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Vacuum Consistent Electrochemistry In Ionic Liquid Combined With Oxide Epitaxy, Yuji Matsumoto

Journal of Electrochemistry

We introduce our state-of-the art of “vacuum consistent electrochemistry” to an investigation of the interfaces between oxides and ionic liquid (IL). Pulsed laser deposition (PLD) has been one of the powerful and sophisticated techniques to realize nanoscale preparation of high-quality epitaxial oxide thin films. On the other hand, electrochemistry is a simple, very sensitive, and non-destructive analysis technique for solid-liquid interfaces. To ensure the reproducibility in experiment of the interfaces of such epitaxial oxide films, as well as bulk oxide single-crystals, with IL, we employ a home-built PLD-electrochemical (EC) system with IL as an electrolyte. The system allows one to …

Selective Surface Activation And Flotation Of Pyrite For The Recovery Of Tellurium From Sulfide Tailings, Mulenga Mutema Chibesa

Masters Theses

Copper sulfide tailings from past and present mining operations are important secondary sources of critical elements such as tellurium (Te), a key component in cadmium–telluride photovoltaic solar cells. Characterization of tailing streams from copper porphyry (CP) ore flotation revealed that Te-bearing minerals are predominantly hosted in pyrite, which is usually depressed and discarded. Enhancing pyrite recovery is therefore a critical first step toward concentrating Te minerals for downstream extraction. However, pyrite flotation is often hindered by hydrophilic surface complexes formed during prior processing. This research investigated selective flotation of Te-bearing pyrite from CP tailings using micro flotation and bench-scale flotation, …

Surface Chemistry And Adsorption Mechanism Of Orfom® D8 For Cu Depression In Cu-Mo Flotation, Patrick Jeff Mensah

Graduate Theses & Non-Theses

In traditional chalcopyrite-molybdenite (Cu-Mo) flotation separation systems, inorganic depressants such as NaSH and NaCN are used to selectively depress chalcopyrite making it more hydrophilic so molybdenite can be floated and recovered. NaSH and NaCN are highly toxic, have high explosion potential, strong odor, and readily oxidize in air resulting in a high consumption rates. To control oxidation, nitrogen gas, and Nokes reagent are both necessary, making the process even more expensive. In addressing these challenges, attention is fast shifting to disodium carboxymethyl trithiocarbonate (Orfom® D8), a novel organic depressant designed to replace conventional inorganic depressants because it does not easily …

Surface Modification Of Activated Carbon From Sago Waste, Khaeriah Dahlan, Yane Oktovina Ansanay, Alda Filadelfi Runggaweri, Marlifon Merani

Journal of Metals, Materials and Minerals

In this paper, we analyzed the effect of surface modification on the surface properties of the active carbon from sago waste using varied oxidizers, namely H2O2, HNO3, and H2SO4. The ordinary active carbon has an initial surface area of 546.6 m2∙g-1, with a phenol and carboxylic functional group. The porosity, functional groups and morphological surface, together with the chemical composition of activated carbon were examined using a nitrogen adsorption-desorption through the Brunauer Emmett Teller (BET) method and the calculation of Barret-Joyner-Hall (BJH), a Fourier-transformed infrared spectroscopy, and a scanning electron microscopy with energy dispersive spectroscopy. The results found that the …

Accident Tolerant Fuels Claddings And The Evolution Of Their Surface Characteristics Under Critical Heat Flux, Rajnikant V. Umretiya

Theses and Dissertations

Enhanced Accident Tolerant Fuels (ATFs) systems for light water reactors require higher temperature oxidation resistance in steam environments than the current UO₂ – zirconium fuel system. Investigating the ATF materials’ surface properties is needed as they have evidenced to affect the Critical Heat Flux (CHF), which is an important parameter of the thermal-hydraulic performance required to provide safety margins. In this dissertation, the surface properties of FeCrAl alloys (APMT and C26M), Zircaloy-2, Zircaloy-4, and Cr-coating on Zircaloy-4 substrates produced by Physical Vapor Deposition (PVD) and Cold Spray (CS) were investigated according to their chemistry, topography, and wettability. The static …

