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Pradhan, PujaReal Time Spectroscopic Ellipsometry (RTSE) Analysis of Three Stage CIGS Deposition by co-Evaporation
Doctor of Philosophy, University of Toledo, 2017, Physics
Spectroscopic ellipsometry (SE) is a powerful tool to characterize multilayered thin films, providing structural parameters and materials optical properties over a wide spectral range. Further analyses of these optical properties can provide additional information of interest on the physical and chemical properties of materials. In-situ real time SE (RTSE) combines high surface sensitivity with fast data acquisition and non-destructive probing, thus lends insights into the dynamics of film growth. In this dissertation, the methods of SE have been applied to investigate the growth and properties of material components used in the CIGS thin film photovoltaic technology. Examples of RTSE data collection and analyses are demonstrated for the growth of selenium (Se), molybdenum diselenide (MoSe2) and copper selenide (Cu2-xSe), used in CIGS technology which can then be applied in complete analysis of three-stage CIGS deposition by co-evaporation. Thin film Mo deposited by sputtering is the most widely used back contact for solar cells using CIGS absorbers. In this study, in-situ and real time characterization have been utilized in order to investigate the growth as well as the structural, optical, and electronic properties of Mo thin films deposited by DC magnetron sputtering at different substrate temperatures. In these studies, the surface roughness on the Mo is observed to decrease with increasing substrate temperature. The growth rate, nucleation behavior, evolution of surface roughness and development of void structures in Mo show strong variations with deposition temperature. In depth analyses of (e1, e2) provide consistent estimates of void fraction, excited carrier mean free path, group speeds of excited carriers and intrinsic stress in the films. Complementary ex-situ characterization of the as deposited Mo films included XRD, resistivity measurements by four-point-probe, SEM, and profilometry. This dissertation describes the research performed on the (In1-xGax)2Se3 (IGS) thin films with different Ga composition (x) and different IGS bulk layer thicknesses. The (e1, e2) database for IGS was obtained at 400°C by RTSE starting from films deposited by co-evaporation from fluxes of In, Ga, and Se with different x as in the stage I of three-stage co-evaporation process. The goal of this study is to develop a dielectric function database of IGS films with different x, enabling composition monitoring and thickness control during IGS deposition. RTSE has also been applied successfully in this dissertation research for real time monitoring of Cu-poor to Cu-rich and Cu-rich to Cu-poor transitions during the growth of CIGS films by three-stage co-evaporation. RTSE analyses for all three stages of CIGS growth have been presented including new results for IGS-to-CIGS conversion throughout stage II, Cu2-xSe development at the end of stage II, and Cu2-xSe to CIGS conversion in stage III. Thus, it has been demonstrated that in-situ RTSE combines high thickness, phase, and compositional sensitivity with fast non-invasive data acquisition, thus providing unique insights into the dynamics of CIGS film growth. This non-destructive, high speed capability has the potential to supplement or replace existing monitoring techniques applied for multi-stage co-evaporation of CIGS in both laboratory and industry settings. For further insights into the effect of deposition temperature on device performance, a higher than standard substrate temperature was utilized for the growth of CIGS thin films. Elevation of the substrate temperature for stage II/III deposition from 570C to 620C has led to significant improvements in the efficiency of the CIGS solar cell. The highest efficiency CIGS solar cell obtained in this study is 17.4%.

Committee:

Robert Collins (Committee Chair); Nikolas J. Podraza (Committee Member); Bo Gao (Committee Member); Jacques G. Amar (Committee Member); Dean M. Giolando (Committee Member)

Subjects:

Materials Science; Physics; Solid State Physics

Keywords:

Spectroscopic Ellipsometry; RTSE; selenium; molybdenum diselenide ; copper selenide; Molybdenum; dielectric function;three-stage Copper Indium Gallium di-selenide deposition by co-evaporation

