Master of Science, The Ohio State University, 2015, Chemistry

Halide perovskites have garnered much attention in recent years as a potential material for photovoltaics, semiconductors, transparent conductors, thermistors, and electromagnetic radiation detectors. Lead halide perovskites with the formula APbX3, where A = Cs+ and X = Cl-, Br-, or I- have been shown to adopt a distorted perovskite structure (space group Pnma) with desirable band gaps and electronic properties for photovoltaic and detector applications. Experiments were conducted herein to better understand the stability limit of the lead halide perovskite structure through A-site substitution with a smaller Rb+ ion. Variable X-ray powder diffraction measurements were used to identify and characterize perovskite phase transitions at elevated temperatures for RbPbCl3, RbPbBr3, and RbPbI3, all of which form non-perovskite compounds at room temperature. Solid solutions Rb(x)Cs(1-x)PbCl3 and Rb(x)Cs(1-x)PbBr3 were synthesized as a means to stabilize the high temperature perovskite phases observed in the variable temperature experiments, and to further study the effects of octahedral tilting on the band gap of the compound. The RbPbX3 (X = Cl-, Br-, and I-) phases do not form as perovskites at room temperature, but RbPbCl3 and RbPbBr3 undergo phase transitions to perovskite structures at higher temperature. RbPbCl3 transitions first at 320 °C to a tetragonally distorted perovskite structure (space group P4/mbm) then to the cubic perovskite structure (space group Pm-3m) at 340 °C. RbPbBr3 also undergoes two phase transitions, first to an orthorhombically distorted perovskite structure (space group Pnma) at 250 °C then to a tetragonally distorted perovskite structure (space group P4/mbm) at 350 °C. Solid solutions of Rb(x)Cs(1-x)PbCl3 and Rb(x)Cs(1-x)PbBr3 resulted in a orthorhombic perovskite structure (space group Pnma) at room temperature. The orthorhombic distortion increased as the Rb+ content increased, due to increased tilting of the lead-centered octahedra. For (open full item for complete abstract)

Committee: Patrick Woodward Dr. (Advisor); Anne Co Dr. (Committee Member) Subjects: Chemistry; Inorganic Chemistry; Materials Science

Master of Science (M.S.), University of Dayton, 2024, Chemical Engineering

There is a continuous thrust for cleaner and more sustainable alternatives for energy conversion with the increasing global energy demand. Among them, photovoltaics, specifically thin film solar cells are highly promising and are one of the fastest growing clean energy technologies in the United States. This research presents the synthesis and characterization of a set of novel multinary copper chalcogenide semiconductor nanocrystals (NCs), CuZn2ASxSe4-x consisting primarily of earth-abundant elements for applications in photovoltaic devices. A modified hot-injection method was used to synthesize these semiconductor NCs containing both S and Se chalcogens. The novelty of the new semiconductor NCs lies in the incorporation of multiple cations as well as two different chalcogen anions within the crystal lattice, which is an achievement from the materials synthesis aspect. The composition-controlled optical and photoluminescence properties of the CuZn2ASxSe4-x NCs were investigated via multi-modal material characterization including x-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence spectroscopy (PL). The crystal structure, as determined from the XRD primarily consisted of the metastable wurtzite (P63mc) phase. The NCs exhibited direct band gap in the visible range that could be tuned both by varying the group III cation within the composition as well as the ratio of S/Se, based on the Tauc plot obtained from the UV-vis characterization. This work lays the groundwork for future investigations into the practical applications of copper chalcogenide NCs in solar energy conversion.

Committee: Soubantika Palchoudhury (Committee Chair); Guru Subramanyam (Committee Member); Robert Wilkens (Committee Member); Robert Wilkens (Committee Member); Guru Subramanyam (Committee Member); Kevin Myers (Advisor); Soubantika Palchoudhury (Committee Chair) Subjects: Aerospace Materials; Alternative Energy; Analytical Chemistry; Biochemistry; Chemical Engineering; Chemistry; Energy; Engineering; Environmental Science; Industrial Engineering; Information Science; Inorganic Chemistry; Materials Science; Nanoscience; Nanotechnology; Nuclear Chemistry; Nuclear Engineering

Doctor of Philosophy in Materials Science and Engineering, Youngstown State University, 2024, Materials Science

