Effect of Lead Zirconate on Positive‐Temperature‐Coefficient Materials

The addition of small amounts of PbZrO 3 to (Pb,Ba) TiO 3 suitably doped to give positive‐temperature‐coefficient behavior resulted in a aramatic change in the resistivity‐temperature properties of the material. The results are explained on the basis of a synergy between Zr content and Pb volatilization in titanate‐based perovskites which favors partial compensation of the Pb vacancies with holes. A secondary result explains the pronounced grain growth which occurs at doping levels where semiconduction begins as being due to a minimum in the vacancy content which results in secondary recrystallization.