Hydrothermal Precipitation of Lead Zirconate Titanate Solid Solutions: Thermodynamic Modeling and Experimental Synthesis

Abstract

A previously developed thermodynamic model of hydro‐thermal synthesis of ceramic powders has been extended to include cases when solid solutions are formed. The model has been applied to the synthesis of a series of lead titanate zirconate solid solutions PbZr x Ti 1– x O 3 (PZT, 0.46 < x ≤ 0.75). It predicts the optimum conditions (i.e., reagent, concentration, pH, and temperature) for the precipitation of phase‐pure homogeneous PZT, provided that the reactants are well mixed. The predictions have been experimentally corroborated using coprecipitated hydrous oxide Zr x Ti 1– x C 2 n H 2 O (0.46 < x ≤ 0.75), as a precursor for Ti and Zr and water‐soluble lead acetate or nitrate salts as a source for Pb. When mixtures of hydrous oxides ZrO 2 · n H 2 O and TiO 2 · n H 2 O were employed as Ti and Zr precursors, independent PbTiO 3 and PbZrO 3 precipitates rather than the PZT solid solutions formed. These results can be rationalized on the basis of reaction kinetics where thermodynamic modeling includes or excludes the possibility of solid‐solution formation.