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Full-Text Articles in Engineering

Synthesis Of Metal Oxide Surface And Interface Arrays By A Combined Solid-Liquid- Vapor/Vapor-Liquid-Solid Approach, Alexandra J. Riddle Jan 2020

Synthesis Of Metal Oxide Surface And Interface Arrays By A Combined Solid-Liquid- Vapor/Vapor-Liquid-Solid Approach, Alexandra J. Riddle

Theses and Dissertations--Chemistry

This project was motivated by an in situ heating experiment in the transmission electron microscope (TEM) in which gold (Au) nanoparticles were observed to dissolve tin dioxide (SnO2) nanowires (NWs) under vacuum. The explanation for this observation was that the high-temperature and low-pressure environment of the TEM caused the reverse reaction of the well-known vapor-liquid-solid (VLS) method commonly used to grow NWs. In the VLS process, a metal catalyst absorbs reactant vapor until it becomes supersaturated. The precipitation of the NW occurs at the liquid-solid interface, which ceases when there is no longer reactant vapor, and the diameter of the …


Method For Production Of Germanium Nanowires Encapsulated Within Multi-Walled Carbon Nanotubes, Mark Crocker, Rodney Andrews, Arumugam Pandurangan, Dali Qian Apr 2018

Method For Production Of Germanium Nanowires Encapsulated Within Multi-Walled Carbon Nanotubes, Mark Crocker, Rodney Andrews, Arumugam Pandurangan, Dali Qian

Center for Applied Energy Research Faculty Patents

A method is provided for producing germanium nanowires encapsulated within multi-walled carbon nanotubes. The method includes the steps of performing chemical vapor deposition using a combined germanium and carbon source having a general formula of GeR(4-x)Lx, where x=0, 1, 2, or 3; R is selected from a group consisting of alkyl, cycloalkyl or aryl and L=hydrogen, halide or alkoxide and growing germanium nanowires encapsulated within multi-walled carbon nanotubes on a substrate. A reaction product of that method or process is also provided.


Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara Dec 2017

Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara

Physics and Astronomy Faculty Publications

The present study examines the interaction of hydrogen and nitrogen plasmas with gallium in an effort to gain insights into the mechanisms behind the synergetic effect of plasma and a catalytic metal. Absorption/desorption experiments were performed, accompanied by theoretical-computational calculations. Experiments were carried out in a plasma-enhanced, Ga-packed, batch reactor and entailed monitoring the change in pressure at different temperatures. The results indicated a rapid adsorption/dissolution of the gas into the molten metal when gallium was exposed to plasma, even at a low temperature of 100 °C. The experimental observations, when hydrogen was used, indicate that gallium acts as a …


Deconvolving The Steps To Control Morphology, Composition, And Structure, In The Synthesis Of High-Aspect-Ratio Metal Oxide Nanomaterials, Lei Yu Jan 2017

Deconvolving The Steps To Control Morphology, Composition, And Structure, In The Synthesis Of High-Aspect-Ratio Metal Oxide Nanomaterials, Lei Yu

Theses and Dissertations--Chemistry

Metal oxides are of interest not only because of their huge abundance but also for their many applications such as for electrocatalysts, gas sensors, diodes, solar cells and lithium ion batteries (LIBs). Nano-sized metal oxides are especially desirable since they have larger surface-to-volume ratios advantageous for catalytic properties, and can display size and shape confinement properties such as magnetism. Thus, it is very important to explore the synthetic methods for these materials. It is essential, therefore, to understand the reaction mechanisms to create these materials, both on the nanoscale, and in real-time, to have design control of materials with desired …


Nanowire Cds-Cdte Solar Cells With Molybdenum Oxide As Contact, Hongmei Dang, Vijay P. Singh Oct 2015

Nanowire Cds-Cdte Solar Cells With Molybdenum Oxide As Contact, Hongmei Dang, Vijay P. Singh