Semiconductor materials have played a huge role in advancing today's technology through the electronic and photonic devices ushered in over the years. The advancement has been driven in part by society's growing need for electronic devices capable of handling higher power, higher temperature, and higher frequency. Current research efforts are expanding to ultra-wide bandgap semiconductors such as gallium oxide Ga2O3). The principal goal of this dissertation is to obtain high quality β-Ga2O3 films with controlled conductivity by magnetron sputtering deposition. The specific objectives are the following: To grow β-Ga2O3 films on sapphire substrates (section 5.2) and on native β-Ga2O3 by rf sputtering (section 5.3), to produce doped and undoped β-Ga2O3 films (Section 5.4). Additionally, to grow Lu2O3/ Ga2O3 and B2O3/Ga2O3 alloy films on (-2 0 1) UID or Sn-doped Ga2O3 and Al2O3 substrates to tune Ga2O3 original bandgap (Section 5.5). To obtain microstructural, morphological, compositional, and optical data from XRD, AFM, SEM, EDS, and UV-Vis characterization methods for all the experiments mentioned above. From this data, correlate the effects of the varying parameters for the optimization of the films, to use the developed films to fabricate Schottky barrier diodes and proceed with the electrical characterization of the fabricated devices (section 5.6).

Committee: Tom Oder PhD (Advisor); Clovis Linkous PhD (Committee Member); Constantin Solomon PhD (Committee Member); Michael Crescimanno PhD (Committee Member); Donald Priour PhD (Committee Member) Subjects: Electrical Engineering; Engineering; Experiments; Materials Science; Optics; Physics; Technology

Doctor of Philosophy, University of Akron, 2023, Polymer Science

Nanostructured hybrid materials can be formed using self-assembling side chains grafted to a polymer backbone. Small-angle X-ray and neutron scattering (SAXS & SANS) measurements on polyisobutylene graft copolymers with side chains containing β-alanine trimer have revealed that crystalline nanodomains form by self-assembly. Modifying the side chain chemistry allows one to tailor the β-alanine nanocrystal length from over 300nm down to approximately 10nm. The degree of crowding at the nanodomain interfaces impacts the temperature dependence of the microphase separation. Chemical variations in the side chains, such as removing C18 tails and adding C11 spacers between the backbone and β-alanine trimers have dramatic effects on nanocrystal size, domain spacings, order-disorder transition temperature and width of transition, crystal melting temperature, and bulk mechanical properties. The last chapter describes progress in defining the interface morphologies in blends modified with Interfacial Supramolecular Coupling Agents (ISCAs) containing β-alanine. Polyethylene (PE) and polypropylene (PP) constitute the majority of mixed plastic waste produced globally. In the approach studied, it is envisioned that a pair of ISCAs will populate the interfaces between PE-rich and PP-rich phases and anchor the phases together. From SAXS, SANS, Wide Angle X-ray Scattering (WAXS) and Atomic Force Microscopy (AFM) analysis it is evident that the presence of ISCAs alters the crystalline structure of the overall blend.

Committee: Mark Foster (Advisor); Mesfin Tsige (Committee Chair); Bi-min Zhang Newby (Committee Member); Toshikazu Miyoshi (Committee Member); Li Jia (Committee Member) Subjects: Engineering; Materials Science; Nanoscience; Nanotechnology; Physics

Doctor of Philosophy, The Ohio State University, 2023, Electrical and Computer Engineering

Beta-phase gallium oxide (β-Ga2O3), with its ultrawide band gap energy (~4.8 eV), high predicted breakdown field strength (6-8 MV/cm), controllable n-type doping and availability of large area, melt-grown, differently oriented native substrates, has spurred substantial interest for future applications in power electronics and ultraviolet optoelectronics. The ability to support bandgap engineering by alloying with Al2O3 also extends β-(AlxGa1-x)2O3 based electronic and optoelectronic applications into new regime with even higher critical field strength that is currently unachievable from SiC-, GaN- or AlxGa1-xN- (for a large range of alloy compositions) based devices. However, the integration of β-(AlxGa1-x)2O3 alloys into prospective applications will largely depend on the epitaxial growth of high quality materials with high Al composition. This is considerably important as higher Al composition in β-(AlxGa1-x)2O3/Ga2O3 heterojunctions can gain advantages of its large conduction band offsets in order to simultaneously achieve maximized mobility and high carrier density in lateral devices through modulation doping. However, due to the relative immaturity of β-(AlxGa1-x)2O3 alloy system, knowledge of the synthesis and fundamental material properties such as the solubility limits, band gaps, band offsets as well as the structural defects and their influence on electrical characteristics is still very limited. Hence, this research aims to pursue a comprehensive investigation of synthesis of β-(AlxGa1-x)2O3 thin films via metal organic chemical vapor deposition (MOCVD) growth methods, building from the growth on mostly investigated (010) β-Ga2O3 substrate to other orientations such as (100), (001) and (-201), as well as exploring other polymorphs, such as alpha (α) and kappa (κ) phases of Ga2O3 and (AlxGa1-x)2O3 to provide a pathway for bandgap engineering of Ga2O3 using Al for high performance device applications. Using a wide range of material characterization techniqu (open full item for complete abstract)

