Dielectric nonlinearity of relaxor ferroelectric ceramics at low alternating-current-drive amplitudes

The dielectric nonlinear response of (PbMg1/3Nb2/3O3)(0.9) (PbTiO3)(0.1) (0 .9PMN-0.1PT) relaxer ceramics was investigated under different ac-drive vol tages. It was observed that: (i) the dielectric permittivity is independent of the ac-field amplitude at high temperatures; (ii) with increasing ac-dr ive amplitude, the permittivity maximum increases, and the temperature of t he maximum shifts to lower temperature; (iii) the nonlinear effect is weake ned when the measurement frequency increases. The influence of increasing a c-drive amplitude was found to be similar to that of decreasing frequency. It is believed that the dielectric nonlinearities of relaxors at low drive amplitudes can be explained by the phase transition theory of the ergodic s pace undergoing a succession of shrinkages. A Monte Carlo simulation was pe rformed on the hips of micropolarizations at low ac-drive amplitudes to ver ify the theory.