Electrical and Computer Engineering Faculty Publications

Using a 10 nm thick molybdenum oxide (MoO3-x) layer as a transparent and low barrier contact to p-CdTe, we demonstrate nanowire CdS-CdTe solar cells with a power conversion efficiency of 11% under front side illumination. Annealing the as-deposited MoO3 film in N2 resulted in a reduction of the cell's series resistance, from 9.97 Ω/cm2 to 7.69 Ω/cm2, and increase in efficiency from 9.9% to 11%. Under illumination from the back, the MoO3-x/Au side, the nanowire solar cells yielded Jsc of 21 mA/cm2 and efficiency of 8.67%. Our results demonstrate …


Nanowires, Nanowire Junctions, And Methods Of Making The Same, Charles Elijah May, Vijay Pal Singh, Suresh K. S. Rajaputra Jul 2015

Nanowires, Nanowire Junctions, And Methods Of Making The Same, Charles Elijah May, Vijay Pal Singh, Suresh K. S. Rajaputra

Electrical and Computer Engineering Faculty Patents

Disclosed is a nanostructure including a first set of nanowires formed from filling a plurality of voids of a template. The nanostructure also includes a second set of nanowires formed from filling a plurality of spaces created when the template is removed, such that the second set of nanowires encases the first set of nanowires. Several methods are also disclosed. In one embodiment, a method of fabricating a nanostructure including nanowires is disclosed. The method may include forming a first set of nanowires in a template, removing a first portion of the template, thereby creating spaces between the first set …


Copper Indium Diselenide Nanowire Arrays In Alumina Membranes Deposited On Molybdenum And Other Back Contact Substrates, Bhavananda R. Nadimpally Jan 2013

Copper Indium Diselenide Nanowire Arrays In Alumina Membranes Deposited On Molybdenum And Other Back Contact Substrates, Bhavananda R. Nadimpally

Theses and Dissertations--Electrical and Computer Engineering

Heterojunctions of CuInSe2 (CIS) nanowires with cadmium sulfide (CdS) were fabricated demonstrating for the first time, vertically aligned nanowires of CIS in the conventional Mo/CIS/CdS stack. These devices were studied for their material and electrical characteristics to provide a better understanding of the transport phenomena governing the operation of heterojunctions involving CIS nanowires. Removal of several key bottlenecks was crucial in achieving this. For example, it was found that to fabricate alumina membranes on molybdenum substrates, a thin interlayer of tungsten had to be inserted. A qualitative model was proposed to explain the difficulty in fabricating anodized aluminum oxide …


Synthesis And Characterization Of P-Type Copper Indium Diselenide (Cis) Nanowires Embedded In Porous Alumina Templates, Sri Harsha Moturu Jan 2011

Synthesis And Characterization Of P-Type Copper Indium Diselenide (Cis) Nanowires Embedded In Porous Alumina Templates, Sri Harsha Moturu

University of Kentucky Master's Theses

This work focuses on a simple template assisted approach for fabricating I-III-VI semiconductor nanowire arrays. Vertically aligned nanowires of p-CIS of controllable diameter and thickness are electrodeposited, from an acidic electrolyte solution, inside porous aluminum templates using a three electrode set up with saturated calomel electrode as the reference. AAO template over ITO-glass was used as starting template for the device fabrication. The deposited CIS is annealed at different temperatures in a reducing environment (95% Ar+ 5% H2) for 30 minutes. X-ray diffraction of the nanowires showed nanocrystalline cubic phase structures with a strong orientation in the <112> direction. …


Synthesis And Characterization Of Schottky Diodes On N-Type Cdte Nanowires Embedded In Porous Alumina Templates, Srikanth Yanamanagandla Jan 2008

Synthesis And Characterization Of Schottky Diodes On N-Type Cdte Nanowires Embedded In Porous Alumina Templates, Srikanth Yanamanagandla

University of Kentucky Master's Theses

This work focuses on the growth of vertically aligned CdTe nanowire arrays of controllable diameter and length using cathodic electro deposition in anodized alumina templates. This step was followed by annealing at 250° C in a reducing environment (95% Ar + 5% H2). AAO template over ITO-glass was used as starting template for the device fabrication. The deposited nanowires showed nanocrystalline cubic phase structures with a strong preference in [111] direction. First gold (Au) was deposited into AAO using cathodic electro deposition. This was followed by CdTe deposition into the pore. Gold was deposited first as it aids the growth …