Optimization And Longevity Of Functionalized Multi-Walled Carbon Nanotube-Enabled Membranes For Water Treatment, Madeleine Michael Isabella White

Master's Theses

Water scarcity is a growing concern at the global scale. Large scale water reuse is growing both in necessity and popularity. Before water reuse can be performed efficiently on a large scale or be used for potable supply, even indirectly, contaminants of emerging concern (CECs) will need to be treated at the full scale. Advanced oxidation processes (AOPs) are a form of advanced water treatment capable of treating a wide range of CECs. This study contributes to the growing field of AOPs and more specifically AOPs using ozone combined with functionalized multi-walled carbon nanotubes (MWCNTs). Ozonation of MWCNTs has been …

Defect Chemistry And Transport Properties Of Solid State Materials For Energy Storage Applications, Xiaowen Zhan

Theses and Dissertations--Chemical and Materials Engineering

Replacing organic liquid electrolytes with nonflammable solid electrolytes can improve safety, offer higher volumetric and gravimetric energy densities, and lower the cost of lithium-ion batteries. However, today’s all-solid-state batteries suffer from low Li-ion conductivity in the electrolyte, slow Li-ion transport across the electrolyte/electrode interface, and slow solid-state Li-ion diffusion within the electrode. Defect chemistry is critical to understanding ionic conductivity and predicting the charge transport through heterogeneous solid interfaces. The goal of this dissertation is to analyze and improve solid state materials for energy storage applications by understanding their defect structure and transport properties.

I have investigated defect chemistry of …

Studying Chromium And Nickel Equivalency To Identify Viable Additive Manufacturing Stainless Steel Chemistries, Zachary T. Hilton, Joseph William Newkirk, Ronald J. O'Malley

Materials Science and Engineering Faculty Research & Creative Works

Chromium and nickel equivalency modeling has long been used in welding to determine the weldability of steel chemistries. A study was conducted to determine the applicability of Cr-Ni modeling to the additive manufacturing process. Many AM methods involve rapid solidification of small melt pools, similar to welding. Chemistries with varying Cr/Ni ratios were selected for use in a selective laser melting process and modeled using known models. Initial results indicate that the standard "safe welding zone" may not directly apply to additive manufacturing. The capability to build with chemistries outside the weldability “safe zone” could result in improved and varied …

Computational Study Of Mos2/Hfo2 Defective Interfaces For Nanometer-Scale Electronics, Santosh Kc, Roberto Longo, Robert Wallace, Kyeongjae Cho

Faculty Publications

Atomic structures and electronic properties of MoS2/HfO2 defective interfaces are investigated extensively for future field-effect transistor device applications. To mimic the atomic layer deposition growth under ambient conditions, the impact of interfacial oxygen concentration on the MoS2/HfO2 interface electronic structure is examined. Then, the effect on band offsets (BOs) and the thermodynamic stability of those interfaces is investigated and compared with available relevant experimental data. Our results show that the BOs can be modified up to 2 eV by tuning the oxygen content through, for example, the relative partial pressure. Interfaces with hydrogen impurities as well as various structural disorders …

Microstructural Evolution During The Homogenization Heat Treatment Of 6xxx And 7xxx Aluminum Alloys, Pikee Priya

Open Access Dissertations

Homogenization heat treatment of as-cast billets is an important step in the processing of aluminum extrusions. Microstructural evolution during homogenization involves elimination of the eutectic morphology by spheroidisation of the interdendritic phases, minimization of the microsegregation across the grains through diffusion, dissolution of the low-melting phases, which enhances the surface finish of the extrusions, and precipitation of nano-sized dispersoids (for Cr-, Zr-, Mn-, Sc-containing alloys), which inhibit grain boundary motion to prevent recrystallization. Post-homogenization cooling reprecipitates some of the phases, changing the flow stress required for subsequent extrusion. These precipitates, however, are deleterious for the mechanical properties of the alloy …

