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arXiv 1005.4141cond-mat.mes-hallcond-mat.mtrl-sci
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碳纳米管与SiO2热耦合的频率和偏振特性

Frequency and Polarization Dependence of Thermal Coupling between Carbon Nanotubes and SiO2

Zhun-Yong Ong, Eric Pop

摘要:

我们使用平衡和非平衡经典分子动力学研究了从(10,10)CNT到SiO2衬底的热耗散。CNT-基板的热边界传导(TBC)计算从CNT-基板的温度差的弛豫时间,并从平衡时的界面热通量的时间自相关函数(格林-久保关系)。界面热流波动的功率谱和内部CNT能量分布的时间演化表明:1)热耦合由0-10 THz之间的长波长声子主导,2)高频(40-57 THz)CNT声子模式与亚40 THz CNT声子模式强耦合,和3)CNT声子和衬底声子之间的非弹性散射有助于界面热输运。我们还发现,低频纵向声学(LA)和扭转声学(TA)模式不转移能量的基板作为有效的低频横向光学(TO)模式。

英文摘要:

We study heat dissipation from a (10,10) CNT to a SiO2 substrate using equilibrium and non-equilibrium classical molecular dynamics. The CNT-substrate thermal boundary conductance (TBC) is computed both from the relaxation time of the CNT-substrate temperature difference, and from the time autocorrelation function of the interfacial heat flux at equilibrium (Green-Kubo relation). The power spectrum of interfacial heat flux fluctuation and the time evolution of the internal CNT energy distribution suggest that: 1) thermal coupling is dominated by long wavelength phonons between 0-10 THz, 2) high frequency (40-57 THz) CNT phonon modes are strongly coupled to sub-40 THz CNT phonon modes, and 3) inelastic scattering between the CNT phonons and substrate phonons contributes to interfacial thermal transport. We also find that the low frequency longitudinal acoustic (LA) and twisting acoustic (TA) modes do not transfer energy to the substrate as efficiently as the low frequency transverse optical (TO) mode.

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