Stabilisation of polarised clusters in KTaO₃ by Li defects: Formation of a polar glass

Abstract

Dielectric relaxation and electret polarisation effects in KTaO 3:Li have been investigated as a function of Li concentration. The data reveal the presence of polarised clusters which are stabilised by Li impurities and permit a determination to be made of the coherence length for ferroelectric order in KTaO3. Based on the polarisation results, the KTaO3:Li system exhibits characteristics which indicate that it represents an electric dipole analogue of a spin glass and therefore should be termed a 'polar glass'.