Influence of alkali reagents on phase formation and crystal morphology of hydrothermally derived lead titanate

The influence of three different alkali reagents, i.e. ammonium hydroxide, sodium hydroxide and potassium hydroxide, on phase formation and crystallite morphology of lead titanate prepared under mild hydrothermal conditions was investigated. The formation of three different phases of lead titanate including tetragonal perovskite, tetragonal body-centered and cubic phases, which showed preference to different types of bases, was discussed. The relation between phases and morphology of the hydrothermally derived lead titanate was illustrated. The formation mechanism of lead titanate when various mixtures of ammonium-alkali hydroxide were employed was also discussed. The transmission electron microscopic technique was also employed in the investigation of a typical hydrothermally derived sample revealing the presence of a pyrochlore phase, otherwise undetected by the XRD technique. (c) 2005 Elsevier B.V. All rights reserved.