Oxide ionic and hole conduction of bismuth titanate polycrystals were investigated by measuring O partial pressure dependence of electrical conductivity. Bismuth titanate exhibited mixed, oxide ion and electron hole, conduction at 600 to 750C. The ionic conductivity was larger than hole conductivity above 600C, and much larger above the Curie temperature (675C). The jump of ionic and hole conductivities was observed around the Curie temperature. Detailed impedance analysis taking inhomogeneity in polycrystalline specimens into account were also performed on the basis of a simple equivalent circuit. Ionic and hole conductivities estimated by impedance calculation showed an excellent agreement with those estimated from O partial pressure dependence of the conductivities.

Estimation of Ionic and Hole Conductivity in Bismuth Titanate Polycrystals at High Temperatures. M.Takahashi, Y.Noguchi, M.Miyayama: Solid State Ionics, 2004, 172[1-4], 325-9