The low-temperature heat capacity of GeO2

Abstract
Measurements have been made, between about 1·4 and 25 K, of the heat capacity of four samples of vitreous GeO2 of widely differing oxygen deficiency and impurity content, and also of hexagonal (quartz) and tetragonal (rutile) crystal modifications of GeO2. In all cases contributions to C p in excess of the limiting long-wave elastic T 3 component have been observed. These anomalous contributions to C p are of similar magnitude in all cases and appear to be unconnected with oxygen deficiency or OH content and not to be caused primarily by transition metal impurities, even for the crystals. Their origin remains undetermined but it is suggested that this may be similar in polycrystal and glassy specimens; if this is confirmed, it would be of great significance in understanding the now well-established anomalies in glassy materials.