Affiliation:
1. Institute of High-Temperature Electrochemistry, Ural Branch, Russian Academy of Science
2. Ural Federal University named after the first President of Russia B.N. Eltsin
Abstract
The paper is devoted to the study of the conduction mechanism in perovskite phases with composition La2Me+3ZnO5.5 (Me+3 = Al3+, Sc3+, In3+). The phases were synthesized by a standard ceramic technique in the 700–1300°C temperature range. The structure of the La2InZnO5.5 and La2ScZnO5.5 samples is orthorhombic, while the La2AlZnO5.5 sample crystallizes in the cubic symmetry. The electrical conductivity of La2Me+3ZnO5.5 (Me+3 = Al3+, Sc3+, In3+) samples is studied as a function of temperature (200–900°C), oxygen partial pressure pO2, and humidity pH2O. The complex oxides are found to have a mixed type of conduction in air, the electronic contribution (the p-type conduction) increases with increasing temperature. The phases exhibit the dominant oxygen-ion transport at temperatures below 500°C. In wet atmosphere, Sc3+- and In3+-containing samples are capable of incorporating water from gas phase and forming proton defects. No significant proton transport in the La2AlZnO5.5 sample is realized. The partial conductivities σH+, σO2−, σh in a wide range of temperatures and рО2 are discussed.
Publisher
The Russian Academy of Sciences