ABSTRACT

The thermal transport of wurtzite CdSe nanowires (NWs) is studied by means of nonequilibrium molecular dynamics simulations. It is found that the length, diameter and strain can tune the thermal conductivity of CdSe NWs effectively, while the thermal conductivity exhibits insensitivity to torsion. The results indicate that the thermal conductivity of the CdSe NWs varies with the diameter approximately in the range of 13.8–17.7 W·m⁻¹·K⁻¹. The underlying mechanism is discussed by calculating the phonon power spectral density. The results show that the thermal transport is dominated by the centre atoms of NW, and high-frequency phonons contribute a lot to the thermal transport. Moreover, both tensile strain and compression strain can effectively suppress the thermal transport of CdSe NWs. The minimum thermal conductivity for the tensile strain and compression strain are 9.65 and 2.89 W·m⁻¹·K⁻¹, which are about 35% and 81% less than that of the unstrained structure.

摘要

通过非平衡分子动力学模拟研究纤锌矿 CdSe 纳米线 (NW) 的热传输。发现长度、直径和应变可以有效地调节 CdSe NWs 的热导率，而热导率对扭转不敏感。结果表明，CdSe NWs 的热导率随直径变化大约在 13.8-17.7 W·m ^-1 ·K ^-1的范围内. 通过计算声子功率谱密度来讨论潜在机制。结果表明，热传输以 NW 的中心原子为主，高频声子对热传输贡献很大。此外，拉伸应变和压缩应变都可以有效抑制 CdSe NW 的热传输。拉伸应变和压缩应变的最小导热系数分别为 9.65 和 2.89 W·m ^-1 ·K ^-1，比未应变结构的导热系数低约 35% 和 81%。