Evaluation of Piezoelectric and Dielectric Properties of Unpoled and Poled Barium Titanate Polycrystals with Oxegen Vacancies using Phase Field Method

Abstract

This paper studies the dielectric and piezoelectric behavior of unpoled and poled barium titanate (BaTiO₃) polycrystals with oxygen vacancies. A phase field model is employed for BaTiO₃ polycrystals, coupled with the time-dependent Ginzburg-Landau theory and the oxygen vacancies diffusion, to demonstrate the interaction between oxygen vacancies and domain evolutions. To generate grain structures, the phase field model for grain growth is also used. The hysteresis loop and butterfly curve are predicted at room and high temperatures. The permittivity, and longitudinal and transverse piezoelectric constants of the BaTiO₃ polycrystals are then examined for various grain sizes and oxygen vacancy densities.