Blumer, Ari NathanFew-layer MoS2 Flakes and Carbon Quantum Dots as Supercapacitor Electrode Materials
Bachelor of Science (BS), Ohio University, 2018, Engineering Physics
Monolayer molybdenum disulfide (MoS2) has been rigorously studied following the discovery of the first monolayer (or 2D) material, graphene, in 2004. The optical and electronic properties of monolayer MoS2 are of great interest, due to possible application in nano-scale devices such as transistors and photodetectors. In addition to these properties, monolayer MoS2 may possess the ability to contribute to pseudocapacitive redox reactions, when used as an electrode material in an electrochemical capacitor. Here, in order investigate its participation in faradaic charge transfer processes, we perform physical and electrochemical analysis of liquid-exfoliated few-layer MoS2 flakes in combination with carbon nanoparticles (a well-studied electric double-layer capacitor electrode material). Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) curves of various concentrations of MoS2/C have already shown significant pseudocapacitive properties in the exfoliated MoS2. Oxidation peaks are visible at +0.0645 V and +0.212 V vs. Ag/AgCl in 0.05 M Na2SO4, with corresponding oxidation peaks at +0.0424 V and +0.178 V. With higher concentration of MoS2, these peaks become more prominent, supporting the hypothesis that MoS2 participates in faradaic charge transfer processes. Analysis of physical interactions between MoS2 nanoflakes and carbon nanoparticles have been investigated through scanning electron microscopy (SEM), transition electron microscopy (TEM), and energy-dispersive x-ray spectroscopy (EDXS).

Committee:

Martin Kordesch, Dr. (Advisor); John Staser, Dr. (Advisor)

Subjects:

Alternative Energy; Energy; Engineering; Physics

Keywords:

Monolayer; molybdenum; molybdenum disulfide; sulfur; carbon; quantum dots; CQD; MoS2; supercapacitor; energy storage; engineering; physics

Maloy, Stuart AndrewDislocations and mechanical properties of single crystal molybdenum silicide
Doctor of Philosophy, Case Western Reserve University, 1994, Materials Science and Engineering
Dislocations and mechanical properties of single crystal MoSi2 have been investigated. Specimens were tested in compression along (001), (021), and (771) axes at strain rates of 1 × 10-4/s and 1 × 10-5/s and at temperatures ranging from 900-1600°C in vacuum or argon. The yield stress along (001) was an order of magnitude greater than that measured along (021) or (771) and along all orientations the yield stress was strongly dependent on temperature. Rate jump tests performed along (001) at 1400°C revealed that the yield stress was rate sensitive with a stress exponent of 4. The activated slip systems were determined using optical slip trace analyses and techniques in transmission electron microscopy. Slip occurred via five different slip systems (11<100>, 13<100>, 1001/2<111>, 131/2<331>, and 111/2<111>) depending on the orientation, temperature and strain rate at which each test was performed. The critical resolved shear stress was determined for the activated slip systems from the measured 0.2% yield stresses. At 900-1100°C, the lo west critical resolved shear stresses were for slip on the 11<100>, 1101/2<111> and 131/2<331> slip systems while at 1200-1600°C the lowest critical resolved shear stresses were for slip on the 11<100> and the 13<100> slip systems. Decompositions and dissociations of 1/2<331> and 1/2<111> dislocations were observed. The 1/2<331> dislocation decomposes into 1/2<111> and <110> dislocations during deformation at temperatures above 900°C. This decomposition prevents deformation by the 1/2<331> dislocation at temperatures of 1200°C and above. HREM observations of the core of a 1/2<331> dislocation revealed that it was dissociated out of the 13 glide plane after deformation at 900°C, while observations of the core of a 1/2<111> dislocation after deformation at 1100°C revealed that it was dissociated by glide in the 110 plane. These core structures strongly affect the Peierls stress for glide of the 1/2<331> and 1/2<111> dislocations. Large climb dissociations of the 1/2<111> and 1/2<331> dislocations were also observed on the (001) plane, possibly resulting from the precipitation of Si vacancies on dislocations. A detailed comparison of these results with those of Umakoshi, Sakagami, Hirano and Yamane (1990) was undertaken by testing material provided by Umakoshi along (001) at 1000, 1300 and 1400°C and along (771) at 1100°C at a strain rate of 1 × 10-5/s. Marked differences were observed and explained by the dislocation substructure observed after deformation.

