Low-Temperature Thermal Properties Of Glass

It is a fundamental feature of amorphous materials like glasses that they exhibit a markedly different low-temperature behaviour than their crystalline counterparts in phonon-related properties. Below 1K the thermal, acoustic and dielectric properties show a characteristic temperature dependence (quasi-linear specific heat, quadratic thermal conductivity, logarithmic ultrasound velocity shift, logarithmic electric permittivity, etc) in all glasses independent of their chemical composition. These phonon-related low temperature anomalies can be explained phenomenologically by the tunneling model, which has provided a basic theoretical concept for the explanation of the characteristic features of glassy behaviours below 1K.