Heat capacity of oxide glasses at high temperature region

Abstract

Heat capacities of vitreous silica, and some binary and ternary silicate, borate and phosphate glasses were measured in the temperature range from 300 to 840 K by ac calorimetry. Our previous study has revealed that heat capacities of oxide glasses scaled with the molar heat capacity at the Debye temperature have a similar magnitude and temperature dependence from 300 K to glass transition temperatures. On the basis of this observation, the factor effecting heat capacity was investigated by use of the three-band theory which is composed of separate contributions from one- and three-dimensional Debye model and Einstein model. We revealed that the heat capacity of oxide glass in the temperature range of measurements follows the one-dimensional Debye model and the compositional variations of heat capacity are evaluated in terms of the ionic packing ratio and the dissociation energy of oxide glass.