Mechanism of PZT crystallisation under hydrothermal conditions - Development of a new synthesis route

On the basis of a 1-stage hydrothermal process, we first investigated the r eaction mechanism responsible for the PZT precipitation. In a first sequenc e, lead diffuses into the amorphous coprecipitate. By increasing the reacti on temperature, these particles dissolve, leading to nucleation and growth of PZT well faceted particles. In a second step, we demonstrated that start ing from very fine oxide precursors, a homogeneous PZT solid solution could be formed. Under the same conditions but without any lead precursor, a mix ture of KTO (a potassium titanium oxide phase) and tetragonal zirconia is f ormed. A 2-stage process was developed on these assumptions. The first stag e consists in producing the KTO-ZrO2(T) mixture. In the second stage, this mixture is hydrothermally treated in presence of lead precursor. Pure and h omogeneous PZT and PLZT powders were obtained throughout this new synthesis route. (C) 2000 Elsevier Science Ltd. All rights reserved.