Low-Temperature Excess Heat Capacity of Potassium Germanate Glasses

Low-temperature heat capacity of potassium germanate glasses (xK2O?(100-x)GeO2; x=0.0, 10.1, 19.0, 28.2, 39.0) (x indicates K2O mol% content) has been measured in the temperature range from 2 to 50 K with K2O content. From a result of the heat capacity Cp, it has been found that an excess heat capacity is not caused by a regular thermal motion but an interaction. In addition, it has also been found that a relationship between a maximum of reduced excess heat capacity CpT -3max and elastic modulus is dual. Moreover, a ‘hole’ model of liquid theory was applied to explain the formation of resonant mechanism. This model leads us to an idea that the excess heat capacity is described by degree of freedom of reallocated-and-isolated-structural units. Consequently, we conclude that the excess heat capacity is caused by the reallocated-main-network structure containing holes resonant with the reallocated-and-isolated-microstructural units.