Activation energies during glass transition and fragility of the As30Te64Ga6 chalcogenide glass

Glass transition features of chalcogenides are important for the broad and increasing industrial applications of these glassy semiconductors. Hence, differential scanning calorimetry was applied at different scanning rates on As30Te64Ga6 prepared by conventional melt quenching technique in order to study their glass transition and fragility. The Kauzmann temperature was estimated to about 136 K while its glass transition is about 397 K at 10 K min(-1). Different experimental evaluation methods gave the same fragility index m = 25 or D = 71 which is typical of a strong liquid corresponding to the prepared glass. Four iso-conversional methods were then applied to monitor the change in the activation energy for the temperature range corresponding to the transition from glass to liquid. All methods give a small monotonic decrease of the activation energy during transition from 108 to 99 kJ mol(-1) confirming the strong character.