Thermal conductivity of compressed SiO2 nanoglasses. A molecular dynamics study

Abstract

Nanoglasses synthesized by consolidating amorphous nanoparticles under pressure may exhibit significantly altered properties, for example greatly improved ductility, as compared to pressure-treated bulk glasses of the same composition. In this work, using molecular dynamics simulations, we examined the relationship between thermal transport and pressure treatment parameters of silica nanoglasses. Surprisingly, within 8 and 16 GPa pressure treatment, the studied nanoglasses exhibit higher thermal conductivity than bulk glasses subjected to the same pressure protocols, despite the fact that they still have porosity. Our results indicate that overall nanoglass density is the primary factor determining the thermal conductivity while the porosity and other atomic/microstructural details do not have a negative effect on thermal transport. Our study demonstrate that such nanomaterials belong to a class of materials whose thermal properties can be tuned by engineering their microstructure with particle size and – mostly – high-pressure treatment.