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

In this work a route for BaZrO3 synthesis that assures homogeneity and stoi chiometry of the final powder is proposed. The route consists in the comple xation of the metallic ions by citric acid and ammonia in an aqueous soluti on. After an accurate drying of the initial solution, the crystalline phase of barium zirconate is obtained at relatively low temperature (about 700 d egrees C) and in relative short times utilising cheap starting reagents. A detailed description of the different steps of a preparation of 300 g of fi nal product and a comparison with BaZrO3 powders produced by a typical soli d state reaction are reported. The powders are characterised during the var ious steps by thermal analysis (DTA-TGA) and by structural and morphologica l techniques (XRD, FTIR and granulometric measurements). A preliminary inve stigation of the sintering process is reported: SEM imaging and dilatometri c measurements were performed to evaluate different sintering behaviours of the powders prepared by wet and solid state methods. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.