Committee:

Arthur Heuer (Advisor)

Keywords:

Dislocations mechanical properties single crystal molybdenum silicide

Thompson, Loren KeithInterfacial studies of molybdenum disulfide semiconductor/electrolyte systems /
Doctor of Philosophy, The Ohio State University, 1983, Graduate School

Committee:

Not Provided (Other)

Subjects:

Chemistry

Keywords:

Molybdenum;Semiconductors;Electrolytes

Eifert, James RichardGravimetric analysis of the austenite/ferrite transformation in iron and iron-molybdenum alloys /
Doctor of Philosophy, The Ohio State University, 1973, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Chemistry;Iron alloys;Iron-molybdenum alloys

Gardner, Christopher BrentRock-Derived Micronutrient Transport across Landscape Units: Hydrologic Flow Path Analysis and Catchment-Scale Transport in the Tropics and Small Mountainous Rivers
Doctor of Philosophy, The Ohio State University, 2015, Geological Sciences
This dissertation investigates the sources, sinks, and hydrologic transport of molybdenum (Mo) in experimental watersheds in tropical Panama. The role of preferential flow paths during storm events were first investigated using germanium (Ge) and silicon (Si) as flow path tracers to examine the partitioning of precipitation event waters in catchments with different land covers. The riverine concentrations, weathering yields, and fluxes of Mo, vanadium (V), and uranium (U) were investigated in small mountainous rivers and streams draining high standing ocean islands using archived water samples. In Chapter 2 of this dissertation, three end-member water types were identified in three experimental catchments — stream baseflow (high [Si], low Ge/Si ratio), dilute event water (low [Si], moderate Ge/Si ratio), and soil pore water (low [Si], high Ge/Si ratio). A three component mixing model was employed as a hydrograph separation tool. During small rain events, storm flow is dominated by baseflow and dilute event water components. During larger events, the third shallow soil water component with high [Ge] and low [Si] is activated, reaching a maximum during the receding limb of the hydrograph. The magnitude of the increase in [Ge] in storm flow is proportional to the size of precipitation event. This component is interpreted to represent the activation of a continuum of long, preferential flow paths in the shallow soil though which event waters acquire an elevated Ge signal. In Chapter 3, the mixing model from Chapter 2 was applied to the hydrologic cycle of Mo during storm events. Though Mo is considered a rock-derived micronutrient, concentrations were higher in precipitation, canopy throughfall, and shallow soil water than in the groundwater and stream waters in contact with underlying bedrock. A simple mass balance suggests that Mo is being retained within the catchment during storm events. Three and two-component hydrograph separation models consisting of precipitation, soil pore water, and baseflow were applied to predict Mo concentrations in event flow waters resulting from the mixing of these end-members. The modeled fractions vastly over estimated observed Mo concentrations in stormflow, which were modeled better as simple dilution of stream baseflow. Selective chemical soil extractions suggest precipitation-derived Mo is associated with organic material in the soil. Chapter 4 investigates the riverine concentrations, ocean flux, and weathering yields of Mo, V, and U in a large number small mountainous rivers and streams draining high standing ocean islands. Unlike in large river systems, in which Mo is derived predominately from pyrite dissolution, dissolved Mo concentrations in these rivers do not correlate with sulfate. V correlates strongly with Si in terrains dominated by silicate rocks, but not in sedimentary regions. Fluxes of U and Mo into the ocean from igneous terrains are lower than the global average, while fluxes of V from these regions are higher, and up to two orders of magnitude higher in rivers draining young volcanics. Weathering yields of Mo and V in most regions are above the global mean.

Committee:

W. Berry Lyons (Advisor); Anne Carey (Committee Member); Yu-Ping Chin (Committee Member); John Olesik (Committee Member)

Subjects:

Geochemistry; Hydrology

Keywords:

molybdenum; vanadium; uranium; germanium; rivers; hydrograph separation; tropical hydrology; preferential flowpath, small mountainous rivers, coupled biogeochemical cycles

