Temperature-Modulated Differential Scanning Calorimetry Analysis of High-Temperature Silicate Glasses

Differential scanning calorimetry (DSC) is one of the most versatile probes for silicate glasses, allowing determination of, e.g., transition temperatures (glass, crystallization, melting) and the temperature dependence of heat capacity. However, complications arise for glasses featuring overlapping transitions and low sensitivity, e.g., arising from SiO2-rich compositions with small change in heat capacity during glass transition or the low sensitivity of thermocouples at high temperature. These challenges might be overcome using temperature-modulated DSC (TM-DSC), which enables separation of overlapping signals and improved sensitivity at the expense of increased measurement duration

Parametric study of temperature-modulated differential scanning calorimetry for high-temperature oxide glasses with varying fragility

Differential scanning calorimetry (DSC) has proven to be a highly versatile technique for understanding the glass transition, relaxation, and crystallization behavior of inorganic glasses. However, the approach is challenging when probing glass samples that exhibit overlapping transitions or low sensitivity. To overcome these problems, temperature-modulated DSC (TM-DSC) can be utilized, in which a sinusoidal heating rate is superimposed on the linear heating rate known from standard linear DSC. Until recently, it has only been possible to perform TM-DSC measurements on commercial instruments at temperatures below 973 K, which is insufficient for many oxide glasses of industrial interest, particularly silicate glasses. However, recent commercially available software now enables TM-DSC measurements to be performed at temperatures far exceeding 973 K. To investigate the suitability of using TM-DSC to study glass transition and relaxation behavior in high-temperature silicate systems, we have performed systematic TM-DSC measurements on three different oxide glass systems with varying glass transition temperature and liquid fragility. We find that relatively large underlying heating rates (2–5 K/min) and modulation amplitudes (4–5 K) are needed in order to obtain data with high signal-to-noise ratios. For these combinations of experimental parameters, we also observe a linear response as found using Lissajous curves. Overall, this study suggests that TM-DSC is a promising technique for investigating the dynamics of high-temperature oxide glass systems with a wide range of liquid fragilities.</p