Dynamics of domain wall motion and domain pattern coarsening in ferroelectric sodium nitrite

Abstract

The temperature dependence of the low frequency dielectric dispersion caused by domain wall motion has been studied. The dispersion strength increases monotonically from room temperature toward T_c, while the relaxation frequency increases first, reaches a maximum around 130°C and then drops rapidly toward T_c. The observed slowing down of domain wall motion is explained as a result of weakening of impurity pinning toward T_c. The process of domain pattern coarsening has been studied by observing the time evolution of the dielectric dispersion. The average domain width increasa as t in the late stage of the coarsening process in agreement with the result of kink dynamics developed by Kawasaki, Ohta and Nagai.