Low-Temperature Heat Capacity of Vitreous Germania

Abstract

The heat capacity of a specimen of pure vitreous germania has been measured between 2.3° and 23°K. An ``excess'' heat capacity is found which is qualitatively similar to that of vitreous silica which has been widely discussed. However, in contrast to the example of vitreous silica, the heat capacity of vitreous germania at the lowest experimental temperatures is very close to that corresponding to the elastic constants. In the region just above T = 0°K, the ``excess'' heat capacities of both vitreous silica and germania can be accounted for within about the experimental error by the occurrence of small peaks in the low‐frequency part of the vibrational distribution. The ratio of the frequencies of the lowest peaks is about 3, which is very close to the ratio of the temperatures at which acoustic attenuation is observed in the two glasses. Nevertheless, a direct correlation between attenuation and ``excess'' heat capacity does not seem possible. The integrated relaxation strengths of the ultrasonic attenuation are nearly the same in the glasses but the numbers of low frequencies required to explain the initial ``excess'' heat capacities differ by a factor of about 50.