Aging of the linear and nonlinear dielectric susceptibility in a PLZT relaxor system

The aging of the linear and the third order nonlinear complex dielectric susceptibility was investigated in the 9/65/35 PLZT ceramics by monitoring the dielectric response as a function of the waiting time in an experiment using ac and dc measuring electric field. It was found that aging significantly changes low frequency part of the relaxation spectrum of the linear complex dielectric constant. The static value of the dielectric constant follows a power law for long waiting times. Also, it was shown that the third order nonlinear dielectric constant undergoes significant aging for long waiting times, however, it follows slightly different power law than the linear dielectric constant. The possible origin of the aging effects is discussed in terms of the pinning of the polarized nanoclusters.