Modelling linear and nonlinear behavior of polycrystalline ferroelectric ceramics

A micro-electromechanical model is presented, which describes the macroscopic behavior of ferroelectric ceramics under weak signal and unipolar large signal loading conditions. The approach is based on a laminar domain structure and a hierarchical homogenization procedure, which considers grains as spherical inclusions within a homogenized effective medium. The model predicts the extrinsic effects of mobile domain walls, hysteresis at large fields, and ferroelectric fatigue by unipolar cycling. Additionally, internal fields can be estimated. As an example, numerical results and available experimental data for barium titanate ceramics are discussed.