Thermal transport in nanocrystalline materials

In this work, thermal transport in nanocrystalline materials is studied using large-scale equilibrium molecular dynamics simulation. Nanocrystalline materials with different grain sizes are studied to explore how and to what extent the size of nanograins affects the thermal conductivity and specific heat. Substantial thermal conductivity reduction is observed and the reduction is stronger for nanocrystalline materials with smaller grains. On the other hand, the specific heat of nanocrystalline materials shows little change with the grain size. Based on the calculated thermal conductivity, the thermal resistance at grain boundaries is calculated and found to be in the order of 10 − 9 m 2 K ∕ W . The simulation results are compared with the thermal transport in freestanding nanograins based on molecular dynamics simulation. Further discussions are provided to explain the fundamental physics behind the observed thermal phenomena in this work.