Abstract
Electrical conduction behaviors of bismuth titanate (BiT) and vanadium-doped bismuth titanate (V-BiT) single crystals were investigated by the complex impedance method at high temperatures. Oxygen partial pressure dependence of the electrical conductivity revealed that both BiT and V-BiT showed oxide ionic and p-type mixed conduction properties. In both BiT and V-BiT, ionic conductivity was larger than hole conductivity along the a(b)-axis, while hole conductivity was much larger than ionic conductivity along the c-axis. Vanadium doping largely decreased the ionic and hole conductivities along the a(b)-axis. In contrast, the ionic and hole conductivities of V-BiT along the c-axis were almost the same as those of BiT. It was suggested that bismuth and oxygen vacancies preferentially exist in the pseudo-perovskite blocks in BiT, and vanadium substitution effectively decreases the concentration of oxygen vacancies and holes in the pseudo-perovskite blocks.