Committee: Hongping Zhao (Advisor); Siddharth Rajan (Committee Member); Steven A. Ringel (Committee Member); Sanjay Krishna (Committee Member) Subjects: Condensed Matter Physics; Electrical Engineering; Engineering; Materials Science; Nanoscience; Nanotechnology; Physics

Master of Science, Miami University, 2023, Geology and Environmental Earth Science

Goethite (α-FeOOH) is an iron-oxyhydroxide mineral that is commonly found in soils and is of importance within the context of industrial mineralogy and aqueous geochemistry. The structure of goethite is such that vacant rows of octahedral sites form “channels” or micropores within the structure. This study aims to investigate the role these “channels” have in distributing the force induced by dynamic shock compression. Shock compression of synthetic goethite powdered samples were achieved by using an inverted shock microscope and laser driven flyer plates. With this set-up a high-energy laser shoots small aluminum discs at high velocity towards the sample causing compression upon impact. In this experiment, 25 µm aluminum flyer plates with 3.5 km/s impact velocities were used. This resulted in the production of planar shock waves of 5 ns duration in the target goethite. Subsequent investigations of the experimental change via TEM documented that crystal morphology remained unchanged, and that goethite's “bird's nest” texture was maintained. Crystal lattices showed small zones of distortion shift in peaks and the formation of hematite. XRD interestingly identifies two blunt phases: goethite and magnetite. A thixotropic-like model for accompanying shock compression is proposed to account for goethites its shock resistant behavior.

Committee: Mark Krekeler (Advisor); Claire McLeod (Committee Member); Mithun Bhowmick (Committee Member) Subjects: Geology; Mineralogy

Master of Science in Mechanical Engineering (MSME), Wright State University, 2023, Mechanical Engineering

Additive Manufacturing (AM) methods are promising in applications where complex part geometries, exotic materials and small lot sizes are required. Aerospace manufacturing stands to use AM methods extensively in the future, and frequently requires temperature- and corrosion-resistant alloy materials such as Inconel 718. However, the microstructural evolution of Inconel 718 during additive manufacturing is poorly understood and depends on part size and shape. We studied the microstructure of Inconel 718 parts manufactured by Laser Powder Bed Fusion in order to further elucidate these dependencies. Microstructural analysis, SEM imaging, EBSD scans and Microhardness testing were performed.

Committee: Henry D. Young Ph.D. (Advisor); Dino Celli Ph.D. (Committee Member); Raghavan Srinivasan Ph.D., P.E. (Committee Member) Subjects: Materials Science; Mechanical Engineering

Master of Science, University of Toledo, 2022, Mechanical Engineering

In recent years, flexible and stretchable sensors have been a subject of intensive research to replace the traditional sensors made up of metal and semiconductors. This thesis has been conducted with the objective of exploring the possible applications of Graphene/PVDF nanocomposite in various kinds of flexible sensors as a potential sensing material. Initially, graphene/PVDF nanocomposite was synthesized by the solution-phase mixing method. A thin film of 20-22 μm was coated on a glass substrate to investigate the characteristics of the composite by using XRD and SEM techniques. This nanocomposite was best suited for piezoresistive-based sensors where the sensor senses the external stimuli and outputs the response in terms of change in electrical properties such as resistance, voltage, or current. The synthesized graphene/PVDF nanocomposite was coated on different kinds of substrates to make three different kinds of flexible sensors. They are airflow sensor, knittle pressure sensor, and accelerometer. The airflow sensor was designed and fabricated by applying a thin film of nanocomposite on the polyethylene (PE) substrate and placed inside a PVC pipe at an angle to the central axis of the pipe. The response of the sensor was tested by passing air at various speeds and recorded in terms of resistance change. The linearity and repeatability of the curves were observed. Temperature dependence on electrical conductivity was studied by heating and cooling the sample between room temperature and below the melting point of PVDF. Further, the sensing characteristics were simulated using COMSOL Multiphysics software, and the modeled data were compared with the experimental result. Another application of our in-house fabrication with the use of the nanocomposite is a knittle pressure sensor. The primary purpose of developing knittle pressure is to monitor health by either attaching to the skin or using it inside the health monitoring device. The use of fabric substrate a (open full item for complete abstract)

