Numerical Simulation On The Behavior Of Ferroelectrics Thin Film

The ferroelectrics polycrystal consists of a set of bonded crystal and each crystal comprises a set of distinct domain under mesoscale. With each domain being Looked as distinct material phases and ferroelectrics polycrystal as multiphase material, the coupled macroscopic thermo-electric-mechanical behavior of polycrystalline ferroelectrics can be induced by multi-scale analyze .In response to the applied stimuli, domain can switch and domain switching coverts one variant into another. The rate of domain switching plays an important role in the nonlinear behavior and properties that are frequency dependent .It is necessary to incorporate the rate of domain switching when multi-scale analysis of the coupled macroscopic thermo-electric-mechanical behavior of ferroelectrics is carried out. Homogenization techniques in multi-scale analysis, the description of domain switching and the effect that the rate of domain switching has on the macroscopic behavior of ferroelectrics are the main subjects discussed in this paper.In chapter one, we briefly recount some properties of ferroelectrics and review the research history, approaches and actuality in domestic and overseas.In chapter two, the theory of thermodynamics is narrated.In chapter three, homogenization technique of multiphase is discussed. A new way of defining the effective physical quantities by other apparent physical quantities is proposed. Accordingly, a new framework, which provides a common scheme for the numerical simulation on the macroscopic behavior of ferroelectrics though multi-scale analysis on the coupled thermo-electrics-mechanical behavior of multiphase in heterogeneous material, is induced to construct the effective constitutive equation of multiphase.In chapter four, based on the law of domain nucleation and domain wall motion of 1800 domain switching, a new scheme of domain switching and numerical simulation approach is put forward on the foundation of thermodynamics. Driving traction, nucleation criterion, velocity of domain wall motion, kinetic relation and rate of domain switching in a single grain are given. According to mesomechanics model, multi-scale analysis, which includes the rate of domain switching, on the coupledthermo-electric-mechanical behavior of polycrystalline ferroelectrics is brought forward.In chapter five, neglecting the cross-coupling between mechanical and electrical fields, we establish a one-dimension model of ferroelectrics thin film under the electric field which parallel to direction along the thickness of the film. The numerical simulation of D-E hysteresis loop, the frequency dependency of dielectric constant, frequency dependency of loss tangent and evolution of initial D-E hysteresis loop are carried out. In chapter six, taking account of the cross-coupling between mechanical and electrical fields, we construct a one-dimension model of ferroelectrics thin film under the electric field and normal restrict , which parallel to direction along the thickness of the film. The numerical Simulation of D-E hysteresis loop and butterfly hysteresis loop of ferroelectrics thin film is given. The effect of normal stress on the D-E hysteresis loop and the butterfly hysteresis loop are predicted.