Synthesis by the citrate route and characterisation of BaZrO3, a high tech ceramic oxide:: preliminary results

In this work a route for BaZrO3 synthesis that assures homogeneity and stoichiometry of the final powder is proposed. The route consists in the complexation of the metallic ions by citric acid and ammonia in an aqueous solution. After an accurate drying of the initial solution, the crystalline phase of barium zirconate is obtained at relatively low temperature (about 700 degrees C) and in relative short times utilising cheap starting reagents. A detailed description of the different steps of a preparation of 300 g of final product and a comparison with BaZrO3 powders produced by a typical solid state reaction are reported. The powders are characterised during the various steps by thermal analysis (DTA-TGA) and by structural and morphological techniques (XRD, FTIR and granulometric measurements). A preliminary investigation of the sintering process is reported: SEM imaging and dilatometric measurements were performed to evaluate different sintering behaviours of the powders prepared by wet and solid state methods. (C) 1999 Elsevier Science Ltd. All rights reserved.