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In a study of the low-temperature anomalies which appear in disordered solids we have measured the specific heat, thermal conductivity, thermal expansion, and dielectric dispersion for a carefully prepared series of (Si02)~"(K20)"and (Si02)~"(Na20)"glasses. Each sample had a known glass transition temperature Tg, mass density, phonon velocities, covalency, and density and concentration fluctuations. The only significant correlation occurred between the phonon mean free path and the glass-transition temperature. No explicit support was found for any model developed to explain the specific heat and/or thermal conductivity of glasses.

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The intensity and spectral distribution of light scattered by K,O-SiO, glasses (K20 content up to 40 mo%) were measured. The transverse and longitudinal sound-wave velocities and the photoelastic constants were evaluated from the results. The total intensity of the scattering (and therefore the attenuation caused by it) exhibited a minimum at a concentration of ~2 5 mol% K,O. For this composition the attenuation is of that in pure SiO,. This behavior results from the existence of anomalously small concentration fluctuations in the melt of K20.3Si0, glass. A qualitative explanation of this result, involving low-temperature immiscibility regions, is presented.