Materials Science and Engineering Commons^™

Ellipticity-Controlled Exceptional Points From Nanoscale Metasurfaces, Benjamin Goldberg

McKelvey School of Engineering Graduate Student Theses & Dissertations

Precise control over light polarization is critical for advancing technologies in telecommunica- tions, quantum computing, and image sensing. However, existing methods for manipulating polarization around exceptional points in non-Hermitian systems, have exclusively focused on circular polarization and work with reflected light. To address this limitation, we de- velop a novel metasurface platform with high-Q resonators that enables tunable control of polarization exceptional points across arbitrary ellipticity for transmitted light. Our design uses orthogonally polarized guided mode resonators in a two-layer silicon metasurface, where careful tuning of the dipolar guided mode resonances (DGMRs) and layer spacing allows us to control the …

Ohmic Contacts For Fabrication Of Sic Cmos Devices, Anthony Di Mauro

Graduate Theses and Dissertations

Today’s world of electronics is dominated by semiconductor devices which utilize silicon as their substrate material. Though, silicon is not ideal for semiconductor devices in high-voltage or high-temperature applications. Additionally, the efficiency of silicon devices becomes drastically reduced in nonideal operating conditions. Therefore, finding alternatives to silicon?based devices has been a topic for decades now. A few great candidates to replace silicon devices for said applications include Silicon Carbide (SiC), Gallium Nitride (GaN), and Aluminum Arsenide (AlAs). SiC has grown its reputation as the best candidate, when compared to other potential alternatives, due to its wide bandgap, high operating frequency, …

Thermal Conductivity Characterization Of High Oleic Vegetable Oils Based Hybrid Nanofluids Formulated Using Gnp, Tio2, Mos2, Al2o3 Nanoparticles For Mql Machining, Anthony Chukwujekwu Okafor, Tobechukwu Kingsley Abor, Saidanvar Esanjonovich Valiev, Ignatius Echezona Ekengwu, Abiodun Saka, Monday Uchenna Okoronkwo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents the results of thermal conductivity characterization of six high oleic soybean oil (HOSO) and four high oleic canola oil (HOCO)-based hybrid nanofluids formulated with four types of nanoparticles (Graphene nanoplatelet (xGnP), TiO2, MoS2, and Al2O3) at nanoparticles wt.% concentration from 1 % to 7 % in 1 % increment using the two-step method for use in MQL machining of difficult-to-cut metals. Thermal conductivity of the formulated hybrid nanofluids were measured using Thermtest Transient Hot Wire Liquid Thermal Conductivity Meter at temperatures from 25 °C to 75 °C in increment of 10 °C. Obtained results showed that thermal …

Pressureless Sintering Of Sic - Oxide Multiphase Ceramics For Protective Coating Applications, Reilly Boros

All Theses

For hydrogen-fueled combustion, there exists a demand to improve coating materials that are capable of protecting SiC_f/SiC CMC turbine material. Promising coating materials must be able to shield from harsh oxidation while working at extremely high temperatures. The work presented in this thesis aims to expand the understanding of two promising material systems for integrated environmental barrier coating (EBC) – thermal barrier coatings (TBC) by fabricating bulk composite ceramic samples and performing characterization to further understand their sintering behaviors. In this study, a processing procedure to consistently produce dense composite ceramics of PDC SiC – Y₂Si …

Removal Capabilities Of Zeolite And Zero Valent Iron With High-Level Waste Tank Radionuclides And Metals: Cesium, Strontium And Chromium, Colette R. Towles

UNLV Theses, Dissertations, Professional Papers, and Capstones

High level nuclear waste (HLW) has been disposed for temporary storage in underground steel tanks at the Department of Energy Nuclear sites. For example, at the Hanford Site, WA, and Savannah River Site (SRS), SC, HLW account for eighty-eight million gallons (Mgal) and 450 million Curies (MCi) of radioactivity. In the early nuclear activity at Hanford, the waste was discharged to single-shell steel tanks, and the lack of secondary containment allowed leaks, contaminating soil and groundwater. Despite tremendous efforts to stabilize the liquid waste at nuclear sites, treatment is complex, costly, and time-consuming; therefore, HLW may have to be stored …

Experimental Evaluation Of A Recrosslinkable Co2-Resistant Micro-Sized Preformed Particle Gel For Co2 Sweep Efficiency Improvement In Reservoirs With Super-K Channels, Adel Alotibi, Tao Song, Ali Al Brahim, Baojun Bai, Thomas P. Schuman

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

A recross linkable CO₂-resistant branched preformed particle gel (CO₂-BRPPG) was developed for controlling CO₂ injection conformance, particularly in reservoirs with super-permeable channels. Previous work focused on a millimeter-sized CO₂-BRPPG in open fractures, but its performance in high-permeability channels with pore throat networks remained unexplored. This study used a sand pack model to evaluate a micro-sized CO₂-BRPPG under varying conditions of salinity, gel concentration, and pH. at ambient conditions, the equilibrium swelling ratio (ESR) of the gel reached 76 times its original size. This ratio decreased with increasing salinity but remained stable …

Cyclic Thermal Stability Of Native Oxide Solar Thermal Absorbers On Femnnialcr High Entropy Alloys For Energy Applications, Xiaoxue Gao

