Phase transitional studies of polycrystalline Pb0.4Sr0.6TiO3 films using Raman scattering

Abstract

Pb 0.4 Sr 0.6 TiO 3 films with submicron size grains have been prepared on Pt substrates by the metalorganic decomposition method. X-ray diffraction analysis reveals that the films are polycrystalline with a perovskite crystal structure and negligible tetragonal splitting at room temperature. The room temperature Raman spectrum, however, shows all the characteristic phonon modes of a tetragonal ferroelectric phase. These modes lose their intensity with an increase in temperature but persist even up to 150 °C. This is in agreement with the dielectric permittivity versus temperature data which show a broad peak–room temperature, and ferroelectric hysteresis persisting up to ∼140 °C. Both Raman and dielectric data are interpreted as due to the presence of a distribution of phases in the film perhaps caused by a variation in Pb content along the film thickness and/or near grain boundary regions.