Dielectric relaxation and charged domain walls in (K,Na)NbO_3-based ferroelectric ceramics

摘要

The influence of domain walls on the macroscopic properties of ferroelectric materials is a well known phenomenon. Commonly, such "extrinsic" contributions to dielectric permittivity are discussed in terms of domain wall displacements under external electric field. In this work, we report on a possible contribution of charged domain walls to low frequency (10-10~6Hz) dielectric permittivity in K_(1-x)Na_xNbO_3 ferroelectric ceramics. It is shown that the effective dielectric response increases with increasing domain wall density. The effect has been attributed to the Max well-Wagner-Sillars relaxation. The obtained results may open up possibilities for domain wall engineering in various ferroelectric materials.