Thermal conduction in a densified oxide glass: Insights from lattice dynamics

Thermal conductivity is an important property of oxide glasses, but its structural origins remain largely unknown. Here, we provide detailed modal information on thermal conductivity in a calcium aluminosilicate glass by relying on recent advances in lattice dynamics methods. We probe various structural features using molecular dynamics simulations by densifying the glass at pressures up to 100 GPa and studying the vibrational, mechanical, and thermal properties. We demonstrate good agreement between these simulations and complementary experiments, both of which indicate significant pressure-induced alteration of mechanical moduli, vibrational density of states, boson peak behavior, and thermal conductivity. We also find an intriguing correlation between the boson peak frequency and the total thermal conductivity in both the current glass series and a lithium borate glass series reported in literature. This correlation scales with the Debye frequency, suggesting that both parameters are associated with the transformation of the elastic medium under pressure.