PREPARATION AND AC ELECTRICAL RESPONSE ANALYSIS FOR (BA,PB)TIO3 PTCR CERAMICS

Abstract

For those PTCR materials with higher Pb content, the thermodynamic derivation of increasing values for ''inversion temperature'' and cation vacancy diffusion rate accounts for the increases in the calculated acceptor-state densities N(s) (cm-2). The influence of frequency-dependent properties for the dielectric constant on the calculation of acceptor-state densities is also presented. Applying the concept of suitable value for N(s) to obtain a strong PTC effect, (Ba,Pb)TiO3 PTCR ceramics with Curie point T(c) over 340-degrees-C up to 420-degrees-C have been successfully prepared by adopting higher cooling rates.