solutions have been synthesized, and their transport properties (electronic conductivity, temperature and composition dependences of their conductivity, and activation energy for conduction) have been studied using impedance spectroscopy. The results demonstrate that partial strontium substitution for lithium increases the conductivity of the materials relative to undoped Li8ZrO6.

Synthesis and electrochemical properties of Li8 − xZr1 − xNbxO6 solid solutions

New lithium-conducting solid solutions based on lithium orthozirconate have been synthesized by mutual doping of the related structures Li8ZrO6 and Li7NbO6. The main factor determining the increase in the electrical conductivity of the Li8 − xZr1 − xNbxO6 solid solutions is the formation of lithium vacancies in the tetrahedral and octahedral layers. The practical stability of the Li8 − xZr1 − xNbxO6 ceramics to metallic lithium has been studied.

Preparation and Physicochemical Properties of Praseodymium Oxide Films and Ceramics

A praseodymium oxide film has been produced by dip-coating an alundum (Al2O3) substrate in an ethanolic solution of praseodymium nitrate, followed by heat treatment, and ceramic praseodymium oxide samples have been prepared for comparison. The materials have been characterized by simultaneous thermal analysis (STA), X-ray diffraction, scanning electron microscopy, and dilatometry. The electrical conductivity of the films and ceramic samples has been measured as a function of temperature by a standard fourprobe dc technique at different air humidities. Phase transitions of the samples have been detected by STA, dilatometry, and electrical conductivity measurements.

Oxygen isotope exchange in the LSM-YSZ composite under the conditions of long-term tests

The stability of the properties of the composite 40 vol % La0.6Sr0.4MnO3 − δ-60 vol % Zr0.83Y0.17O1.92 (LSM-YSZ) held for 1000 h at a temperature of 800°C and an oxygen pressure of 1.01 kPa and changes in its microstructure were studied by isotope exchange and gas-phase analysis. The oxygen exchange was found to occur by the dissociative adsorption mechanism involving the adsorption forms of oxygen on the triple-phase LSM-YSZ-O2 boundary. The rate-determining step of the oxygen exchange of the composite did not change with time. The rate of oxygen exchange decreased by 22%, which is comparable to the decrease in the length of the LSM-YSZ-O2 triple-phase boundary (∼20%), on which oxygen exchange is dominant. The conductivity of the LSM-YSZ composite increased due to the connectivity of the material.

Electrochemical properties of solid solutions in the Li8Zr1 − xCexO6 system

Li8Zr1 − xCexO6 solid solutions based on lithium zirconate Li8ZrO6 were obtained by solid-state synthesis in an inert atmosphere. Their transport properties (the electron component of the total conductivity, the temperature and concentration dependences of conductivity, and the activation energies) were studied by impedance spectroscopy. The practical stability of the ceramic samples of Li8Zr1 − xCexO6 solid solutions (x = 0–0.07) at 473–573 K against melted lithium was studied.

Synthesis and Phase Composition of NaxMxTi8 – xO16(0.67 ≤ x≤ 2.0; M = Al, Ga, In)

The phase composition of NaxMxTi8 – xO16(M = Al, Ga, In) materials was studied by x-ray diffraction. In the Al system, a hollandite phase was obtained in the composition range 0.67 ≤ x≤ 2.0. The results are interpreted in terms of Goldschmidts tolerance factor. It is shown that A2B8O16compounds with the hollandite or NaxTiO2-type structure are more difficult to prepare at smaller ionic radii of M. The assumption is made that the monoclinic NaxTiO2-type phase may, under certain conditions, have a channel structure.