Crystallization behaviour and phase coexistence at morphotrophic phase boundaries in PZT thin films prepared by sol-gel processing

Pb(Zr_0.53Ti_0.47)O₃ (PZT) thin films, prepared by sol-gel techniques and deposited on to Si/SiO₂/Ti/Pt substrates, have been subjected to thermal annealing in a range of temperatures from 550–800 °C. The crystallization behaviour and phase coexistence (tetragonal and rhombohedral) were studied by X-ray diffraction. According to the values of the {110} peak intensity and {110} peak values, the crystallization full-width at half-maximum was more complete at higher temperatures (750, 800 °C). At a fixed Zr/Ti ratio close to the morphotropic phase boundary, the lattice parameters of the two phases changed with the annealing temperature. However, 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 {0 1 1} titanium rich layer at Pt-PZT interface will supply a titanium excess for the nucleation and growth of textured PZT grains.