SEMICONDUCTING BARIUM-TITANATE CERAMICS PREPARED BY BORON-CONTAINING LIQUID-PHASE SINTERING

Semiconducting BaTiO3 ceramics have been prepared by adding BN as a sintering aid. Density as high as 93% of theoretical and grain size as large as 16 mum are obtained after sintering at 1160-degrees-C. Most significant is that the semiconducting BaTiO3 is obtained at sintering temperatures as low as 1100-degrees-C. The low-temperature-sintered BaTiO3 exhibits a positive temperature coefficient (PTC) anomaly above 120-degrees-C with a resistivity maximum at a temperature as high as 400-degrees-C, which is much higher than that of the conventional BaTiO3. The incorporation of B into the perovskite structure is negligible. Also, the presence of B at a grain boundary after sintering is believed to enhance the PTC effect.