Committee: Ahalapitity Jayatissa (Advisor) Subjects: Mechanical Engineering

Doctor of Philosophy, University of Akron, 2021, Mechanical Engineering

In 2016 it was estimated that corrosion related costs were 3.4% of global GDP. Coatings are widely used for preventing or controlling corrosion. However, none of the currently used corrosion resistant coatings provides enough wear resistance for gears and bearing applications. Poor surface morphology of the corrosion resistant coatings cause increased wear and friction, resulting in early failure of the rolling element. Developing electrodeposited alloy coatings that promote synergy with additives used in gear and engine oils, while providing corrosion resistance can be a viable solution. Alloyed metals provides superior properties (like hardness, physical, chemical, magnetic) compared to pure metals, even at a nanoscale. Ni-W alloy was recently been reported to have unique contribution to mechanical, tribological and corrosion resistant performance. In addition, Ni was found to promote the formation of a thicker and durable lubricating layer. However, careful evaluation of in-service life of these alloy coatings are needed. Composite nanoparticles in many cases can also improve tribological performance of the component. Researchers have studied the effect of such nanoparticles on the tribological performance of oils. Both beneficial and detrimental effect of such nanoparticles has been reported. In this study NiW alloy and NiW-TiO2 composite coatings were electrodeposited on SAE 52100 steel coupons. Pulsed reversed current (PRC) electrodeposition technique is used due to its capability of producing more dense and uniform coating. Also, incorporating TiO2 nanoparticles on the NiW matrix is hypothesized to enhance the hardness and corrosion resistance. Both NiW alloy and NiW-TiO2 coated disks were tested in fully formulated oil and mineral oil provided by John Deere. Tribological performance was evaluated in both sliding and rolling condition. Corrosion resistance property were measured in 3.5% NaCl. Sliding performance were tested using High Frequency Reciproc (open full item for complete abstract)

Committee: Gary L. Doll (Advisor); Gregory N. Morscher (Committee Member); K.T. Tan (Committee Member); Rajeev K. Gupta (Committee Member); Robert Mallik (Committee Member) Subjects: Chemistry; Materials Science; Mechanical Engineering

Doctor of Philosophy (PhD), Ohio University, 2020, Chemical Engineering (Engineering and Technology)

The produced fluids from oil and gas wells usually contain a considerable amount of carbon dioxide (CO2). Although CO2 itself is not a corrosive agent, its hydrated form, carbonic acid (H2CO3) is involved in corrosion processes. CO2 corrosion, also known as “sweet corrosion”, is by far the most common type of corrosion encountered in upstream pipelines of the oil and gas industry. Despite its susceptibility to corrosion, low carbon steel (mild steel) is widely used in the oil industry because of its availability and cost-effectiveness. Understanding the corrosion behavior of mild steel in oilfield conditions and applying appropriate mitigation programs are crucial to enhance the lifespan of upstream infrastructures. Iron (II) carbonate (FeCO3) is the main corrosion product in CO2 corrosion of mild steel. An FeCO3 layer can protect the steel from rapid corrosion by acting as a diffusion barrier to relevant species for cathodic reactions and by covering portions of the steel surface and retarding the iron dissolution (anodic) reaction. The aqueous phase co-produced with the hydrocarbon phase, known as “brine”, usually contains a high concentration of calcium ions (Ca2+) and magnesium ions (Mg2+). Ca2+ and Mg2+ can incorporate into the FeCO3 lattice and form a substitutional solid solution with different physiochemical characteristics compared to pure FeCO3. This phenomenon happens because FeCO3 (siderite), CaCO3 (calcite), and MgCO3 (magnesite) share the same hexagonal crystal structure. Over the past decades, mechanisms of CO2 corrosion of mild steel and the characteristics of its corrosion products (FeCO3 and Fe3C) have been intensively studied and documented by different researchers. However, most of these studies have been performed in various dilute solutions of sodium chloride (NaCl), while Ca2+ and Mg2+ are also present in most geological formations. Additionally, the limited available literature is contradictory about the true effect of Ca2+ and Mg2+ (open full item for complete abstract)

