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Abstract

Lattice defects such as vacancies, grain boundaries and cracks are inevitably present in technical materials. In order to test microstructural effects on thermal conductivity for a broad range of interatomic bond types, several model materials: silicon with covalent bonds, calcium-fluoride with ionic bonds and copper with metallic bonds were chosen for comparison. The results show that there is a strong non-linear response of the thermal conductivity with respect to vacancy concentration in Si. Concerning grain boundaries, a sharp drop of the thermal conductivity at the interface was observed, which led to the definition of an effective interfacial thermal conductivity. Two temperature model was coupled to classical molecular dynamics simulation to considering the electronic configuration.

Keywords: thermal conductivity, vacancy, interface, density of state, two temperature model