Calorimetric and Optical Study of Amorphous Se85 − xTe15Bix Glassy Alloy

Abstract

Bulk samples of Se85 − xTe15Bix (where x=0, 1, 2, 3, 4, 5) glassy alloys are obtained by melt quenching technique. Differential scanning calorimetric (DSC) technique has been applied to determine the thermal properties of Se-rich Se85 − xTe15Bix glassy alloys in the glass transition and crystallization regions at four heating rates (5, 10, 15, 20 K min−1). The glass transition temperature (Tg) and peak crystallization temperature(Tp) are found to shift to a higher temperature with increasing heating rate. With Bi addition, the value of (Tg)increases. (Tp) is found to increase as Bi is introduced to the Se–Te host, however further increase in Bi concentration is responsible for the reduction of. Thin film of bulk samples are deposited on glass substrate using thermal evaporation technique under vacuum for optical characterization. Optical band gap is estimated using Tauc's extrapolation and is found to decrease from 1.46 to 1.24 eV with the Bi addition.