Abstract
The resistivity-temperature (ρ{variant}-T) characteristics of the (Sr 0.4 Pb 0.6 )TiO 3 materials prepared by the microwave sintering process were examined. The resistivities varied insignificantly with sintering temperature (1000-1100 °C) and soaking time (10-30 min), but increased markedly as the cooling rate reduced or as the heat-treatment temperature increased. The Curie temperature was not altered by the cooling rate control process but was shifted from T c = 302 to 210 °C when the as-sintered samples were post-heat-treated at 1100 °C for 1 h. The high Curie temperature of the as-sintered samples was proposed to result from the core-shell structure of the grains. The 'shell', which contained Pb-rich perovskite of composition (Sr 0.29 Pb 0.71 )TiO 3 , was homogenized with the 'core' during heat treatment such that the Curie temperature approached T c = 210 °C, as the composition of the 'shell' reduced to the designed value, (Sr 0.4 Pb 0.6 )TiO 3 . © 1995.