The aging behaviour of the complex material parameters ε, d and s in ferroelectric PZT ceramics

The complex dielectric constant ε as well as the complex piezoelectric constant d and the complex elastic constant s of iron doped PZT ceramics were measured after poling as a function of time. It was found that the aging behaviour of the material parameters is similar. The time dependence of the losses shows that aging effects due to 180°-domain wall processes are, if present, small. Aging is caused by 90°-domain walls, either by a reduction of the domain wall area or by a reduction of their mobility. A procedure for the separation of the volume and domain wall contribution to the real parts is presented.