摘要
BaTib>0.5b>Inb>0.5b>Ob>3鈭?em>未b> was prepared by solid state reaction at 1400聽掳C. Rietveld analysis of high resolution X-ray powder diffraction data indicated phase pure as-prepared material that adopts a cubic perovskite structure with a聽=聽4.1536(1)聽脜. Thermogravimetric analysis revealed the presence of significant levels of protons in the as-prepared material and 57%of the theoretically achievable protonation was attained on exposure to a humid environment at 185聽掳C. After hydration the cell parameter increased to 4.1623(1)聽脜. Electrical conductivity was measured both with fixed and variable frequency ac impedance methods as a function of temperature, oxygen-, water vapour- and heavy water vapour partial pressures. In the temperature range 400-800聽掳C a slight increase in the total conductivity with increasing oxygen partial pressure is encountered, characteristic of a contribution from p-type charge carriers. The effect of the water vapour pressure on conductivity below 600聽掳C is much more prominent indicative of dominant proton conduction. At 300聽掳C the total conductivity in wet Ob>2b> was estimated to be 9.30聽脳聽10鈭?聽S/cm. At T聽>聽800聽掳C the material is a pure oxide ion conductor.