Gross, Carl MorrisGrowth and Characterization of Molybdenum Disulfide Thin Films
Master of Science in Electrical Engineering (MSEE), Wright State University, 2016, Electrical Engineering
Two-dimensional materials, or materials that are only one atomic layer thick, have seen much research in recent years because of their interesting electrical properties. The first of these materials, graphene, was found to have incredible electrical properties but lacked a bandgap in intrinsic films. Without a bandgap, graphene cannot create transistors that can be shut off. Molybdenum disulfide, however, is a two-dimensional semiconductor with a large bandgap. The main issue of molybdenum disulfide is that synthesized films are a much lower quality than their exfoliated counterparts. For molybdenum disulfide to be able to be used practically, a method of synthesis must be found that can reliably create quality large area monolayer films. In this thesis, three methods of molybdenum disulfide film synthesis are presented. Methods implemented used a tube furnace as a chemical vapor deposition system to evaporate source materials to synthesize thin films of molybdenum disulfide. An exploration into the different synthesis parameters shows optimal conditions for these specific methods. Then a discussion of these different methods is presented by judging films grown by using these methods on relevant criteria. This work shows methods to synthesize large area, polycrystalline, small grain, multilayer films, both intrinsic and doped, and to synthesize small area, single crystal and polycrystalline, monolayer films of molybdenum disulfide.

Committee:

Yan Zhuang, Ph.D. (Advisor); Shin Mou, Ph.D. (Committee Member); Michael Saville, Ph.D., P.E. (Committee Member)

Subjects:

Electrical Engineering; Engineering; Materials Science; Nanoscience; Nanotechnology

Keywords:

Molybdenum Disulfide; 2D Materials; Chemical Vapor Deposition; Raman Spectroscopy

Fellinger, Michael RichardFirst Principles-Based Interatomic Potentials for Modeling the Body-Centered Cubic Metals V, Nb, Ta, Mo, and W
Doctor of Philosophy, The Ohio State University, 2013, Physics
Accurate large-scale materials simulations depend crucially on high-quality classical interatomic potentials. This study constructs embedded-atom method (EAM) and modified embedded-atom method (MEAM) interatomic potentials for the body-centered cubic (bcc) metals V, Nb, Ta, Mo, and W from data generated by first-principles density-functional theory (DFT) calculations. Comparisons of a wide range of computed materials properties to DFT calculations and experimental data test the quality of the potentials. The analysis reveals that EAM and MEAM potentials generated from low-pressure DFT data accurately model many properties of the bcc metals at low to moderate pressure, but MEAM potentials generated from low- and high-pressure data are needed for quantitative high-pressure simulations. These high-pressure potentials capture much of the physics of the bcc metals at ambient conditions, produce the correct energies and geometries of multiple crystal phases, and correctly model the pressure dependence of mechanical properties. The potentials provide a reliable method for studying the deformation of bcc metals over a broad range of temperature and strain conditions, and also offer a viable starting point for constructing accurate potentials for technologically important alloys containing the bcc metals.

Committee:

John Wilkins (Advisor); Jonathan Pelz (Committee Member); Nandini Trivedi (Committee Member); Michael Mills (Committee Member)

Subjects:

Physics

Keywords:

classical; interatomic; potential; EAM; embedded atom method; MEAM; modified embedded atom method; bcc; body centered; metals; V; vanadium; Nb; niobium; Ta; tantalum; Mo; molybdenum; W; tungsten; DFT; ab initio; first-principles; modeling; force matching

Polsinelli, Gregory AnthonyBacterial generation of the anti-greenhouse gas dimethylsulfide: kinetic, spectroscopic, and computational studies of the DMSO reductase system
Doctor of Philosophy, The Ohio State University, 2008, Ohio State Biochemistry Program
The study presented herein provides a better understanding of the global sulfur cycle at the molecular level by exploring the enzymatic process whereby DMS is generated from from dimethylsulfoxide (DMSO) by examining the pathway that leads to the generation of this gas, the DMSO reductase pathway. Resonance Raman (rRaman) spectroscopic studies have also been undertaken in order to determine the roles of two active site residues, W116 and Y114, in the catalytic cycle of substrate turnover in DMSO reductase. We have found that whereas Y114F mutant forms a complex with DMSO substrate and W116F does not form the complex using multiple component analysis (MCA) and rRaman spectroscopy. The reaction mechanism of the properly redox cycled W116F form of the enzyme was determined and is reported. The physiological reductant of DMSO reductase is a pentaheme, membrane-bound c-type cytochrome protein known as DorC. The purification procedure for wild-type DorC has been successfully developed as part of this study. The limiting rate of electron transfer from DorC to DMSO reductase has been determined to be 2.66 s-1 using stopped-flow spectrophotometry and pseudo-first order reaction conditions. This experiment also yielded a Kd of 13.2 μM for binding of DorC to DMSOR. Electron paramagnetic resonance (EPR) spectroscopy has been used to analyze the possible generation of a Mo (V) intermediate and it does not appear as though a Mo (V) state is generated in the course of the reaction. Surface plasmon resonance (SPR or BIAcore) experiments have been undertaken to determine the dissociation constant (Kd) of the complex independent of electron transfer. The Kd was determined to be approximately 30 μM. This study has also produced a computational model of DorC using the computer program Rosetta. From this model, protein docking simulations have been calculated using Hex 4.5 and have produced a compelling working model for the structure of the protein complex with a specific route of electron transfer from the five heme centers of DorC and into the molybdenum center of DMSO reductase identified.

