Damping constant, dielectric susceptibility, inverse relaxation time and the activation energy calculated as a function of temperature from the Raman frequency for the rhombohedral-tetragonal phase transition in BaCeO3

Abstract

Temperature dependences of the damping constant (half width at half maximum), dielectric susceptibility, inverse relaxation time and the activation energy of the 110 cm -1 and 125 cm -1 Raman modes are calculated in the ferroelectric phase (T<T C ) of BaCeO 3 . Observed frequencies of the Raman modes studied are related with the order parameter (spontaneous polarization) to calculate the damping constant from the pseudospin-phonon coupled (PS) model and the energy fluctuation (EF) model for the orthorhombic-tetragonal transition in BaCeO 3 (T C = 427 K). Our calculated values for the damping constant from both models are in good agreement with the observed data. The inverse relaxation time of those Raman modes are predicted using the calculated values of the damping constant from both models (PS and EF) and the values of the order parameter (squared). Dielectric susceptibility is also predicted through the observed Raman frequencies of the modes studied by using the Landau phenomenological theory. Our calculated values of the inverse relaxation time and the dielectric susceptibility of the 110 cm -1 and 125 cm -1 Raman modes of BaCeO 3 can be compared with the experimental data when they are available in the literature. Finally, we extract the values of the activation energy from the damping constant calculated from both models for the Raman modes studied in the ferroelectric phase of BaCeO 3 .