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

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