Committee:

Ross Dalbey (Advisor)

Subjects:

Chemistry, Biochemistry

Keywords:

Molybdenum; Dimethylsulfoxide; Dimethylsulfide; Cytochrome

Shook, Richard Lawrence,Displacement reactions between chromium and molybdenum dioxide in a nickel matrix /
Doctor of Philosophy, The Ohio State University, 1983, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Chromium;Molybdenum;Oxides;Nickel;Substitution reactions

Clauer, Allan H.Dislocation substructure formed during creep in molybdenum single crystals /
Doctor of Philosophy, The Ohio State University, 1968, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Molybdenum;Dislocations in crystals

Larsen, William LawrenceThe oxides and oxidation of molybdenum-nickel alloys /
Doctor of Philosophy, The Ohio State University, 1956, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Stress;Molybdenum-nickel alloys

Frock, Lynn ReneeSynthesis and Electrodeposition of Mixed Metal Trinuclear Clusters of Molybdenum and Chromium in Ionic Liquid onto a Platinum Electrode
Master of Science (MS), Wright State University, 2012, Chemistry
Electrochemical properties of [Mo3O2(O2CCH3)6(H2O)(CF3SO2H)2 and [Cr2Mo(u2-CH3COO)6(u3-O)(H2O)3][CF3SO3] in 1-ethyl-3-methylimidazolium bis(pentafluoroethanesulfonyl)-imide ionic liquid was investigated. Cyclic voltammograms using a Platinum electrode indicated deposition had occurred for the [Mo3O2(O2CCH3)6(H2O)(CF3SO2H)2 metal cluster but had not for the polynuclear complex [Cr2Mo(u2-CH3COO)6(u3-O)(H2O)3][CF3SO3]. Constant potential electrolysis of -1.23 V using a platinum foil electrode was performed. Scanning electron microscopy in combination with energy dispersion spectroscopy confirmed that deposition had occurred.

Committee:

Vladimir Katovic, Ph.D. (Advisor); David Grossie, Ph.D. (Committee Chair); David Grossie, Ph.D. (Committee Member); Suzanne Lunsford, Ph.D. (Committee Member); Vladimir Katovic, Ph.D. (Advisor)

Subjects:

Analytical Chemistry; Energy

Keywords:

Molybdenum electrodeposition

Shyu, Shin-guangSynthesis and mechanistic study of dinuclear phosphido-bridged complexes of iron, molybdenum, and tungsten /
Doctor of Philosophy, The Ohio State University, 1986, Graduate School

Committee:

Not Provided (Other)

Subjects:

Chemistry

Keywords:

Iron;Molybdenum;Tungsten;Phosphides;Complex compounds

Razmjoo Ghalaie, KhorshidEffect of potassium, sulfur, boron, and molybdenum fertilization on alfalfa production and herbage composition /
Doctor of Philosophy, The Ohio State University, 1985, Graduate School

Committee:

Not Provided (Other)

Subjects:

Agriculture

Keywords:

