Dominant role of sound velocity in the thermal conductivity of silicate glasses

Assuming that the phonon acts as the main heat carrier in silicate glasses, the thermal conductivity of glass is related to the product of volumetric heat capacity, phonon mean free path, and sound velocity. However, the dominant parameter in this relationship remains unclear. In this study, we evaluate the correlation between sound velocity and thermal conductivity for the 13 types of binary silicate glasses [i.e., M2/nO–SiO2 (M: Li, Na, Ca, or Pb; n: valence number of the M cation)] at a temperature of approximately 298 K. We find that thermal conductivity is linearly correlated with sound velocity and can be approximated as λ=3.0×10−4 ν, where ν is the sound velocity (m s−1), and λ is the thermal conductivity (W m−1 K−1). Our findings highlight the possibility of designing the thermal conductivity of silicate glasses by focusing on a single parameter (i.e., sound velocity), which can be measured and predicted using the established methodology.