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Full-Text Articles in Nanoscience and Nanotechnology

Effect Of Nanoparticle Additives On The Tribological Behavior Of Oil Under Boundary Lubrication, Yosef Jazaa Jan 2018

Effect Of Nanoparticle Additives On The Tribological Behavior Of Oil Under Boundary Lubrication, Yosef Jazaa

Graduate Theses and Dissertations

In this study, three different nanoparticles (CuO, WC, WS2) of comparable nominal diameter, were added to a Polyalphaolefin (PAO) base oil to evaluate tribological response in the boundary lubrication regime. The concentration of particles was fixed at 1% by weight for this study and different surfactants (Oleic acid, polyisobutylene succinimide) and dispersion methods were employed to determine the impact on agglomeration and the observed tribological response. The results showed that of the methods studied, adding 10 % Oleic acid (OA) while sonicating the particles for 30 minutes reduced the agglomeration the most and adding 1% Oleic acid while sonicating the particles ...


Solution Phase Synthesis And Computational Investigation Of Pnictide Based Nowotny-Juza Phases, Miles Arthur Burris White Jan 2018

Solution Phase Synthesis And Computational Investigation Of Pnictide Based Nowotny-Juza Phases, Miles Arthur Burris White

Graduate Theses and Dissertations

Filled tetrahedral semiconductors comprised of elements from group I, II, and V of the periodic table are of interest to the thermoelectric, photovoltaic, and battery fields due to their tunable electronic structures. However, until recently, the synthesis of these materials in a facile and scalable manner had remained elusive. In this thesis, we demonstrate the solution phase synthesis of three members of this class of compounds (LiZnP, LiCdP, and LiZnSb). Furthermore, we explore the presence of polytypism in these compounds and computationally investigate which additional phases would be expected to display polytypism. Finally, we closely investigate the phase space of ...


Bottom-Up Approach To Fabricate Nanostructured Thin Films From Colloidal Nanocrystal Precursors, Santosh Shaw Jan 2017

Bottom-Up Approach To Fabricate Nanostructured Thin Films From Colloidal Nanocrystal Precursors, Santosh Shaw

Graduate Theses and Dissertations

Control over microstructures at the nanoscale (<100nm) still seems challenging due to, among other things, the stochastic nature of nucleation in the bulk phase. The densification of assemblies of ligand-capped nanocrystals (colloidal nanocrystal assemblies, CNAs) could bypass this challenge that limits our control over the nanostructure and, therefore, the properties of materials. However, the removal of the ligands and the cracking that follows it are the two critical hurdles that have been stymieing this approach.

We show that low-pressure plasma processing can effectively remove ligands from CNAs (down to 0.6 at.% of carbon which can be accounted for adventitious carbon) without harming the properties of the inorganic cores of the nanoparticles and the structure of CNAs. The cracking of CNAs is correlated with the structure of the CNAs, which can be controlled and easily predicted by Hansen solubility parameters of solvent in which the nanoparticles are dispersed. While a fully solvated ligand shell leads to the formation of close-packed ordered CNAs – which cracked after self-assembly or ligand removal ...


Precise Control Over Morphology And Density Of Metal And Transition Metal Nanostructures For Sensing And Energy Related Applications, Minh Hoang Tran Jan 2017

Precise Control Over Morphology And Density Of Metal And Transition Metal Nanostructures For Sensing And Energy Related Applications, Minh Hoang Tran

Graduate Theses and Dissertations

Metallic nanostructures are of great interest due to their applicability in various modern technologies, such as catalysis, sensing, and optoelectronics. In this work, we employed three solution-based methods, including colloidal suspension synthesis, modified galvanic displacement, and electrodeposition, to synthesize nanostructured metals and transition metals, including gold (Au), copper (Cu), platinum (Pt), palladium (Pd), nickel (Ni), and cobalt (Co). Our focus was to establish process-structure-property relationship and explore their applicability in the field of sensing and clean energy generation. More precisely we established relationships between experimental parameters, such as temperature, applied potential, electrolyte pH, reactant concentration, additive, and the number of ...


Facile Large Scale Solution Synthesis Of Nanostructured Iron, Nickel And Cobalt Telluride And Possible Applications, Sungbum Hong Jan 2017

Facile Large Scale Solution Synthesis Of Nanostructured Iron, Nickel And Cobalt Telluride And Possible Applications, Sungbum Hong

Graduate Theses and Dissertations

Transition metal chalcogenides existing in a wide variety of stoichiometries have shown captivating electrical performances. Among them, the earth-abundance and environmental friendliness of iron (Fe), cobalt (Co) and nickel (Ni) chalcogenides have dragged scientists’ attention. Moreover, as state-of-art nanotechnology has impacted on conventional bulk technology in regard to enhancement in performance and discovery of new characteristics, it has been found that nanostructured the Fe, Co and Ni chalcogenides can be exploited for many applications such as superconductor, battery, thermoelectric materials and magnetic material, yet synthesis of these materials has been only accomplished in several milligram scales and normally involved costly ...


