Phase coexistence in PZT ceramic powders

The paper reports the results of an investigation into the effects of the processing conditions on the observed coexistence of tetragonal and rhombohedral phases in PZT ceramic powders prepared by conventional solid state reaction from the constituent oxides PbO, ZrO2 and TiO2. The processing variables investigated were the composition (the Zr/Ti ratio and the excess lead oxide content) and the calcination temperature. It is shown that these parameters can be related to the degree of chemical homogeneity achieved during processing. For each composition, the degree of tetragonality (for the tetragonal phase) has been determined by high resolution XRD using station 2.3 at the EPSRC Daresbury Laboratory. One observation made in the present work, which has not been discussed previously, is the marked influence of the excess PbO content, combined with calcination temperature, on the homogeneity of the resulting powders. (orig.)