MODELING ON THE RESISTIVITY-TEMPERATURE PROPERTIES OF (PB0.6SR0.4)TIO3 MATERIALS PREPARED BY THE RAPID THERMAL SINTERING PROCESS

A core-shell microstructure is adopted to account for the unique resis tivity-temperature (rho-T) behavior of (Pb0.6Sr0.4)TiO3 materials prep ared by the rapid thermal sintering (RTS) process. instead of a V-shap ed temperature coefficient of resistivity (VTCR) with critical tempera ture (T-c1') at around 200 degrees C, commonly observed for the materi als prepared by conventional sintering process, a rho-T curve with sin gle high T-c2 congruent to 440 degrees C is obtained. Moreover, the co oling rate after the RTS process markedly influences the rho-T behavio r. The apparent resistivity and the negative temperature coefficient o f resistivity (NTCR) decrease as the cooling rate increases. The criti cal temperature (T-c2) for abrupt resistivity jump is insignificantly varied. These phenomena are ascribed to the modification of the thickn ess of the shell region due to the interdiffusion between the core and shell materials during the cooling stage. A simplified microstructura l model is used to simulate the temperature dependence of resistivity and clearly explains the electrical behavior of these RTS samples.