Phonon Conductivity in Single-Phase Glasses

Glass structure being amorphous, the mean free path of the phonons is limited to interatomic distances. Hence, conductivity is limited as compared to crystalline materials. 

There are three stages of the effect of temperature on the thermal conductivity of glass. From a very low value at 0 K, it increases rather rapidly as temperature is increased. After a certain increase, the value remains almost constant. At very high temperatures, it increases again rather sharply. This sharp increase is due to photon conductivity. 

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