Metastability in the commensurate phase of

Department of Physics and Research Center for Dielectric and Advanced Matter Physics Pusan National University - Pusan, 609-735, Korea

Received: 8 February 2000
Accepted: 23 February 2001

Abstract

A new dielectric anomaly is found at the temperature (260-290 K) in the commensurate (C) phase of , which separates the commensurate phase into two states. The C phase above is a metastable state, in which the relaxation of the polarization is expressed by the stretched exponential form, and the C phase below is a stable state in which the dielectric constant and polarization are independent of time. It is speculated that the dielectric anomaly found at the temperature is a stabilization process of discommensurations. This anomaly could be observed only in a measurement performed using a liquid-nitrogen cooler (LNC) without mechanical vibration of the measurement system.