INFLUENCE OF SINTERING PROFILE ON THE RESISTIVITY OF LOW-CURIE-POINT PTCR CERAMICS

Abstract

The influence of sintering profile, with emphasis on the effect of soaking treatment and cooling rate, on the resistivity of low-Curie-point positive temperature coefficient of resistivity (PTCR) ceramics has been investigated. Soaking treatment at 1200-degrees-C or slower cooling rate were found to result in an increase in the room-temperature and maximum values of resistivity in the resistivity-temperature characteristics. The surface acceptor density (N(s)), whose value was extracted from the capacitance-voltage measurement, was found to increase with soaking treatment at 1200-degrees-C or slower cooling rate. From derivations based on the Heywang-Jonker model, higher room-temperature and maximum resistivities are expected to occur as a result of increasing N(s), as confirmed by the experimental data.