Pressure and Temperature Dependence of the Dielectric Properties in Barium Titanate

Abstract

Temperature and pressure dependences of the soft-mode frequency (omega) and the dielectric constant (epsilon) are studied for the tetragonal-cubic transition (T-C = 395 K) in BaTiO3. We find that variations of the frequency and the dielectric constant with the temperature (pressure) are related to each other linearly close to the phase transition in this ferroelectric material. Instead of the Curie-Weiss behaviour of the dielectric constant, the critical behaviour of both soft-mode frequency and the dielectric constant is expressed by the power-law formulae, and the critical exponents are determined using the observed data from the literature. Our predicted frequencies of the soft mode at various pressures and temperatures, can be examined by the experimental measurements close to the tetragonal-cubic transition in BaTiO3.