Temperature and stress dependence of Young’s modulus in semiconducting barium titanate ceramics

In order to study the temperature and stress dependence of Young’s modulus in semiconducting barium titanate ceramics, the longitudinal sound velocity was measured at a frequency of 5 MHz in the temperature range of 20–180 °C. It is striking that at temperatures above the Curie point (Tc=120 °C) the sound velocity reaches values that are 10–20% higher than those at room temperature. Furthermore, a shift of the Curie point of about 2×10−8 K/Pa is observed if uniaxial stress is applied perpendicular to the sound propagation. Both effects can be understood by means of the phenomenological theory of Devonshire.