EFFECTS OF MICROSTRUCTURE ON THE DIELECTRIC BREAKDOWN OF POLYCRYSTALLINE BaTiO//3.

Abstract

Dielectric and mechanical strengths in polycrystalline BaTiO//3 were measured as a function of grain size at 140 degree C and 25 degree C, where grain size was controlled by sintering time at 1335 degree C. Both the dielectric and the mechanical strengths decreased with grain size. The mechanical strength was higher at 140 degree C than at 25 degree C. Though some analogy between the dielectric and the mechanical strengths has been proposed, the mechanism of dielectric breakdown in barium titanate ceramics seems to be different from that of mechanical fracture.