Theoretical Study Of Photoelectrochemical Reactions And Ec-Sers On Spr Metallic Electrodes Of Silver And Gold, Yuan-Fei Wu, Ran Pang, Meng Zhang, Jian-Zhang Zhou, Bin Ren, Zhong-Qun Tian, De-Yin Wu

Journal of Electrochemistry

At present photoelectrochemistry has received much concern back to nanostructures of noble metals from semiconductor electrodes. This is due to the surface plasmon resonance (SPR) effect of metallic nanostructures, which can effectively convert the far-field light to the near-field light and concentrate the photonic energy to the local surface area with high energy density. Thus, the different enhancement mechanisms, such as the local optical field enhancement, the formation of light generated hot carriers (hot electron-hole pairs), or the photothermal effect, have been proposed in literatures. On the basis of the SPR enhancement effect, the surface-enhanced Raman spectroscopy (SERS) can be …

Voltammetric Investigation Of Xanthate Chemisorption On A Chalcopyrite Surface, Jesse Lynn Bowden

Graduate Theses & Non-Theses

Cyclic Voltammetry experiments have been conducted on copper, iron, and chalcopyrite (CuFeS2) and compared to mass-balanced EH-pH Diagrams. Potassium ethyl xanthate (KEX) was added to solution and additional voltammetry experiments were performed to determine the surface chemistry reactions of flotation collector in solution with these minerals. The ultimate goal of this research was to investigate the possibility of xanthate chemisorption onto the chalcopyrite mineral surface. Results of the copper mineral testing confirm previous literature studies and corroborate published isotherm data. Results of the iron mineral testing showed changes in surface reactions with the addition of potassium ethyl xanthate to solution, …

Electronic Properties Of Inp (001)/Hfo2 (001) Interface: Band Offsets And Oxygen Dependence, Santosh Kc

Faculty Publications

Using ab-initio methods, atomic structures and electronic properties of InP (001)/HfO2 (001) interface are studied within the framework of density functional theory. We examine the InP/HfO2 model interface electronic structures under varying oxidation conditions. The effects of indium and phosphorous concentrations on interfacial bonding, defect states, band offsets, and the thermodynamic stability at the interface are also investigated. The origin of interfacial gap states in InP (001)/HfO2 (001) interface are proposed, mainly from the P-rich oxides, which is validated by our experimental work. This highlights the importance of surface passivation prior to high-κ deposition based on the in situ spectroscopic …

First-Principles Investigations Of Iron-Based Alloys And Their Properties, Krista Renee Limmer

Doctoral Dissertations

"Fundamental understanding of the complex interactions governing structure-property relationships in iron-based alloys is necessary to advance ferrous metallurgy. Two key components of alloy design are carbide formation and stabilization and controlling the active deformation mechanism. Following a first-principles methodology, understanding on the electronic level of these components has been gained for predictive modeling of alloys.

Transition metal carbides have long played an important role in alloy design, though the complexity of their interactions with the ferrous matrix is not well understood. Bulk, surface, and interface properties of vanadium carbide, VC_x, were calculated to provide insight for the carbide …

Electroless And Chemical Metal Deposition On Human Tooth Enamel., Richard Doyle Christie

Masters Theses

"Initial investigations have confirmed the feasibility of depositing an adherent metal film onto tooth enamel. Such films might be used as pit and fissure sealants in preventive dentistry, with denture or orthodontic work, as an intermediate substrate with various organic or inorganic restorative materials, or other such areas. The process employs chemical solutions containing ions of the metal to be deposited and suitable reducing agent solutions.

To date, metallic copper and silver films have been plated onto teeth in vitro. The deposits are quite adherent and appear to exhibit the conductivity, crystal structure, luster, hardness, and other chemical and physical …