Abstract
Understanding the heat transfer through confined systems at nanometer scale is of both scientific interest and technical importance. We report in this paper, a case study on the thermal conductivity of amorphous silica nanoparticles. It is found that the solid-state thermal conductivity of amorphous silica nanoparticles is size-dependent and can be quantitatively calculated by using a phenomenological theory. The observed size effect on thermal conductivity of silica nanoparticles is however not significant, mostly due to the very small phonon mean free path of amorphous silica, l0 = 0.59 nm. It is also found that the phonon-defect scattering at the nanoparticle surfaces has a predominate effect on the involved heat transfer process. The calculated thermal conductivity of 5-nm silica nanoparticles is about 0.539 W/(mK).