Committee: Marc Singer (Advisor); Srdjan Nesic (Committee Member); Jason Trembly (Committee Member); Travis White (Committee Member); Lauren McMills (Committee Member); David Young (Committee Member) Subjects: Chemical Engineering; Materials Science

Master of Science, Miami University, 2019, Chemistry and Biochemistry

Decavanadates, a type of oxovanadate containing the decavanadate anion, [V10O28], were prepared using different starting materials for analysis with 51V NMR, to study how the decavanadate anions behave over time immediately following their dissolution. The different decavanadate crystal samples were produced using the starting materials KVO3 and V2O5 before being dissolved in a deuterated solvent for NMR. The changes observed in the 51V NMR spectra, along with observations of the samples during production, indicate noticeable differences between the decavanadates grown using KVO3 and those prepared using V2O5. Peak shifting was observed in the 51V NMR data, along with the appearance of different vanadate species, as time progressed. Analysis of the samples using other methods such as UV-visible spectroscopy, MS, and XRD supported conclusions based on the NMR data. Understanding how the decavanadate anions changed in solution over time, and the potential causes for observed changes gives insight into the natural processes involved in the ephemeral crystallization of decavanadate minerals and associated transport of V in natural systems.

Committee: David Tierney (Advisor); John Rakovan (Committee Member); Neil Danielson (Committee Member); Scott Hartley (Committee Member) Subjects: Chemistry

Master of Science, The Ohio State University, 2019, Food Science and Technology

This study investigated the presence of volatile and non-volatile compounds in canned processed tomatoes and how these compounds interacted with the Bisphenol A free epoxy-based lining of the cans to cause corrosion of the base metal and the migration of iron and tin compounds to the tomatoes. The tomatoes tested in this study were the Roma variety. They were sorted, washed, diced, and sealed in two-piece tinplated metal cans. These were processed by retorting at 250°F for 30 minutes then stored at 49°C for up to 50 days. Control samples were packaged and processed in glass jars. The presence and concentrations of the volatile and non-volatile compounds in the processed and unprocessed tomatoes were tested using Selected Ion Flow Tube – Mass Spectrometry (SIFT-MS) and Ion Chromatography – Mass Spectrometry (IC-MS) respectively. After removing the processed tomatoes from the cans, the linings were removed and analyzed for the volatile and non-volatiles as was mentioned before. Scanning Electron Microscopy (SEM) paired with Energy Dispersive X-ray Spectroscopy (EDS) was used to confirm the presence of visual corrosion in the processed cans and to analyze its elemental composition. X-ray Diffraction (XRD) and Fourier Transform – Near Infrared (FT-NIR) was used to characterize changes to the polymeric morphology of the can lining after the retort processing. Also, Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) was used to determine the rate and level of tin and iron migration from the metal can to the tomato product. The results of the SIFT analyses showed that the formation of dimethyl sulfide and other sulfide compounds in the tomatoes resulted from the thermal degradation of methyl methionine. These compounds diffused from the tomatoes to the lining of the cans and the XRD and FT-NIR analyses showed that they interacted with the polymer and led to the reformation of the oxirane ring of the epoxy and binding of water with the polymer lining. The (open full item for complete abstract)

Committee: Melvin Pascall (Advisor); Gerald Frankel (Committee Member); John Litchfield (Committee Member) Subjects: Food Science; Packaging

Master of Science (MS), Ohio University, 2019, Civil Engineering (Engineering and Technology)

This thesis evaluates natural and chemically stabilized subgrade soils from five project sites throughout Ohio. Three of the five project sites were historically known to have moderate to high sulfate concentrations in the natural soils (DEF-24-2.67-W, LAK- 2-7.76-W, MRW-71-3.17-N), while the other two sites were known to have little to no sulfate levels (CLA-70-13.98-W, CLI-73-6.52-E), and were used as controls. The main objective of the study was to compare in-situ and laboratory test results to determine if there were formations of ettringite or thaumasite in the soil, which can lead to sulfate heave and premature failure of pavement. Several field tests were performed such as PSPA, FWD, LWD, DCP, and SPT. Standard soil tests were performed on natural and chemically stabilized samples, such as gran size analysis, Atterberg limits, organic content, moisture content, and pH, as well as a chemical analysis comprising of neutralization potential, sulfate concentration, and X-ray diffraction (XRD). Analysis showed no major differences of moduli for pavement or soil layers between control and non-control. Results showed that sites where sulfates were known to exist, the chemically stabilized layers had sulfate concentrations greater than 3000 ppm and the pH was just barely greater than 10, which is an indication of concern for ettringite and thaumasite formation. However, the chemical analysis did not indicate formation of either mineral, therefore all conditions were not met.

