Impedance spectroscopy studies of 0.7Bi(Fe1−xGax)O3-0.3PbTiO3 high temperature piezoelectric ceramics

Crystalline solutions of 0.7Bi(Fe1−xGax)O3-0.3PbTiO3 (BGF-PT) of x = 0, 0.05 and 0.1 were fabricated by solid-state reaction method. X-ray diffraction results indicated that BGF-PT ceramics showed single perovskite structure, and Ga was incorporated into the BGF-PT system. Impedance spectroscopy studies revealed that there were two types of relaxation processes indicating two electro active regions (grain and grain boundary) in BGF-PT of x = 0 over the frequency and temperature range studied, whereas there was only one (grain) for BGF-PT of x = 0.05 and 0.1. Further investigation reflected that the high temperature resistivity of BGF-PT had been improved significantly by Ga modification, which was probably owing to enhanced grain resistivity by reduced defect concentration in the solid solutions.