V. P. Gorelov

Phase transitions in undoped BaCeO3

The linear thermal expansion (370–1500 K) and electrical conductivity (950–1220 K) have been measured for undoped BaCeO3 in dry air, pH2O=40 Pa. Samples were made both by conventional sintering and by solidification from inductive melting. Raman spectra were measured from 298 to 773 K. The obtained temperature dependencies, ΔL(T) and σ(T) upon heating and cooling, were treated mathematically by the method of differences (difference between experimental points and approximating the dependence by a first degree polynomial). This permitted to determine the position and the order of the structural phase transitions in BaCeO3. Five second-order transitions at 480±10, 530±10, 900±10, 1030±20 and 1170±20 K, and also one first-order transition at 665±10 K, were found. The transitions at 900 and 1030 K have not been reported before.

Preparation and Electrical Conductivity of BaZr1 – xRxO3 – α(R = Sc, Y, Ho, Dy, Gd, In)

The influence of process parameters on the density of BaZr0.9Y0.1O3proton-conducting ceramics was investigated. Dense ceramics (94–96% of theoretical density) were obtained by synthesis from coprecipitated zirconium and yttrium hydroxides and barium carbonate, followed by sintering at 1700°C. The conductivity of BaZr0.93R0.07O3 – α(R = Sc, Y, Ho, Dy, Gd, In) was measured as a function of temperature and oxygen partial pressure and was found to decrease in the order Y > Ho > Sc > Dy, In > Gd. In air, these materials are hole–ion conductors. At 800°C, BaZr0.93Y0.07O3 – αhas an ionic transference number of 0.16 and ionic conductivity of 3.6 × 10–4S/cm.

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.

Electroconductivity, Nature of Conduction, Thermodynamic Stability of the BaPr1 –xYxO3 – αCeramics

AbstractThe electroconductivity and the nature of conduction of vacuum-dense ceramics BaPr1 – xYxO3 – α(x= 0.05–0.15) is studied at temperatures of 373 to 985°C,

Total and hole conductivity in the BaZr1 − xYxO3 − α system (x = 0.02−0.20) in oxidizing atmosphere

P_{0_2}

Effect of scandium sublattice defectiveness on ion and hole transfer in LaScO3-based proton-conducting oxides

of 2.1 × 104to 10–11Pa, and

Synthesis and properties of high-density protonic solid electrolyte BaZr0.9Y0.1O3 − α

P_{{\text{H}}_2 0}