Investigation of crystallisation kinetics of Bi0·5Se99·5-xZnx glasses by differential scanning calorimetry

Abstract

The kinetics of crystallisation in Bi_0·5Se_99·5-xZn_x (x=0, 0·1, 0·2, 0·5, 1·0) glasses are studied by non-isothermal method using differential scanning calorimetry. Differential thermal analysis was performed at different heating rates of 5, 10, 15, and 20 K min^-1. The values of glass transition and crystallisation temperatures are found to be composition and heating rate dependent. From the heating rate dependence of the glass transition and crystallisation temperatures, the activation energy of crystallisation ΔE _c, the order parameter n and the enthalpy released ΔH _c are calculated. The thermal stability (T _c–T _g) was found to be maximum for Bi_0·5Se_99·5 glass, which suggest that this glass can be considered as a critical composition at which the system becomes chemically ordered. The crystallisation enthalpy ΔH _c is maximum for Bi_0·5Se₉₉Zn_0·5 glass, hence it is the least stable glass in the present system.