This paper presents a static, temperature dependent constitutive model for polycrystalline relaxor ferroelectrics operating near their diffuse transition temperature. The model assumes that the relaxor material consists of superparaelectric, micro polar regions with a diffuse spectrum of Curie temperatures. A simple Ising model with near neighbor ion interaction represents the thermodynamics of the individual micro polar regions. A random-order dispersion of the B-site ions simulates the distribution of phase transitions. The diffuse micro polar region model predicts two important materials parameters, the saturation polarization and the density of the polar regions, as a function of temperature. A macroscopic model was constructed with these parameters to simulate dielectric and polarization response of the aggregate material. The macroscopic model also accounts for interaction between the micro polar regions. Finally, the predictions made by the model are compared with experimental data obtained by other researchers on lead magnesium niobate (PMN) relaxor ferroelectrics.
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