Contributions to the Dielectric response from charged domain walls in ferroelectric Pb5Ge3O11

Abstract

In lead geimanate (Pb5Ge3O11) the symmetry is such that only antiparallel domains occur, and the configuration of domains may be evaluated directly in the polarizing microscope through the optical activity associated with spontaneous electric polarization. Dielectric spectra for ε33 in single crystal lead germanate have been measured over the range 10 Hz to 1 MHz, -80°C to +160°C for monodomain and for thermally and electrically depoled samples.Only thermally depoled samples which exhibit charged domain walls show strongly modified dielectric response, with four overlapping but separable contributions to the relaxation spectrum. The mechanisms responsible for enhancing the permittivity and loss in the germanate are discussed.