Fertilizers;Potassium fertilizers;Nonmetals;Molybdenum;Alfalfa;Grasses

Beauchamp, Damian RichardMolecular Engineering of Organic Photosensitizes for P-type Dye-Sensitized Solar Cells and the Immobilization of Molecular Catalyst for the Hydrogen Evolution Reaction
Master of Science, The Ohio State University, 2016, Chemistry
Solar energy has become an important component in the clean energy mix. There are several different kinds of solar cells that have been developed over decades. The focus of the first three chapters will be p-type dye-sensitized solar cells (DSSCs), which are omnipotent for obtaining high efficiency and cost effective tandem DSSCs. The efficiency of p-type DSSCs lags behind their n-type counterpart due to being less investigated. Herein, the attempts to increase performance of the p-type component via molecular engineering of organic photosensitizers is described. Through the addition of bulky hydrophobic alkyl chains performance can be enhanced, though it was found that the location of these alkyl chains is a critical factor. Additionally, by adopting a double-acceptor single-donor design, as described in chapter 3, when employing the commonly used triphenylamine donor moiety, one can simultaneously increase the molar extinction coefficient while reducing the synthetic steps yielding one the fields top performing photosensitzers. In addition to the conversion of solar energy to electrical energy, the storage of intermittent renewable energy is important. Energy can be stored mechanically (e.g. pumped hydro, fly wheels, compressed air, etc.), electrochemically (e.g. batteries and capacitors), or in chemical bonds (e.g. hydrolysis, carbon dioxide reduction, etc.). Of these methods hydrolysis to produce hydrogen has been identified as an attractive potential method. This is because hydrogen has high specific energy, can be transported, and used as a fuel in fuel cells emitting only water. The problem is industry currently employs steam-methane reforming to produce hydrogen, because catalysts currently employed for hydrolysis are expensive (i.e. noble metals) and/or unstable. Therefore finding a more abundant, lower cost, and stable catalyst which can be easily processed has been of importance. Molybdenum disulfide based catalysts have been identified as a good candidate because of their low Gibbs free energy of proton absorption. The molecular variants have the highest density of catalytically active sites, but suffer from desorption from electrode surfaces. Herein a molecular molybdenum disulfide catalyst is immobilized via polymer coordination yielding a catalytic material which can be easily processed into films via a resin. This produced stable catalytic films on electrode surfaces, which show good activity toward hydrogen evolution via water reduction.

Committee:

Yiying Wu, PhD (Advisor); James Cowan, PhD (Committee Member)

Subjects:

Chemistry; Energy; Gases; Organic Chemistry; Polymer Chemistry; Polymers

Keywords:

Solar energy, dye-sensitized solar cells, organic photosensitizers, molecular engineering, fuel cells, catalysts, Molybdenum disulfide, immobilized, polymer, hydrogen evolution, water reduction

Kothen, Charles WilliamThe high temperature heat contents of molybdenum and titanium and the low temperature heat capacities of titanium /
Doctor of Philosophy, The Ohio State University, 1952, Graduate School

Committee:

Not Provided (Other)

Subjects:

Chemistry

Keywords:

Molybdenum;Titanium

Foster, James SheridanThe thermodynamics of the rhenium-oxygen and molybdenum-oxygen systems and the defect structure of alpha tantalum pentoxide /
Doctor of Philosophy, The Ohio State University, 1964, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Thermodynamics;Molybdenum oxides;Tantalum oxides

Collins, Peter ChancellorA combinatorial approach to the development of composition-microstructure-property relationships in titanium alloys using directed laser deposition
Doctor of Philosophy, The Ohio State University, 2004, Materials Science and Engineering
The Laser Engineered Net Shaping (LENS™) system, a type of directed laser manufacturing, has been used to create compositionally graded materials. Using elemental blends, it is possible to quickly vary composition, thus allowing fundamental aspects of phase transformations and microstructural development for particular alloy systems to be explored. In this work, it is shown that the use of elemental blends has been refined, such that bulk homogeneous specimens can be produced. When tested, the mechanical properties are equivalent to conventionally prepared specimens. Additionally, when elemental blends are used in LENS™ process, it is possible to deposit compositionally graded materials. In addition to the increase in design flexibility that such compositionally graded, net shape, unitized structures offer, they also afford the capability to rapidly explore composition-microstructure-property relationships in a variety of alloy systems. This research effort focuses on the titanium alloy system. Several composition gradients based on different classes of alloys (designated a, a+b, and b alloys) have been produced with the LENS™. Once deposited, such composition gradients have been exploited in two ways. Firstly, binary gradients (based on the Ti-xV and Ti-xMo systems) have been heat treated, allowing the relationships between thermal histories and microstructural features (i.e. phase composition and volume fraction) to be explored. Neural networks have been used to aid in the interpretation of strengthening mechanisms in these binary titanium alloy systems. Secondly, digitized steps in composition have been achieved in the Ti-xAl-yV system. Thus, alloy compositions in the neighborhood of Ti-6Al-4V, the most widely used titanium alloy, have been explored. The results of this have allowed for the investigation of composition-microstructure-property relationships in Ti-6-4 based systems.

