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 an d rhombohedral phases in PZT ceramic powders prepared by conventional solid state reaction from the constituent oxides PbO, ZrO2 and TiO2. T he processing variables investigated were the composition (the Zr/Ti r atio and the excess lead oxide content) and the calcination temperatur e. It is shown that these parameters can be related to the degree of c hemical homogeneity achieved during processing. For each composition, the degree of tetragonality (for the tetragonal phase) has been determ ined by high resolution XRD using station 2.3 at the EPSRC Daresbury L aboratory. One observation made in the present work, which has not bee n discussed previously, is the marked influence of the excess PbO cont ent, combined with calcination temperature, on the homogeneity of the resulting powders.