EFFECTS OF PH AND H2O2 UPON COPRECIPITATED PBTIO3 POWDERS .2. PROPERTIES OF CALCINED POWDERS

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 = 1.1:1.1, and pH = 9.65 to 9.75.