Dielectric Relaxation Studies in OBT al Low Temperatures

Abstract

Dielectric measurements have been made in the stable and metastable solid modifications of n(p-octyloxybenzylidence)-p-toluidine (OBT) in the frequency range 0.5 to 100 KHz and in the temperature range – 180 to +40[ddot] C. While cooling rapidly for metastable modification, the OBT first attained glassy phase I and thereafter changed to glassy phase II at a temperature of about -45[ddot] C. On heating, the metastable phase converts to stable crystalline phase at a characteristic temperature of about +23[ddot] C. The dielectric dispersion was absent in the stable phase while in the metastable modification an asymmetrical distribution of relaxation times was seen. The dispersion mechanism for glassy phase II and I identified as β and x relaxation processes have been attributed due to the group orientation and free orientation of the molecules about their long axes respectively.