Dielectric relaxation in Cd₂Nb₂O₇ single crystals in temperature range 90-270 K

Abstract

Cd₂Nb₂O₇ single crystals are known to exhibit complex dielectric relaxation behaviour below but in the vicinity of ferroelectric-paraelectrics phase transition. We proceeded to detailed studies of dielectric relaxation in the temperature range 90-270 K and frequencies from 25 Hz to 1 MHz. Two relaxation processes are distinguished and found to overlap when approaching the Curie point from low temperature side. The low frequency relaxation (below 100 kHz), characterized by activation energy of 0.23 eV is ascribed to the relaxation of Cd-0(7) dipoles in “spacious” pyrochlore structure of Cd₂Nb₂O₇, whereas the relaxation characterized by activation energy of 0.70 eV, dominant in the temperature range 160-200 K, is assumed to be domain wall relaxation.