CHARACTERIZATION OF THE FIRING SCHEDULE FOR POSITIVE TEMPERATURE-COEFFICIENT OF RESISTANCE BATIO(3)

The development of positive temperature coefficient of resistance (PTC R) behavior during the firing procedure of semiconducting BaTiO3 was c haracterized. The PTCR properties of BaTiO3 were shown to be sensitive to the material's microstructure, liquid-phase distribution, and exte nt of grain-boundary oxidation, The PTCR behavior first became pronoun ced as the material cooled from the sintering stage at 1350 degrees C to the annealing stage at 1175 degrees C. Within this region, rapid ox idation of the grain boundaries occurred, which resulted in significan t formation of charge carrier traps and a potential barrier, The rapid oxidation of the grain boundaries corresponded with the redistributio n and solidification of the liquid phases, Once the carrier traps were established, the magnitude and slope of the PTCR jump increased durin g the annealing and cool-down stages of the firing procedure because o f further oxidation of the grain boundaries.