Glass transformation, heat capacity and structure of ASxSe1−xglasses studied by modulated temperature differential scanning calorimetry experiments

Abstract

Abstract The recent novel temperature modulated differential scanning calorimetry (MDSCTM TA Instruments Inc. USA) technique has been applied to the measurement of the thermal properties of chalcogenide glasses of the As-Se system in the glass transition region. All samples in this work were given the same thermal history by heating to a temperature above the glass transition, equilibrating and then cooling at a rate of 5°Cmin1 to a temperature of 20°C. The reversing and non-reversing heat flows through the glass transformation region during both heating and cooling schedules were measured and the values of the parameters Tg , ΔH, Cp and ΔCp , which characterize the thermal events in the glass transition region, were determined. The ability to determine the reversible heat flow in MDSC enables an accurate measurement to be made of the true heat capacity (that normally associated with reversible heat flow). This could not be done hitherto in conventional thermal analysis where the detected heat flow is the...