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Full-Text Articles in Nanoscience and Nanotechnology

Thermal Conductivity Of Complex Crystals, High Temperature Materials And Two Dimensional Layered Materials, Xin Qian Jan 2019

Thermal Conductivity Of Complex Crystals, High Temperature Materials And Two Dimensional Layered Materials, Xin Qian

Mechanical Engineering Graduate Theses & Dissertations

Thermal conductivity is a critical property for designing novel functional materials for engineering applications. For applications demanding efficient thermal management like power electronics and batteries, thermal conductivity is a key parameter affecting thermal designs, stability and performances of the devices. Thermal conductivity is also the critical material metrics for applications like thermal barrier coatings (TBCs) in gas turbines and thermoelectrics (TE). Therefore, thermal conductivities of various functional materials have been investigated in the past decade, but most of the materials are simple and isotropic crystals at low temperature. This is because the first-principles calculation is limited to simple crystals at ...


Shape Memorization And Reconfiguration Of Polymer Particles, Lewis Michael Cox Jan 2016

Shape Memorization And Reconfiguration Of Polymer Particles, Lewis Michael Cox

Mechanical Engineering Graduate Theses & Dissertations

Polymer particle systems have been experienced tremendous research efforts in recent years owing to their rapidly expanding applications. Improvements in synthesis methodologies have resulted in unprecedented control over the structure and chemistry of particles. In contrast to these advancements, knowledge of the experimental studies of the mechanical properties of particles remains scarce. Smart particles, specimens capable of changing shape in response to external stimuli, have specifically begun to attract attention. In this thesis two different smart particle systems capable of conforming to an infinite spectrum of user-controlled geometries are investigated: shape memory and shape reconfiguring particles.

Shape memory polymers have ...


Ultra-Thin Materials From Atomic Layer Deposition For Microbolometers, Nathan Thomas Eigenfeld Jan 2015

Ultra-Thin Materials From Atomic Layer Deposition For Microbolometers, Nathan Thomas Eigenfeld

Mechanical Engineering Graduate Theses & Dissertations

This research focuses on the incorporation of atomic layer deposition (ALD) materials into microbolometer devices for infrared (IR) imaging. Microbolometers are suspended micro-electromechanical (MEMS) devices, which respond electrically to absorbed IR radiation. By minimizing the heat capacity (thermal mass) of these devices, their performance may be substantially improved. Thus, implementing ultra-thin freestanding ALD materials into microbolometer devices will offer a substantial reduction in the overall heat capacity of the device. A novel nanofabrication method is developed to produce robust ultra-thin suspended structures from ALD generated materials including W, Ru and Al2O3. Unique aspects of ALD such as high conformality offer ...


Enhancing Phase-Change Heat Transfer With Copper Nanowire-Structured Surfaces, Qian Li Jan 2014

Enhancing Phase-Change Heat Transfer With Copper Nanowire-Structured Surfaces, Qian Li

Mechanical Engineering Graduate Theses & Dissertations

As energy consumption drastically increases in the electronics and energy conversion systems, heat dissipation becomes increasingly important for device reliability and system efficiency. Phase change heat transfer, which takes advantage of the latent heat during the phase change process, is the most promising method to efficiently remove high heat fluxes. Nano structures, which provide extended surface areas and enhanced hydrophilicity or hydrophobicity have been widely used in phase change heat transfer enhancement. Copper nanowires are one of the most promising nano structures due to ease of fabrication, controllable structure dimensions, and high thermal conductivity. In this study, the heat transfer ...


Nanowire Arrays And 3d Porous Conducting Networks For Li-Ion Battery Electrodes, Miao Tian Jan 2014

Nanowire Arrays And 3d Porous Conducting Networks For Li-Ion Battery Electrodes, Miao Tian

Mechanical Engineering Graduate Theses & Dissertations

There have been growing interests in developing high-capacity, high-power, and long-cycle-life lithium-ion (Li-ion) batteries due to the increasing power requirements of portable electronics and electrical vehicles. Various efforts have been made to utilize nano-structured electrodes since they can improve the performance of Li-ion batteries compared to bulk materials in many ways: fast electrode reaction due to the large surface area, efficient volume-change accommodation due to the small size, and fast Li-ion transport along the nanoscale gaps. Among various nanostructures, nanowire arrays present an excellent candidate for high performance lithium-ion battery electrodes, which have attracted intensive research over the past few ...


