ELECTRICAL CONDUCTIVITY AND CRYSTAL STRUCTURE OF Ba_2In_2O_5 AT HIGH TEMPERATURES UNDER VARIOUS OXYGEN PARTIAL PRESSURES

摘要

Dependence of the electrical conductivity, σ, of Ba_2In_2O_5 on oxygen partial pressure, Po_2, was examined. Nearly constant log a independent of log Po_2 was observed at 850 ～ 1200°C in a log Po_2 range of -0.7 ～ -3.0. Upward deviation from this constant behavior was detected in brownmillerite phase below 900°C under logPo_2 below -3. This is accompanied with a slight volume expansion. The electrical conductivity under logPo_2 < -3 decreased with decreasing Po_2 in a temperature range of 1000 ～ 1100°C accompanied with the increasing intensity of distorted perovskite phase. At 1200°C,constant log σ was observed in the log Po_2 range of -0.7 ～ -4.0.