Committee: Issam Khoury (Advisor) Subjects: Civil Engineering; Geotechnology; Soil Sciences

BS, Kent State University, 2018, College of Arts and Sciences / Department of Earth Sciences

Abandoned coal mines are common throughout the Appalachian region of the United States as surface and underground mines. The exposed mine waste from mining operations has led to the contamination of multiple streams throughout the region with acid mine drainage (AMD). The AMD at these sites is caused by the oxidation of the iron sulfides (pyrite, mracasite, etc.) within the coal mine waste. Associated with the AMD, heavy metals and metalloids such as As, Se, Co, Cd, Ni, Mn, Mg, Pb, and Zn are released into these streams. These can lead to associated water quality issues for drinking water and local environments near abandoned coal mine sites.The research conducted here seeks to better define the nature of the iron sulfides in coal mine waste and to demonstrate a method to observe and analyze the mineralogical transformations of iron oxides from ferrihydrite to hematite that occur in AMD settings at abandoned coal mines in the Huff Run Watershed. We use a combination of x-ray diffraction (XRD) and scanning electron microscopy (SEM) to determine the mineralogical differences between the coal shale parent material and the soils developing on the coal mine waste, the crystal form of the iron sulfides within the coal shale parent material, and the mineralogical transformations of the subsequent iron oxides as a result of dry heating. We determine that pyrite is not a primary constituent of the bulk mineralogical phases picked up by XRD in the the soils developed on the coal mine spoil although present as a bulk mineral phase in the coal shale parent material, and the method of dry heating iron oxides to simulate the mineralogical transformations over time is hindered by a persistence of ferrihydrite at high temperature ranges. From this, implications on the rate of oxidation of pyrite in these soils and the release of heavy metals and metalloids can be further inferred.

Committee: David Singer Dr. (Advisor); Alison Smith Dr. (Committee Member); Christopher Fenk Dr. (Committee Member); Elizabeth Herndon Dr. (Committee Member) Subjects: Environmental Geology; Environmental Science; Geology

Doctor of Philosophy, Miami University, 2016, Chemistry and Biochemistry

Liquid Crystals (LCs) have unique optical and physical properties that have been thoroughly investigated in the last century. The calamitic and discotic mesogens, two subclasses of LCs, are widely-known and studied in this field. A lesser-known and understudied class of liquid crystals, the sanidic mesogens, are board-like hybrids that combine properties between calamitics and discotics. This dissertation will focus on the synthesis, characterization and physical behavior of board-like and thermotropic sanidic liquid crystals. A series of alkoxy- and alkyl-substituted dibenzonaphthacene (DBN) liquid crystals were synthesized and their liquid crystal properties were analyzed. These molecules exhibit thermotropic LC phases. The phase behavior of binary alkoxysubstituted DBN mixtures was explored. Certain alkyl-substituted DBN molecules exhibit a novel thermotropic LC phase, namely, the hexatic-B phase (SmBhex). Extending the core of the DBN with the intent of observing LC phases by synthesizing a tetrabenzanthanthrene (TBAA) core with analogous substituents was attempted. The outcomes of those experiments will also be discussed.

Committee: Scott Hartley (Advisor); Richard Taylor (Committee Member); Dominik Konkolewicz (Committee Member); David Tierney (Committee Chair); Jason Berberich (Committee Member) Subjects: Chemistry; Materials Science; Organic Chemistry; Physical Chemistry

