CRYSTALLIZATION OF NANOMETER-SIZE COPRECIPITATED PBTIO3 POWDERS

Crystallization of coprecipitated PbTiO3 powder was studied by calcining as-precipitated powders at 400-800-degrees-C for up to 262 h. The coprecipitated powders were prepared from a solution containing a 1:1 molar ratio of Pb(NO3)2: TiCl4 and a 1.1:1 molar ratio of H2O2: TiCl4. The solution containing the lead and titanium complexes was slowly added to NH4OH solution under constant pH (10.00 +/- 0.05) conditions that induced precipitation. Transmission electron microscopy and X-ray diffraction indicated that the calcined powders consisted of an intimate mixture of amorphous, cubic (or distorted tetragonal with c(o)/a(o) < 1.01), and tetragonal (c(o)/a(o) = 1.065) PbTiO3 particles between 10 and 400 nm, with both particle size and phase content depending on heat treatment. Powders exhibiting the cubic or distorted tetragonal phase consisted of particles between 20 and 200 nm in diameter. Fully crystalline tetragonal PbTiO3 powders consisting of 100-400 nm particles were prepared.