Kinematical studies of glass transition in Se100-xTexby DSC technique

Abstract

ABSTRACT The present paper reports the kinematical studies of glasstransition in Se100Te glassy alloys using Differential ScanningCalorimetry technique. From the heating rate dependence of glasstransition temperature, the activation energy (AEt) for the relaxa—1tion time controlling the structural enthalpy, is calculated and itscomposition dependence is discussed in terms of the structure ofSe-Te glassy system.1. 1NTRODUCTIOIt is well known [1-4] that thermal relaxation occursinchalcogertide glasses when a glassy substance, following an instan-taneous change in temperature (during quenching process), relaxesfrom a state of higher enthalpy towards aequilibrium state of lowerenthalpy. This type of thermal relaxation depends upon the tempera-ture of anneal and may be quite fast near glass transition tempera— ture. Normally, a shift in the .base line or an end othermic peak is observed in Differential Thermal Analysis (DTA) or DifferentialScanning Calorimetry (DSC) due to a change in specific heat. However,in chalcogenide glasses, such an endothermic peak can also be obser—ved due to fast increase in the enthalpy when the glassy systemrelaxes quickly due to a decrease in viscosity at glass transitiontemperature. DTA or DSC technique can, therefore, be quite usefulin the study of thermal relaxation in these glasses. Some suchattempts have already been made in Se based chalcogenide glasses