The effect of point defects and nanoparticles on thermal conductivity of magnesium silicide

HJ Zhang and T Zheng and B Gnade and K Cho, COMPUTATIONAL MATERIALS SCIENCE, 104, 172-176 (2015).

DOI: 10.1016/j.commatsci.2015.03.014

We compute thermal conductivity (kappa) of magnesium silicide (Mg2Si) with point defects and nanoparticles through molecular dynamics simulation. To describe an alloy with complex defect structures, the extended modified embedded atom method is utilized in this simulation study. The calculated phonon dispersion and kappa of pristine Mg2Si are in close agreement with first-principles calculations and experimental results. We compared the effect of intrinsic point defects and nanoparticles on heat transfer in Mg2Si at the same stoichiometry. We find that point defects could be more effective than nanoparticles to reduce kappa. The geometric size effect is also investigated for Mg and Si nanoparticles. Smaller Mg nanoparticles can significantly reduce kappa. However, Si nanoparticles demonstrate little size effect on kappa. Our simulation results show that phonon transport in Mg2Si has more contribution from strain scattering than mass defect scattering. These findings can provide guidance for experiments to more effectively engineer bulk Mg2Si with nanostructured defects for thermoelectric applications. (C) 2015 Elsevier B.V. All rights reserved.

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