The thermal transport properties of single-crystalline nanowires covered with amorphous shell: A molecular dynamics study

摘要

The thermal transport properties of single-crystalline nanowires (carbon nanowires (CNWs) and silicon nanowires (SiNWs)) covered with amorphous silicon shell are investigated by non-equilibrium molecular dynamics (NEMD). The thermal conductivity of SiNWscovered withamorphous silicon shell (Si/a-Si core-shellNWs) is obviously lower than that of single-crystalline SiNWs and it keeps approximately constant when the temperature exceeds a definite value for the diffusion properties of amorphous shell. It is quite different from that of singlecrystalline SiNWs whose thermal conductivity decreases significantly for relatively higher temperature. Compared to single-crystalline SiNWs, Si/a-Si core-shell NWs express stronger non-propagation, diffusion thermal transport properties. The thermal transport properties of CNWs covered with amorphous silicon shell (C/a-Si core-shell NWs) are essentially similar to that of Si/a-Si core-shell NWs. It expresses stronger nonpropagation, diffusion thermal transport properties and its thermal conductivity increases very little with the growth of length. However, its diffusion characteristics are weaker than that of Si/a-Si core-shellNWs. Generally speaking, the amorphous shell and amorphous/crystalline interface play a negative role to the thermal conductivities and an enhance role to the diffusion characteristics of single-crystalline nanowires, however, their degree of effect on different single-crystalline nanomaterials is different.