Doctor of Philosophy, The Ohio State University, 2016, Chemical Engineering

A hydrothermally stable dual-catalyst aftertreatment system for emission control of nitrogen oxides (NOx) with lower hydrocarbons (CHx) has been developed for natural gas-fired stationary lean-burn engines. The dual-catalyst system consists of a physical mixture of a reduction catalyst, palladium supported on sulfated zirconia (Pd/SZ) and an oxidation catalyst, cobalt oxide supported on ceria, CoOx/CeO2. The multifunctional aftertreatment system oxidizes nitric oxide (NO) to nitrogen dioxide (NO2), reduces NO2 to nitrogen (N2), and oxidizes carbon monoxide (CO) and the unutilized hydrocarbons. For practical applications in environmental catalysis, the catalytically active powder catalyst needs to be wash-coated onto a monolith core. To prevent permanent loss of activity due to physical separation of the wash-coat from the walls of the monolith core, adhesivity enhancing materials (binders) are added to the wash-coat. A novel method of incorporating binder to the active catalyst in situ during sol-gel synthesis is presented in this work. Alumina binder incorporated into Pd/SZ in situ during sol-gel synthesis was chosen for further development of a catalytically active washcoat based on activity tests under simulated engine-exhaust conditions. The alumina binder-incorporated Pd/SZ catalyst slurry controlled at pH 1 and calcined at 700oC demonstrated the most promising NOx reduction and CH4 oxidation activity. Cyclic thermal shock tests demonstrated enhanced adhesive properties of the wash-coat to the walls of the cordierite monolith core. Thus, a catalytically active wash-coat with superior adhesive properties was developed for practical application in a real-world aftertreatment unit. The effect of in situ incorporation of alumina to Pd/SZ during sol-gel synthesis on the structural, textural and chemical properties of the resulting catalyst was investigated as these properties significantly influence the catalytic activity of the resulting catalyst. The format (open full item for complete abstract)

Committee: Umit Ozkan PhD (Advisor); Andre Palmer PhD (Committee Member); Kurt Koelling PhD (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2016, Materials Science and Engineering

Magnesium diboride (MgB2) is a material with a superconducting transition temperature of 39 K. Discovered in 2001, the relatively large coherence length (and associated lack of weak links) together with its simple binary composition (making phase pure formation relatively easy) have made it a material of substantial interest. However, its inadequate in-field performance limits the high field applications. Chemical doping is the key to increasing the Bc2 of MgB2. Chemical doping aiming at Mg site or B site substitution is of interest and both routes are explored in this thesis. Structure-property correlations are developed for dopants that either do or do not, incorporate themselves into the MgB2 matrix. First, the effects of C doping in the state of art MgB2 wires were investigated. In order to do so, a series of state of the art C doped MgB2 wires, in both mono-filamentary and multi-filamentary forms, were fabricated by a local company. Their transport and magnetic performance in various magnetic fields, and mechanical induced degradation, were examined. The C doping influence on the critical current density and the n-values were discussed. Secondly, the effects of rare earth oxide (REO) doping in MgB2 were studied. Two sets of samples including both bulk samples and wires were fabricated. Microstructural evidence obtained by SEM and TEM proved that nano-size inclusions formed after REO doping acted as grain growth inhibitors, as evidenced a reduction of MgB2 grain size in REO doped bulk samples. The results of XRD and magnetic measurements on the bulk samples demonstrated that Dy2O3 and Nd2O3 do not alloy with MgB2, no changes being observed in the lattice parameters, Tc and Bc2 of doped MgB2. Enhancements in flux pinning and Jc were obtained in both bulk samples and wires by REO doping, consistent with the microstructural evidence of notable grain refinements and the presence of nano-size inclusions as new pinning sites in MgB2 grains. Lastly, a set of metal d (open full item for complete abstract)

Committee: Michael Sumption (Advisor); Patricia Morris (Committee Member); Roberto Myers (Committee Member) Subjects: Electromagnetics; Electromagnetism; Engineering; Materials Science; Metallurgy; Physics

Master of Science (MS), Bowling Green State University, 2016, Geology

The oil and gas booms of the late 19th century left tens of thousands of wells in Wood County, Ohio abandoned and improperly capped. This allows hydrocarbons to seep into the surrounding soil. Detection of these wells proves difficult because many of the wells are buried and their locations lost. To be able to detect the oil wells over large areas, different remote sensing techniques can be used to detect changes in soil properties caused by the presence of hydrocarbons. However, the capability of this technology depends on spatial and spectral resolution of a sensor and in situ data are often necessary. In this study, in-situ hyperspectral reflectance data and thermal imaging are used in conjunction with clay mineral X-ray diffraction analysis to identify soil properties around abandoned wells located in an agricultural area in Wood County, Ohio. This study is confirmation of previous finding and it serves to indicate uncertainties related to a limited sampling effort, and to address the importance of field sampling strategies and adequate remote sensing techniques. Non-commercial satellite based remote sensors of medium, spatial resolution, such as Landsat, are inadequate for detection of the small abandoned wells in Wood County, Ohio. In situ hyperspectral reflectance measurements, used to simulate WorldView-3 spectral and spatial resolution, suggest that this high spatial resolution commercial satellite is optimal for detecting small abandoned oil wells. It is confirmed that a spectral band ratio in the spectral range between 2.185-2.225 µm and 2.295-2.365 µm (WorldView-3 shortwave bands 6 and 8, respectively) is effective. The clay mineral X-ray diffraction analysis suggests that these changes in the spectral information occur predominately due to the hydrocarbons; clay mineral content changes in the soil did not affect the soil spectral signature to a greater extent. Thermal imaging identified higher surface temperatures in soil with higher hydrocarbon content (open full item for complete abstract)