Advancing Microscope And Probe Design For Near-Field Scanning Microwave Microscopy, Joel C. Weber Jan 2014

Advancing Microscope And Probe Design For Near-Field Scanning Microwave Microscopy, Joel C. Weber

Mechanical Engineering Graduate Theses & Dissertations

In this thesis, we address the design and application of a microscope and probes for near-field scanning microwave microscopy. We provide an introduction to the development of microwave microscopy and its contributions to material metrology. In particular, we focus on its application to the study of photovoltaics. We then expand beyond these studies to the fabrication of nanowire-based probes for microwave microscopy. These probes provide avenues for advancing an array of scanning probe techniques, including continued measurements on photovoltaics with improved resolution.

To begin, we present a near-field scanning microwave microscope that has been configured for imaging photovoltaic samples. Our ...


Growth And Characterization Of Gallium Nitride Nanowire Leds For Application As On-Chip Optical Interconnects, Matt Brubaker Jan 2012

Growth And Characterization Of Gallium Nitride Nanowire Leds For Application As On-Chip Optical Interconnects, Matt Brubaker

Mechanical Engineering Graduate Theses & Dissertations

Gallium nitride (GaN) nanowires have potential as nanoscale optoelectronic building blocks that can be functionally integrated with silicon MEMS and IC devices. This dissertation presents an overview of the synthesis, characterization, and application of GaN nanowire light-emitting-diodes (LEDs) grown by plasma-assisted molecular beam epitaxy (MBE). Specifically, this research demonstrates discrete axial p-n junction nanowires that produce ultra-violet (UV) electroluminescence at ~40 nW optical power. It further demonstrates that a two-nanowire optical interconnect device can be fabricated from axial p-n junction nanowires with light-emitting and photoconductive capabilities. The nanowire structures obtained from MBE growth were found to depend sensitively on the ...


Galvanic Porous Silicon: Processing And Characterization For Nanoenergetics, Collin R. Becker Jan 2010

Galvanic Porous Silicon: Processing And Characterization For Nanoenergetics, Collin R. Becker

Mechanical Engineering Graduate Theses & Dissertations

Porous silicon (PS) is a silicon (Si) based material composed of pores with diameters ranging from several nanometers to several micrometers. Typically PS is formed by electrochemically etching a Si wafer in a hydrofluoric acid (HF) based electrolyte. This route requires a custom built etch cell and a power supply and is difficult to integrate with the batch processing techniques of conventional Microsystems fabrication. In the first part of this work, a galvanic etching approach is used to fabricate PS in which neither a power supply nor custom etch cell are required. Galvanic etching methods are developed to fabricate thick ...


Atomic Layer Deposition Enabled Interconnect And Packaging Technologies For As-Grown Nanowire Devices, Jen-Hau Cheng Jan 2010

Atomic Layer Deposition Enabled Interconnect And Packaging Technologies For As-Grown Nanowire Devices, Jen-Hau Cheng

Mechanical Engineering Graduate Theses & Dissertations

Nanowires (NWs) have attracted considerable interests in many applications due to their small size, extremely high surface-to-volume ratio, and superior material properties. They are promising material candidates as fundamental building blocks for future electronic, optoelectronic, energy, sensor, and biomedical applications. The majority of research activities have focused on the synthesis of NWs. With the advent of high-performance NWs, interconnect and packaging of NWs are becoming increasingly important for device applications. Vertical NW array devices, compared with horizontal NW configurations, are of great importance for achieving ultra-high integration density at the device level without the need of additional assembly and rearrangement ...


Nanomaterial Characterization Using Actuated Microelectromechanical Testing Stages, Joseph James Brown Jan 2010

Nanomaterial Characterization Using Actuated Microelectromechanical Testing Stages, Joseph James Brown

Mechanical Engineering Graduate Theses & Dissertations

In this work, microfabricated mechanical systems have been created in a variety of forms and operated to perform nanomaterials characterization tests. A simplified integrated test system was developed and used to collect data from a range of materials including gallium nitride nanowires. A new force estimation approach was developed which enables estimation of the forces provided by electrothermal microelectromechanical (MEMS) actuators, and with knowledge of a material specimen cross-section area, an estimation of the engineering stress within the nanomaterial specimen.

In an expanded design, a MEMS micromanipulator probe interfaced with a removable specimen holder, also known as a test coupon ...