欠陥ペロブスカイトLaTa₃O₉の交流電気伝導と輸率測定

抄録

A. C. electrical properties of defect-perovskite LaTa₃O₉ were measured in the temperature range between 423 and 1073 K under oxygen partial pressures (P_o2) from 10Pa to 0.1 MPa. Complex impedance spectra showed three dispersions associated with bulk, surface layer and a diffusion (Warburg) process. The conductivity of bulk was independent of P_o2 and its activation energy. was 0.40 to 0.48 eV. The capacitance of bulk was 5 to 8 pF and independent of temperature. The conductivity of surface layer (σ₂) increased with increasing P_o2, as expressed by σ₂∝P_o2ⁿ (n=0.14 to 0.18). The capacitance of surface layer increased from 3 to 20 nF and increased with increasing temperature. The ionic transport number measured with an oxygen concentration cell was nearly 1 at 750 K, and decreased with increasing temperature.