Committee:

Hamish Fraser (Advisor)

Subjects:

Engineering, Materials Science

Keywords:

combinatorial method; combinatorial approach; laser deposition; directed laser deposition; LENS; titanium; molybdenum; Ti-6-4; Ti-6Al-4V; Timetal 21S; composition; microstructure; property; relationships; neural network; fuzzy logic

Walker, Justin I.Spectroscopic Analysis of Materials for Orthopaedic and Energy Conversion Applications
Master of Science, University of Akron, 2008, Physics

X-ray photoelectron spectroscopy (XPS) and electron dispersive X-ray spectroscopy (EDS) are two complimentary techniques that are used to obtain data about the chemical and electronic states of materials. The information that XPS acquires is from the surfaces of samples, while EDS gets information from the bulk. Additionally, scanning electron microscopy (SEM) is a method to get more qualitative information about substances, by taking high magnification images.

Many materials can be analyzed using these methods, but two are detailed in this thesis: electrospun aluminum oxide doped zinc oxide (AOZO) nanofibers and cobalt chromium molybdenum (CoCrMo) metal powder particulates. AOZO nanofibers are on the forefront of material research. XPS was utilized to discover how the amount of aluminum dopant, used in fabricating the fibers, affected the fibers…#8482; conductivity. CoCrMo is used to make prosthetic implants and the elemental structure is a significant factor in determining biocompatibility. XPS and EDS data was compared to ascertain discrepancies in composition, and how that affected biocompatibility.

Committee:

Rex Ramsier, PhD (Advisor); Edward Evans, PhD (Other)

Subjects:

Physics

Keywords:

XPS; EDS; SEM; AOZO; aluminum oxide; zinc oxide; nanofiber; CoCrMo; Cobalt Chromium Molybdenum; electrospin; electrospun

Sun, YuandongREDUCED SILICA GEL FOR SILICON ANODE BASED LI-ION BATTERY AND GOLD NANOPARTICLE AT MOLYBDENUM DISULFIDE PHOTO CATALYST FOR SELECTIVE OXIDATION REACTION
Master of Science, University of Akron, 2017, Polymer Science
ABSTRACT In the recent studies, carbon-silicon based insertion anode material has shown great performance compared with conventional graphite anode of lithium ion batteries (LIB) for the high specific capacity1-3. However, there are still challenges which limits the practical utilization of the carbon-silicon anodes, such as the severe degradation of capacity. In this work, commercial silica gel micron-particles used for chromatography were adopted as starting material and treated with reduction and carbon coating processes, generating micron-sized Si-SiC-C composite anode material. This anode fabricated from cheap precursors and mild synthesis exhibited reasonable capacity and stable electrochemical performance together with graphite. The morphology and composition of the composite were characterized by scanning electron spectroscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Molybdenum disulfide (MoS2), a two dimensional material, has attracted a lot of research interests in these years4. With its large surface area and unique semi-conductor properties, we are inspired to develop MoS2 as a supporting material for the catalyst of selective oxidation reaction. Gold nanoparticles were deposited onto the exfoliated MoS2 flakes by deposition-precipitation method. The morphology of the composite was studied with TEM. Isoproponal was employed as reagent for the photocatalytic reaction catalyzed by the prepared composite catalyst. The reaction process and the final product were characterized by in-stu infrared (IR) spectroscopy and nuclear magnetic resonance (NMR).