Dynamic Self-Assembling Dna Nanosystems: Design And Engineering, Divita Mathur Jan 2016

Dynamic Self-Assembling Dna Nanosystems: Design And Engineering, Divita Mathur

Graduate Theses and Dissertations

Over the last thirty years, DNA has proven to be a great candidate for engineering nanoscale architectures. These DNA nanostructures have been applied in areas such as single-molecular analyses, nanopatterning, diagnostics and therapeutics. One of the most commonly-used techniques to engineer DNA-based two- and three-dimensional functional nanostructures is DNA origami, wherein a long single-stranded DNA (called scaffold) is folded into a predetermined shape with the help of a set of shorter oligonucleotides (called staples). This thesis discusses a brief overview of DNA nanotechnology (design, assembly and applications) and three primary projects undertaken in the area of dynamic self-assembling DNA nanosystems ...


Mechanical Behavior Of Nanotwinned Materials-Experimental And Computational Approaches, Hakan Yavas Jan 2016

Mechanical Behavior Of Nanotwinned Materials-Experimental And Computational Approaches, Hakan Yavas

Graduate Theses and Dissertations

Nanotwinned materials exhibit high strength combined with excellent thermal stability, making them potentially attractive for numerous applications. When deposited on cold substrates at high rates, for example, silver films can be prepared with a high-density of growth twins with an average twin boundary spacing of less than 10 nm. These films show a very strong {111} texture, with the twin boundaries being perpendicular to the growth direction. The origins of superior mechanical and thermal properties of nanotwinned materials, however, are not yet fully understood and need further improvements.

The aim of this research is to develop a connected experimental and ...


Temperature-Dependent Thermal And Electrical Conduction In Metallic Nanostructures, Zhe Cheng Jan 2015

Temperature-Dependent Thermal And Electrical Conduction In Metallic Nanostructures, Zhe Cheng

Graduate Theses and Dissertations

In this work, temperature dependent electrical and thermal conduction in the bio-supported 3.2 nm-thin Ir nanofilm and individual silver nanowire are studied at reduced temperatures. For the Ir film, by studying the temperature-dependent behavior (300 K down to 43 K) of electron thermal conductivity (), we quantify the extremely confined defect-electron scatterings and isolate the intrinsic phonon-electron scattering that is shared by the bulk Ir. At low temperatures below 50 K,  of the film has almost two orders of magnitude reduction from that of bulk Ir. The film has ∂/∂T>0 while the bulk Ir has ∂/∂T <0. We introduce a unified thermal resistivity (=T/) to interpret these completely different ~T relations. It is found that the film and the bulk Ir share a very similar ~T trend while they have a different residual part (Θ0) at 0 K limit: 0~0 for the bulk Ir, and 0=5.5 mK2/W for the film. The Ir film and the bulk Ir have very close ∂Θ/∂T (75 to 290 K): 6.33×10-3 mK/W for the film and 7.62×10-3 mK/W for the bulk Ir. This strongly confirms the similar phonon-electron scattering in them. The temperature dependent behavior of the Lorenz number of the Ir film is also reported down to 10 K. Due to the strong defect-electron scattering, a very large residual electrical resistivity (1.2410-7 ·m) is observed for the film that dominates the overall electron transport (1.24~1.5510-7 ·m). The Debye temperature (221 K) of the film is found much smaller than that of bulk (308 K). This phonon softening strongly confirms the extensive surface and grain boundary electron scatterings. We find the Wiedemann-Franz Law still applies to our film even at low temperatures. The overall Lorenz number and that of imperfect structure (~2.25×10-8 W·Ω/K2) are close to the Sommerfeld value and shows little temperature dependence. This is contrast to other studied low dimensional metallic structures that have a much larger Lorenz number (3~7×10-8 W·Ω/K2). Electron tunneling and hopping in the biomaterial substrate are speculated responsible for the observed Lorenz number.

Additionally, the thermal ...


Functional Silica-Encapsulated Photoactive Nanocrystals, Chia-Cheng Lin Jan 2015

Functional Silica-Encapsulated Photoactive Nanocrystals, Chia-Cheng Lin

Graduate Theses and Dissertations

Silica-based nanocomposites with core/shell configurations have diverse functionalities and applications. We present the preparation and characterization of Co3O4/porous-SiO2 nanocomposites with the examination of their catalytic activity in the dye sensitized water oxidation reaction; a generalized methodology to prepare metal chalcogenides/pnictides with one-pot and one-step manner; the synthesis of Au/Ag/SiO2 multishell nanorods and their application as imaging probes in single particle tracking experiments.

