Heat transfer is vital throughout research and industry. This thesis focuses on heat transfer in nanostructures and amorphous materials, in which the arrangement of atoms is crucial for the effectiveness of heat transport. Defects and mechanical deformations in a material which cause displacement or reconfiguration of atoms relative to that material’s “normal” or “pristine” condition can dramatically influence its heat transport efficiency. Since the 1950’s, there has been little progress in understanding the defects–thermal transport property relationship. Using novel numerical techniques and large-scale computations performed on modern supercomputers, I have studied heat transport in nanomaterials containing various defects and mechanical deformations. From the properties of atomic vibrations in my simulations, the effects these deformations have on heat transport can be deduced. Three research projects are presented in this thesis. The study of heat transport in screw-dislocated nanowires with low thermal conductivities in their bulk form represents the knowledge base needed for engineering thermal transport in advanced thermoelectric and electronic materials. This research also suggests a new potential route to lower thermal conductivity, which could promote thermoelectricity. The study of high-temperature coating composite materials helps with the understanding of the role played by composition and the structural characterization, which is difficult to be approached by experiments. The method applied in studying the composition-structure-property relationship of amorphous Silicon-Boron-Nitride networks could also be used in the investigation of various other similar composite materials. Such studies can further provide guidance in designing ultra-high-temperature ceramics, including space shuttle thermal protection system materials and high-temperature-resistance coating. The understanding of the impact of bending and collapsing on thermal transport along carbon nanotubes is important as carbon nanotubes are excellent materials candidates in a variety of applications, including thermal interface materials, thermal switches and composite materials. The atomistic study of carbon nanotubes can also provide crucial guidance in multi-scale study of the materials to enable large-scale thermal behavior prediction.
University of Minnesota Ph.D. dissertation. May 2017. Major: Mechanical Engineering. Advisor: Traian Dumitrica. 1 computer file (PDF); xiv, 145 pages.
Nano-scale Heat Transfer in Nanostructures: Toward Understanding and Engineering Thermal Transport.
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