Ionic (O2- and H+) Transport in Oxygen-Deficient Perovskites La2Me+3ZnO5.5

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 degrees 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 degrees C), oxygen partial pressure pO(2), and humidity pH(2)O. 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 degrees 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 sigma(,)(H+)sigma(-)(o2), sigma(h) in a wide range of temperatures and pO(2) are discussed.

Automated summary

This paper studies the conduction mechanism in perovskite phases with composition La2Me+3ZnO5.5 (Me+3 = Al3+, Sc3+, In3+). The complex oxides exhibit a mixed type of conduction in air, with increasing temperature leading to an increase in electronic contribution. In a wet atmosphere, Sc3+ and In3+ containing samples are capable of incorporating water and forming proton defects, while La2AlZnO5.5 sample shows no significant proton transport.