Silica supported Co3O4 nanocomposites have recently drawn much attention due to their high catalytic ability in the water oxidation reaction. We have synthesized several Co3O4/porous silica nanocomposites to study the synergetic effects ...


Thermal Behavior Of The Stm Tip Under Laser Irradiation, Christopher G. Reilly Jan 2015

Thermal Behavior Of The Stm Tip Under Laser Irradiation, Christopher G. Reilly

Graduate Theses and Dissertations

This thesis discusses the thermal behavior of the STM tip under laser irradiation. The thermal expansion of the tip was researched with varying laser spot size, frequency, location, and power. In order to determine the thermal expansion of the STM tip, the behavior in both the time and frequency domain were investigated. By employing the FFT analysis, the noise of the thermal behavior in the frequency domain was greatly reduced when compared to the time domain behavior, allowing for higher resolution expansions. With noise reduced, a thermal expansion of 1 nm, equating to a 0.03 K average temperature rise ...


Nucleation And Growth Of Metals On Carbon Surfaces, David Victor Appy Jan 2014

Nucleation And Growth Of Metals On Carbon Surfaces, David Victor Appy

Graduate Theses and Dissertations

This thesis work presents an investigation of the basic interaction between metals and the carbon surfaces HOPG and amorphous carbon. This work was motivated by the discovery of a family of metal nanowires which grow as single crystals protruding substantially perpendicular to a substrate, where the substrate is held at elevated temperature (800-1100 K). The most prolific growth is seen for Cu on amorphous carbon substrates. The fabrication and properties of these wires have been pioneered by our collaborator, Dr. Gunther Richter, at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany. They have potential uses in nanoscale mechanical ...


Novel Silicon And Tin Alloy Nano-Particulate Materials Via Spark Erosion For High Performance And High Capacity Anodes In Lithium Ion Batteries, Emma Marie Hamilton White Jan 2014

Novel Silicon And Tin Alloy Nano-Particulate Materials Via Spark Erosion For High Performance And High Capacity Anodes In Lithium Ion Batteries, Emma Marie Hamilton White

Graduate Theses and Dissertations

The advent and popularity of portable electronics, as well as the need to reduce carbon-based fuel dependence for environmental and economic reasons, has led to the search for higher energy density portable power storage methods. Lithium ion batteries offer the highest energy density of any portable energy storage technology, but their potential is limited by the currently used materials. Theoretical capacities of silicon (3580 mAh/g) and tin (990 mAh/g) are significantly higher than existing graphitic anodes (372 mAh/g). However, silicon and tin must be scaled down to the nano-level to mitigate the pulverization from drastic volume changes ...


Multitasking Mesoporous Nanomaterials For Biorefinery Applications, Kapil Kandel Jan 2013

Multitasking Mesoporous Nanomaterials For Biorefinery Applications, Kapil Kandel

Graduate Theses and Dissertations

Mesoporous silica nanoparticles (MSNs) have attracted great interest for last two decades due to their unique and advantageous structural properties, such as high surface area, pore volume, stable mesostructure, tunable pore size and controllable particle morphology. The robust silica framework provides sites for organic modifications, making MSNs ideal platforms for adsorbents and supported organocatalysts. In addition, the pores of MSNs provide cavities/ channels for incorporation of metal and metal oxide nanoparticle catalysts. These supported metal nanoparticle catalysts benefit from confined local environments to enhance their activity and selectivity for various reactions.

Biomass is considered as a sustainable feedstock with potential ...


Rod-Like Plasmonic Nanoparticles As Optical Building Blocks: How Differences In Particle Shape And Structural Geometry Influence Optical Signal, Anthony Shawn Stender Jan 2013

Rod-Like Plasmonic Nanoparticles As Optical Building Blocks: How Differences In Particle Shape And Structural Geometry Influence Optical Signal, Anthony Shawn Stender

Graduate Theses and Dissertations

Gold nanoparticles, particularly those with an anisotropic shape, have become a popular optical probe for experiments involving work on the nanoscale. However, to carry out such delicate and intricate experiments, it is first necessary to understand the detailed behavior of individual nanoparticles. In this series of experiments, optical and electron microscopy were utilized for the characterization of individual nanoparticles and small assemblies of nanoparticles.

In the first experiment, gold nanorods were investigated. Single, isolated nanorods exhibit two maxima of localized surface plasmon resonance (LSPR), which are associated with the two nanorod axes. Upon the physical rotation of a nanorod at ...