Committee:

Yu Zhu (Advisor); Steven Chuang (Committee Member)

Subjects:

Chemistry; Energy; Physical Chemistry

Keywords:

silicon anode; lithium ion battery; molybdenum disulfide; selective oxidation reaction

Ryan, John DavidChemical Applications of Transition Metal Nanomaterials: Nanoscale Toughening Mechanism of Molybdenum Disulfide-Epoxy Nanocomposites and Mammalian Toxicity of Silver Nanoparticles
Master of Science (MS), Wright State University, 2018, Chemistry
The emerging world of nanotechnology has been of great interest within the last few decades. In this regard, nanomaterials have since been implemented in a number of commercial applications including: aerospace technology, coatings, sensors, and biomedical technology. This work aimed to elucidate upon the applications of transition metal nanomaterials in two separate experimental studies. The first of these studies involved the investigation of two-dimensional molybdenum disulfide (MoS2) nanoparticles, and their role in the toughening mechanism of epoxy composites. Two separate exfoliation techniques were implanted to target the influence surface chemistry of the nanomaterial and solvent quality had on the bulk thermal, mechanical and chemical properties of the nanocomposite system. A suite of characterization tools including UV-Vis spectrophotometry, differential scanning calorimetry, thermal gravimetric analysis, dynamic mechanical analysis, FT-IR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were executed to provide detailed information regarding property changes. In addition, a method was developed to monitor the nanoscale fracture mechanics of MoS2-epoxy nanocomposites using micro-tensile testing and SEM upon altered films. Results concluded that surface functionality of MoS2 within the studied models played a significant role in the toughening mechanism of epoxy composites. In addition, it was found that solvent quality greatly contributes to the curing behavior, as well as the chemical network formation of the material system. The second study involved a systematic investigation of the toxicity mechanism behind positively charged cetyltrimethyl ammonium bromide (CTAB)-capped silver nanoparticles (AgNPs) in Sprague-Dawley rats. To fully assess the toxic effects within the studied specimens, CTAB-capped AgNPs, as well as Ag+ and CTAB solutions were orally administered to experimental and control groups, respectively for an 18-day period. At the termination of the exposure, rats were sacrificed and tissues of interest were harvested including: the digestive gland (jejunum), liver, spleen, brain and bone (tibia). These tissues were then subjected to a panel of pathological analyses including: hematology, histology, quantification of Ag using graphite furnace atomic absorption spectroscopy (GFAAS), and bone analysis using Raman spectroscopy. Findings suggested that each chemical component of CTAB-capped AgNPs possessed a unique role in the overall toxicity, with all species causing significant alterations in the blood, tissue and bone makeup of the rat specimens.

Committee:

Ioana Pavel, Ph.D. (Advisor); Steven Higgins, Ph.D. (Committee Member); Dhriti Nepal, Ph.D. (Committee Member)

Subjects:

Chemistry

Keywords:

chemistry; nanotechnology; nanomaterials; transition metal nanomaterials; Molybdenum Disulfide-Epoxy; nanocomposites; mammalian toxicity; silver nanoparticles

Parthasarathy, T. AsuriKinetics of hydrogen attack of 2 1/4 Cr-1 Mo steel /
Doctor of Philosophy, The Ohio State University, 1984, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Chromium-molybdenum steel

Goldberg, Melvin MorrisMechanism of molybdenum oxidation in gas mixtures /
Doctor of Philosophy, The Ohio State University, 1968, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Oxidation;Molybdenum

Poerschke, David L.Mechanical Properties of Oxide Dispersion Strengthened Molybdenum Alloys
Master of Sciences (Engineering), Case Western Reserve University, 2009, Materials Science and Engineering
Lanthanum oxide dispersion strengthened (ODS) molybdenum has excellent high temperature properties but low ductility. The effect of heat treatment on the mechanical properties and formability of ODS-Mo sheet has been investigated in the temperature from 1500°C to 1800°C. Mechanical tests included three point bending, high temperature tensile testing, and hardness testing. Optical metallography, SEM, and TEM were used to evaluate the microstructure for each heat treatment condition. The 1500°C heat treatment temperature led to cracking due to incomplete transformation to a stress relieved structure. Samples treated at 1800°C produced 90° bends but the bend surfaces of samples treated for long time at this temperature were not smooth. Heat treated samples had lower YS and UTS than the as-rolled material. Grain growth along the rolling direction was faster than along transverse directions. This behavior is explained by the banding of oxide particles along the rolling direction.

Committee:

David Schwam, PhD (Advisor); John Lewandowski, PhD (Committee Member); Gerhard Welsch, PhD (Committee Member)

Subjects:

Materials Science; Metallurgy

Keywords:

molybdenum; ODS; ductility; oxide dispersion strengthening; high temperature

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