The Influence of Mechanical Stresses on the Formation of Thin Spherulite PZT Films

Abstract

The influence of mechanical stresses on the growth process of the perovskite–phase in thin ferroelectric films of lead zirconate–titanate on a silicon substrate, manufactured using a two–stage method of high–frequency magnetron deposition, is investigated. Using X–ray diffraction analysis and scanning electron microscopy, the emergence of a spherulitic grain structure with a linear change in the orientation of the growth anisotropy axes along the spherulite radius was established. The results of an analytical and numerical solution of the boundary value problem for determining the stress state during the growth of periodic perovskite cylindrical inclusions in a pyrochlore matrix are presented. It is shown that a monotonic increase in the configuration force at the interphase boundary with distance from the substrate determines a permanent rotation of growth anisotropy during the film formation. Analytical estimates of the stress state of a two–layer plate (film / substrate) under bending caused by transformational strains during the pyrochlore → perovskite phase transition in the film are also presented. A comparison of the calculation results with the measured data of the deviation angle gradient of the growth anisotropy axes demonstrates satisfactory accuracy.