Fabrication and Characterization of Semiconductive Ceramics using BaTiO3-(Bi1/2K1/2)TiO3 System

As a candidate of a lead-free positive temperature coefficient of resistivitiy (PTC) themistor material, barium titanate (BaTiO₃) -based solid-solution ceramics, BaTiO₃-(Bi_1/2K_1/2)TiO₃ (BBKT100x), have been synthesized by the conventional ceramic fabrication technique. The maximum temperature of the dielectric constant (T_m) of the BBKTIOOx ceramics monotonously increased with the increasing amount of x. The Tm values of the BBKTIOOx ceramics with x>0.0 were higher than that of BaTiO₃ (=130degC). The peak temperature (T_p) of the pyroelectric coefficient showed that the ferroelectricity of the BBKT100x ceramics disappeared at Tm. The reduced BBKT5 ceramics show PTC characteristics as well as a semiconductivity.