Solubility Limit of La in the Lead Zirconate‐Titanate System

The disappearing‐phase method was used to determine the extent of the solid‐solution region of the PLZT system for conventionally sintered ceramics prepared at 1100° and 1300°C in a PbO atmosphere provided by pbZrO 3 . A decrease in the firing temperature from 1300° to 1100°C lowers the solubility limit by 5 to 8 at.% La. Beyond the limits of solubility, additional La forms La 2 Zr 2 O 7 and/or La 2 Ti 2 O 7 . The limit determined by the disappearing‐phase method (1300°C firing) is compared to values determined by the parametric method. The Curie temperature is stabilized at 5 at.% La for modified PbZrO 3 (1300°C firing).