The structure of As xS 100− x glasses studied by temperature-modulated differential scanning calorimetry and Raman spectroscopy

Abstract

A novel temperature modulated differential scanning calorimetry (MDSC) technique has been applied to the measurement of the thermal properties of As x S 100− x chalcogenide glasses in the glass transition region. All samples in this work have the same thermal history. The parameters glass transition temperature ( T g), relaxation enthalpy (Δ H), heat capacity ( C p) and change of heat capacity (Δ C p), which describe the thermal events in the glass transition region, were measured. The structurally determined parameters T g, Δ H, C p and Δ C p have extrema when the composition of As x S 100− x glasses is As 28.5S 71.5 and As 40S 60. We show that As x S 100− x glasses where x<25 at.% As are formed from two glass phases. From MDSC measurements, it was possible to establish the probable composition of the high temperature glass phase and, further, by using Raman spectroscopy, it was possible to correlate the MDSC results with the structure of the As–S glasses.