Effect of sintering aids on the electrical properties of positive temperature coefficient of resistivity BaTiO3 ceramics

The effect of sintering aids SiO2, Al2O3, and TiO2 on the microstructure and electrical properties of Sb3+-doped BaTiO3 materials is examined. The SiO2 acts as a liquid-phase former, which not only enhances the atomic diffusion, but also purifies the grain interior and increases the grain conductivity. The room-temperature resistivity of the materials is lowered. An abundance of the liquid phase due to excess TiO2 will, however, result in a clustering of particles and the formation of a nonuniform microstructure. The Al3+ ions inhibit the grain growth and lead to a small and uniform grain size distribution. These ions also act as electron traps which increase the Schottky barrier height and in turn, raise the high-temperature resistivity of the samples.