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Understanding and Tuning Thermal Tra...

Xiong, Yucheng.

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Understanding and Tuning Thermal Transport in Nanowires and Nanoribbons.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Understanding and Tuning Thermal Transport in Nanowires and Nanoribbons./
作者:	Xiong, Yucheng.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2018,
面頁冊數:	122 p.
附註:	Source: Dissertations Abstracts International, Volume: 79-12, Section: B.
Contained By:	Dissertations Abstracts International79-12B.
標題:	Engineering. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10902208
ISBN:	9780438106345

Understanding and Tuning Thermal Transport in Nanowires and Nanoribbons.
Xiong, Yucheng.

Understanding and Tuning Thermal Transport in Nanowires and Nanoribbons. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 122 p.

Source: Dissertations Abstracts International, Volume: 79-12, Section: B.

Thesis (Ph.D.)--The Chinese University of Hong Kong (Hong Kong), 2018.

This item must not be sold to any third party vendors.

Thermal transport properties of nanowires and nanoribbons have received tremendous attention for both foundational research and practical applications such as thermoelectric energy conversion and thermal management of nanowire-based electronic devices. In general, a low thermal conductivity is desirable for improving the thermoelectric energy conversion efficiency, while a high thermal conductivity is advantageous for heat dissipation of electronic devices. Therefore, it is of great importance to understand and further tune thermal transport in nanowires and nanoribbons. In this thesis, I studied thermal transport in both inorganic and organic nanowires/nanoribbons and investigated effective strategies for tuning thermal conductivity. First, I explored to enhance thermal conductivity of inorganic InAs nanowires via sulfur passivation. By carefully measuring thermal conductivity of the same nanowire with or without sulfur passivation, I found that thermal conductivity of InAs nanowires can be enhanced by a ratio up to 159% by sulfur passivation. Current-voltage measurements were performed on both unpassivated and S-passivated nanowire segments to understand the mechanism of thermal conductivity enhancement. We observed a remarkable improvement in electrical conductivity upon sulfur passivation and a significant contribution from electrons to thermal conductivity, which account for the enhanced thermal conductivity of the S-passivated InAs nanowires. Thermal transport properties of organic nanostructures are rather different from those of inorganic nanostructures. Over my Ph.D. period, I systematically studied thermal transport in individual copper phthalocyanine (CuPc) nanoribbons as well as thermal transport through the planar contact between two CuPc nanoribbons. Our results show that thermal conductivity of single crystalline CuPc nanoribbons is drastically reduced after electron beam irradiation. Meanwhile, the temperature dependence trend of thermal conductivity is reversed, indicating that electron beam can induce a crystalline-to-amorphous transformation for single crystalline CuPc nanoribbons. Similar phenomena were observed for two-dimensional erucamide nanoribbons. Our study suggests that thermal transport properties of organic nanoribbons are very sensitive to the electron beam irradiation. In addition, I demonstrated that the contact thermal conductance per unit area (GCA) through the planar contact between two CuPc nanoribbons is on the order of 105 W/m 2-K. The measured GCA is two to five orders of magnitude smaller than the counterpart through the conventional solid-solid interface and three orders of magnitude smaller than that between multi-walled carbon nanotubes. To explore the strategy for enhancing thermal conductivity of organic nanostructures, I studied thermal transport in epoxy resin fibers prepared by an electrospinning approach. Different from inorganic semiconductor nanowires, thermal conductivity of epoxy resin fibers increases with reducing the diameter and surpasses the bulk value (0.25 W/m-K at 300 K) for the fiber with a diameter of 211 nm. The variation of thermal conductivity in epoxy resin fibers can be attributed to the microstructure change - enhanced interface phonon scattering between amorphous and crystalline regions and the enhanced alignment of the molecular chain orientation.

ISBN: 9780438106345Subjects--Topical Terms:

586835
Engineering.

Understanding and Tuning Thermal Transport in Nanowires and Nanoribbons.
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