Effects of pH and H₂O₂ upon coprecipitated PbTiO₃ powders

Abstract

PbTiO₃ was prepared by coprecipitation and calcination from mixed solutions of TiCl₄ and Pb(NO₃)₂. The effect of pH in the precipitation solution on the properties of calcined powders was studied by calcining coprecipitated precursor powders prepared at pH values between 8.00 and 10.50. The effects of H₂O₂ were studied by preparing PbTiO₃ powders from mixed solutions containing H₂O₂∶PbTiO₃ ratios between 0∶1 and 6∶1. Synthesis of phase pure PbTiO₃ by coprecipitation and calcination is highly dependent upon the complex ionic equilibria dictated by the pH. The pH used for precipitation determines the types of crystalline phases formed from coprecipitated precursor powders. The rate at which amorphous precipitates transform to crystalline PbTiO₃ during calcination is also affected by both the pH and H₂O₂ additions. High purity (greater than 98%) PbTiO₃ with a rapid amorphous-to-crystalline transformation rate was obtained for H₂O₂∶PbTiO₃=1.1∶1, and pH=9.65 to 9.75.