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Negative Thermophoresis in Concentric Carbon Nanotube Nanodevices
journal contribution
posted on 2016-09-14, 00:00 authored by Jiantao Leng, Zhengrong Guo, Hongwei Zhang, Tienchong Chang, Xingming Guo, Huajian GaoPositive and negative
thermophoresis in fluids has found widespread applications from mass
transport to molecule manipulation. In solids, although positive thermophoresis
has been recently discovered in both theoretical and experimental
studies, negative thermophoresis has never been reported. Here we
reveal via molecular dynamics simulations that negative thermophoresis
does exist in solids. We consider the motion of a single walled carbon
nanotube nested inside of two separate outer tubes held at different
temperatures. It is found that a sufficiently long inner tube will
undergo negative thermophoresis, whereas positive thermophoresis is
favorable for a relatively short inner tube. Mechanisms for the observed
positive thermophoresis and negative thermophoresis are shown to be
totally different. In positive thermophoresis, the driving force comes
mainly from the thermally induced edge force and the interlayer attraction
force, whereas the driving force for negative thermophoresis is mainly
due to the thermal gradient force. These findings have enriched our
knowledge of the fundamental driving mechanisms for thermophoresis
in solids and may stimulate its further applications in nanotechnology.