Thermal boundary conductance across solid–solid interfaces at high temperatures: A microscopic approach

The existing theories for the thermal boundary conductance (TBC) of solid–solid interfaces lead to diverse values deviating from experimental measurements. In this paper, we propose a simple mechanism to evaluate the TBC contributed by phonons at room temperatures, where the microscopic structure of the interface layers between two dissimilar solids is treated as amorphous by taking into account the mismatches of the elastic modulus, the atomic masses, and the lattice spacing. Our theory explains well the observed magnitude of the TBCs across various solid–solid interfaces in the range from 10 7 to 10 9 W m − 2 K − 1. The coordination number density and the energy transfer coefficient across interfaces are key parameters for determining the TBCs.