Morphotropic phase transition studies in by far-infrared reflectance spectroscopy

The morphotropic phase transition in the system has been studied by far-infrared reflectance spectroscopy. The reflectance measurements are performed on compositions with x = 0.0, 0.10, 0.20, 0.30, 0.35, 0.40 and 0.525 at room temperature in the frequency range . The spectrum is fitted with a model based on the factorized form of the dielectric function. The dependences of the mode frequencies, damping and oscillator strength on x are reported. The static dielectric constant is calculated from the frequencies obtained from the fitting. The observed experimental data show incomplete softening of the lowest E(1TO) mode towards the morphotropic phase boundary. The oscillator strength of the lowest mode carries nearly all the contribution to the lattice part of the dielectric constant.