Evolution of Microstructure and V‐Shaped Positive Temperature Coefficient of Resistivity of (Pb _0.6 Sr _0.4 )TiO ₃ Materials

Abstract

The effects of various liquid‐phase sintering aids on (Pb 0.6 SrO 0.4 )TiO 3 ceramics have been investigated. The relationships between electrical properties and microstructures have been scrutinized. It has been found that, among the sintering aids studied, only SiO 2 exhibits a significant effect on the grain growth of (Pb 0.6 SrO 4 )TiO 3 . The optimum firing profiles for sound microstructure and good electrical properties of (Pb 0.6 SrO 0.4 )TiO 3 + 5.0 mol% SiO 2 have been established. The V‐shaped electrical behavior is prominent, and a PTCR jump of about 10 2.9 is observed. The formation of cation vacancies may increase the resistivity of the over‐fired specimens. Various milling methods to pulverize the calcined powder and the optimum amount of packing protection powder during sintering are also discussed.