Pyrochlore-to-perovskite transformation in solution-derived lead zirconate titanate thin films

摘要

The authors have characterized the pyrochlore-to-perovskite crystallization process in solution-derived Pb(Zr(sub 0.20)Ti(sub 0.80))O(sub 3) thin films on (100) MgO single crystal substrates. It has been determined that the perovskite phase nucleated preferentially at the film/MgO interface out of a nanocrystalline ((approx)100(angstrom) grains) pyrochlore matrix. During the early stages of the pyrochlore-to-perovskite conversion process, perovskite growth proceeded nearly isotropically from the substrate to form hemispherically shaped grains. Deviations from isotropic growth were shown to result from a growth dependence based on the crystallographic orientation of a growing perovskite grain relative to the orientations of pyrochlore grains being transformed. The volume change that occurs during the pyrochlore-to-perovskite transformation along with two-dimensional grain growth has been used to develop a mechanism for formation of porosity that commonly is concentrated in grain boundary regions.