报告摘要：
Thermal conductivity due to phonons in nanostructure such as nanotube, nanowire, thin film and grapheneis very different from that in bulk materials. In the bulk material, phonons transport diffusively, thus the thermal conductivity is a constant -independence of material size and geometry. It depends only on composition of material and temperature. However, both theoretical and experimental studies in the past two decades have demonstrated that the thermal conductivity of nanostructure depends on size and geometry.
This size dependent thermal conductivity is generally attributed to the long phonon mean free path. People usually believe that when the system size is larger than the phonon mean free path, phonon undergoes a diffusive process thus the thermal conductivity becomes a finite constant.
In this talk, I will demonstrate by using the length dependent thermal conductivity of nanotubeand nanowirethat this picture is not true in low dimensional nanostructures. The thermal conductivity in such low dimensional nanostructure such as nanotubeand nanowirediverges with the system length. Moreover, we can show that this divergent thermal conductivity is related to an anomalous diffusion of phonons. Boththeoretical and experimental work will be presented.