Intrinsic nonstoichiometry in the lead zirconate-lead titanate system determined by Knudsen effusion

Abstract

The range of the intrinsic nonstoichiometry in lead zirconate-titanate at 1100 °C has been established independently by two gravimetric techniques. A modified Knudsen effusion experiment allowed for an extended interpretation of the vapor pressure data. A single experiment was used to determine the width of any Pb1−x □x (TiyZr1−y)O3−xφx single-phase region, the equilibrium PbO vapor pressure, activity data as a function of both temperature and composition, and the exact location of the stoichiometric composition within the single-phase region. The ``vapor phase equilibration'' (VPE) method was used as a supplemental measurement of the width of most PZT single-phase regions. Results obtained by the two methods for the extent of nonstoichiometry were in close agreement (xmax = 0.10 at y = 1.0; xmin = 0.016 at y = 0.40; T = 1100°C). The Knudsen effusion experiment established that for all the compositions studied, the stoichiometric composition, Pb(TiyZr1−y)O3, was coincident with the (liquid + PZT) phase boundary.