Bc. Lacourse et Vrw. Amarakoon, CHARACTERIZATION OF THE FIRING SCHEDULE FOR POSITIVE TEMPERATURE-COEFFICIENT OF RESISTANCE BATIO(3), Journal of the American Ceramic Society, 78(12), 1995, pp. 3352-3356
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.