Effect of three-stage isothermal annealing on the nucleation process in GeSe2 glasses

Abstract

We studied the mechanism of crystallization of GeSe2 bulk glass into the so-called low-temperature GeSe2 crystalline phase. Initial isothermal annealing at a temperature T1 below 400 °C and subsequent isothermal crystallization at 440 °C were carried out in a differential scanning calorimeter (DSC). The crystallization time (tc), defined by the interval from the onset of annealing at 440 °C to the observation of a DSC peak, became shorter with increasing T1. Nucleation occurs during this initial annealing. Next, T1 was fixed at 330 °C and specimens were subsequently annealed at T2<T1. It was found that tc increased as T2 decreased from 330 °C. The nuclei generated at T1 were reconverted to the glassy state.