COMPOSITIONAL CHANGE AND COMPOSITIONAL FLUCTUATION IN PB(ZR, TI)O-3 CONTAINING EXCESS PBO

Compositional changes which take place during sintering of Pb(Zr,Ti)O-3 (PZT) containing excess PbO were studied. The excess PbO forms a liquid phase during the sintering process, The solubility of the TiO2 component of PZT in liquid PbO is higher than that of ZrO2 component. Thus, if an excess PbO exists, the composition of PZT phase shifts towards the Ti-lean side. A change in the lattice constants due to this compositional change was actually observed. Coexistence of tetragonal and rhombohedral phases, due to a compositional fluctuation caused by excess PbO, was observed near the morphotropic phase boundary, When PZT containing excess PbO was sintered at 1100 degrees C, a compositional fluctuation occurred early in the process and then decreased with sintering time. These phenomena have agreed with a result of computer simulation of dissolution of TiO2 component in PZT phase into liquid PbO phase.