Non-isothermal crystallization kinetic study on Ga 15Se 85− xAg x chalcogenide glasses by using differential scanning calorimetry

Abstract

At different heating rates, the glass transition temperature ( T g ) and the crystallization temperature ( T c ) are obtained from the non-isothermal differential scanning calorimetry (DSC) measurements of bulk Ga 15Se 85− x Ag x ( x = 0, 2, 4, 6 and 8) chalcogenide glasses prepared by melt quenching technique. Their amorphous state was verified by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was observed that the glass transition temperature and crystallization temperatures both increase with increasing heating rates and also by increasing Ag concentration in Ga–Se system. The activation energy of crystallization ( E c ), activation energy of glass transition ( E g ), crystallization enthalpy (Δ H c ) and the Avrami exponent ( n) have been determined from the dependence of T g and T c on the heating rate ( β). The obtained value of the n indicates that the volume nucleation with two dimensional growth is responsible for amorphous-crystallization phase transformation. On the basis of the obtained experimental data, the temperature difference ( T g − T c ) and the enthalpy released (Δ H c ) are found to be maximum and minimum, respectively, for Ga 15Se 77Ag 8 glass, which indicate that this glass is thermally most stable in the composition range under investigation. The crystallization kinetic study of Ga 15Se 85− x Ag x glass was studied by using the modified Kissinger and Ozawa equations.