A MODEL TO SIMULATE COMPLEX DIELECTRIC PERMITTIVITY OF RELAXOR FERROELECTRICS

To model the dielectric behavior of relaxer ferrolectrics, a new distr ibution function and its temperature dependence for the relaxation tim es are introduced. Based on the superparaelectric model, a set of form ula is given to compute the complex dielectric permittivity as a funct ion of both the temperature and frequency. All parameters in the formu la can be experimentally determined. The experimental results of diele ctric behavior for PMN-PT and PZN-PT-BT solid solution ceramics, at fr equencies from 100 Hz to 100 kHz, in the temperature range from -100 d egrees C to 200 degrees C are used to verify the formula. The model sh ows that in the low temperature range epsilon = epsilon(infinity)-B(T) (ln tau(0) + ln omega). Thus, a method to obtain the values of both e psilon(infinity) and tau(0) for the relaxors is described.