Electric properties of oxyfluorides Ba2In2O5-0.5xF x with brownmillerite structure

Synthesis of fluoro-substituted substances based on brownmillerite Ba2In2O5 is carried out. The width of the homogeneity region of the Ba2In2O5-0.5x F (x) (0 < x a parts per thousand currency sign 0.25) solid solution was established using X-ray analysis. Measurement of temperature dependences of conductivity in atmospheres with different partial pressure of water vapor (pH(2)O = 3.3 and 2 x 10(3) Pa) showed an increase in conductivity at T a parts per thousand currency sign 550A degrees C in a humid atmosphere, which is due to appearance of proton transport. The dependence of conductivity on partial oxygen pressure (pO(2) = 0.21 x 10(5) to 10(-15) Pa) is studied in the temperature range of 500-1000A degrees C; ion transport numbers are calculated. The method of polarization measurements was used to determine transport numbers of fluoride. Total conductivity is divided into ion (proton, oxygen, and fluoride ion) and electron components. Analysis of concentration dependences of conductivities showed that low concentrations of fluoride allow increasing both the total and partial conductivities (oxygen-ion and proton) and, besides, allow shifting the order-disorder phase transition by 100A degrees C to the low temperature range.