CRYSTALLISATION BEHAVIOUR AND PHASE COEXISTENCE AT MORPHOTROPIC PHASE BOUNDARIES IN PZT THIN FILMS PREPARED BY SOL-GEL PROCESSING

Pb(Zr0.53Ti0.47)O3 (PZT) thin films, prepared by sol-gel techniques and deposited on to Si/SiO2/Ti/Pt substrates, were subjected to thermal annealing in the temperature range 550-800 C. The crystallisation behaviour and phase coexistence (tetragonal and rhombohedral) were studied by XRD. According to the values of the 110 peak intensity and 110 peak values, the crystallisation full-width at half-maximum was more complete at higher temperatures (750, 800 C). At a fixed Zr/Ti ratio close to the morphotrophic phase boundary, the lattice parameters of the two phases changed with the annealing temperature. The tetragonality degree had relatively low values and the angular rhombohedral distortion was associated with a narrow angular range. The phase coexistence and the variation of the lattice parameters could be explained by the titanium diffusion through the platinum layer. Thus the formation of a 011 titanium rich layer at Pt-PZT interface will supply a titanium excess for the nucleation and growth of textured PZT grains. 12 refs.