Committee: Anita Simic (Advisor); Jeff Snyder (Committee Member); John Farver (Committee Member) Subjects: Geology; Remote Sensing

Master of Sciences (Engineering), Case Western Reserve University, 2016, Materials Science and Engineering

Alternative technologies are developing to replace rare-earth permanent magnets because of high costs and limited supply. Rare-earth permanent magnets currently are used in electric-vehicle motors and wind turbines because of their high saturation magnetization and high coercivity. Iron-nitrogen magnets (Fe16N2) with possible giant magnetization, can be a promising candidate for replacing rare-earth permanent magnets. In this study, during nitridation experiments which have been carried out by Z.Feng according to Jack's route, nitrogen austenite formed by nitriding the AHC 100.29 (a-Fe) powders with a gas mixture of 0.11NH3/ 0.89 H2 for 3600s (1h) at 923.15K in a designed nitriding reactor. The nitrided sample containing nitrogen austenite is cryomilled by ball milling the powder at liquid nitrogen temperature for 600s (10 min) at 30 Hz frequency in order for the transformation from nitrogen-austenite to nitrogen martensite to take place, and finally the sample is heat-treated for 7200s (2h) at 403.15K in order to form an ordered nitrogen martensite (Fe16N2) phase with possible giant magnetization. Various characterization techniques, such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and vibrating sample magnetometer (VSM) analysis by S.Lan, have been applied to precisely characterize these samples. Nitrogen austenite with the lattice expansion of 2.3% and the nitrogen content of (9.8±0.4) at.% formed by nitriding the AHC 100.29 (a-Fe) powders. Formation of a small fraction of coherent needle-shaped nitrogen martensite precipitations with possible preferred Nishiyama-Wasserman orientation relationship to the expanded austenite matrix and local rearrangement of nitrogen atoms in small parts of formed precipitations have been observed. Around 90% of the nitrogen austenite transformed into nitrogen martensite with lath-shaped morphology after cryomilling, while around 9% of the nitrogen austenite re (open full item for complete abstract)

Committee: Frank Ernst (Advisor); David Matthiesen (Committee Member); Peter Lagerlof (Committee Member) Subjects: Materials Science

Master of Science (MS), Ohio University, 2016, Mechanical Engineering (Engineering and Technology)

Boiler scale on waterside heat transfer surfaces poses a major operating challenge for Steam-Assisted Gravity Drainage (SAGD) operations used in the production of bitumen since produced water, which is high in total dissolved solids, is recycled. Scale from deposition of dissolved solids acts as a thermal insulating layer, decreasing heat transfer and lowering boiler efficiency. Understanding scale deposit composition on heat transfer surfaces is beneficial in the determination of adequate boiler maintenance practices and operating parameters. This research determined the effect of feedwater pH (7.5, 9, and 10) on scale composition resulting from deposition of dissolved solids under commercially relevant boiler operating conditions at 1,300 psig. Deposited phases were analytically investigated using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS), X-ray powder diffraction (XRD), and Raman spectroscopy. In addition, a thermodynamic equilibrium model to predict scale formation rate and composition was developed using HSC Chemistry. At feedwater pH values of 7.5 and 9, anhydrite (CaSO4), xonotlite (Ca6Si6O17(OH)2), and pectolite (NaCa2Si3O8(OH)) were detected. At pH 10, xonotlite and pectolite were identified in the absence of anhydrite. Furthermore, a calcium silicate phase, presumably serpentine (3MgO·2SiO2·2H2O), was identified under all operating conditions by EDS analysis only. The equilibria model predicted anhydrite as the dominant phase under each operating condition, although the amount which formed decreased as pH increased. Xonotlite was not thermodynamically favored to deposit under any operating conditions.

Committee: Jason Trembly PhD (Advisor); David Young PhD (Committee Member); Frank Kraft PhD (Committee Member); Shadrick Paris PhD (Committee Member) Subjects: Mechanical Engineering