Abstract
The dynamical properties such as fragility, and non-Debye behavior of glass-forming materials have been studied by the frequency-dependent dynamic specific heat. Kubo’s formula on the fluctuation-dissipation theorem defines dynamic specific heat using the correlation function of enthalpy fluctuations. Dynamic specific heat is important for analyzing and understanding various relaxation processes. The dielectric relaxation is caused only by polar atomic motions, while the enthalpy relaxation is caused by total degrees of freedom of atomic motions. This chapter introduces two experimental methods to measure dynamic specific heat: (1) temperature-modulated differential scanning calorimetry (MDSC) and (2) photoacoustic spectroscopy. The experimental results of the dynamical properties of glass transitions in oxide glasses with covalent bond network structures and hydrogen-bonded glass-forming materials are reviewed.