Thermal conductivity of GeO2-SiO2 and TiO2-SiO2 mixed glasses

The thermal conductivities of binary mixed glasses, GeO2-SiO2 and TiO2-SiO2, have been measured. Two GeO2-SiO2 glasses measured are composed of 5 and 10 mol% of GeO2, and the one TiO2-SiO2 glass which was measured is composed of 5.7 mol% of TiO2. At temperatures below 1 K, the thermal conductivities of both types of mixed glasses have a T-1.8 dependence on temperature. The magnitude of the thermal conductivity of GeO2-SiO2 increases with increasing GeO2 concentration. The thermal conductivity of TiO2-SiO2 is higher than that of pure SiO2 at temperatures above 10 K but is smaller at lower temperatures. Al temperature between a few K to about 20 K. the thermal conductivities of GeO2-SiO2 glasses have a typical plateau while that of the TiO2-SiO2 glass has a 'shoulder'.