Dartmouth College Ph.D Dissertations

High entropy alloys (HEAs) are promising candidates for cost-effective high-temperature materials in high-efficiency power cycles. A potential application is in concentrated solar power (CSP) systems, where native oxides of cost-effective FeMnNiAlCr HEAs can also synergistically serve as a high-efficiency solar thermal absorber. However, the huge and repetitive temperature change of the CSP system in day-night cycles greatly challenges its thermal stability. In this thesis, we investigated the cyclic oxidation behavior of FeMnNiAlCr HEAs to improve the optical performance and thermal stability of their native oxides as a solar absorber for next-generation CSP systems. We found that the duplex oxide scale …

Investigating Functionalized Cvd Graphene Heterostructures As Platforms For Hydrogen Gas Sensing, Evans Asiedu Addo-Mensah

Graduate Theses and Dissertations

The hydrogen economy is rapidly advancing and is poised to become one of the world's largest economies, driven by the abundance of hydrogen gas. Several organizations, particularly in the United States of America, are closely or have been monitoring this development, with rapidly increasing interest. Considering that hydrogen gas has no taste, smell (odor), or color, and very combustible, it’s imperative to develop detectors and sensors capable of rapidly detecting leaks to prevent application disasters. Owing to its extraordinary mechanical and electrical characteristics, graphene is the material that has been studied the most. When combined with hexagonal boron nitride (hBN), …

Influence Of Glycopolymer Structure On Amphiphilic, Hybrid, Linear Branched Block Copolymer Properties For Use In Biomedical Applications, Kevin Green

Dissertations

The focus of this dissertation is evaluating and adding fundamental knowledge regarding the structure-property relations of glycopolymers used in the design of hybrid block copolymers (HBC) that are cable of self-assembling into delivery vehicles for biomedical applications. A shift to the utilization of natural materials in the design and fabrication of drug-delivery vehicles has garnered significant attention. Understanding the effects of linear glycopolymers content and composition on the resulting HBCs properties can provide valuable insight into how these materials may be tailored for use in targeted biological applications.

The first chapter introduces current literature on the need for improvement in …

Neural Operator And Physics-Informed Deep Learning Approaches For Inverse Design Of Composites And Manufacturing Processes, Minglei Lu

All Dissertations

In this dissertation, artificial intelligence (AI) models are designed and used to accelerate inverse design of composites and manufacturing processes. The critical bottlenecks in machine learning (ML) including data availability, data quality, model generalization and adaptation, interpretability, physical consistency, and the ’black box’ nature of models for the inverse design are addressed. And the proposed AI models are tested under different engineering scenarios. Firstly, a fast deep neural operator (DNO) structure was developed to significantly reduce training time. This model was tested in the context of additive manufacturing, a transformative industrial technology that allows for the creation of materials with …

Investigation Of Conductive Die-Top Thermal Capacitors During Short Circuit Operation Of Silicon Carbide Devices, Youssef Abotaleb

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Silicon carbide (SiC) power devices have garnered significant attention in recent years due to their superior thermal and electrical properties compared to traditional silicon devices. However, SiC power devices suffer from severe reliability issues arising from their mechanical properties. This is because the Young's modulus of SiC is about three times larger than that of silicon, which correspondingly raises the mechanical stresses acting on the bonding structure, often leading to device failure under power shock events.

Traditional packaging materials and designs tend to constrain SiC performance, as hot-spot temperature resulting from a power shock is one of the key factors …

Understanding Defect Dynamics In Black Phosphorene Under Noble Gas Ion Irradiation., Saransh Gupta

Electronic Theses and Dissertations

Controlled introduction of defects in phosphorene using high-energy ion beams offers a promising route to design novel high-performance materials for energy technologies. However, this potential remains underexplored due to a lack of fundamental understanding of the atomic-scale mechanisms governing the production, accumulation, and temporal evolution of defects during ion irradiation. Here, we employ a combination of classical and ab initio molecular dynamics simulations to elucidate the effects of ion energy, angle of incidence, noble gas ion size/mass, and fluence on (a) defect generation (i.e., point defects, topological imperfections, voids), (b) atomic-scale mechanisms of defect formation and re-arrangement, and (c) defect …

Thermal Conductivity Characterization Of High Oleic Vegetable Oils Based Hybrid Nanofluids Formulated Using Gnp, Tio2, Mos2, Al2o3 Nanoparticles For Mql Machining, Anthony Chukwujekwu Okafor, Tobechukwu Kingsley Abor, Saidanvar Esanjonovich Valiev, Ignatius Echezona Ekengwu, Abiodun Saka, Monday Uchenna Okoronkwo

Chemical and Biochemical Engineering Faculty Research & Creative Works

This paper presents the results of thermal conductivity characterization of six high oleic soybean oil (HOSO) and four high oleic canola oil (HOCO)-Based hybrid nanofluids formulated with four types of nanoparticles (Graphene nanoplatelet (xGnP), TiO₂, MoS₂, and Al₂O₃) at nanoparticles wt.% concentration from 1 % to 7 % in 1 % increment using the two-step method for use in MQL machining of difficult-to-cut metals. Thermal conductivity of the formulated hybrid nanofluids were measured using Thermtest Transient Hot Wire Liquid Thermal Conductivity Meter at temperatures from 25 °C to 75 °C in increment …

A General Model For The Ductility Of Intermetallics Applied To Fe-Co Alloys, Wesley Everhart, Joseph Newkirk

Materials Science and Engineering Faculty Research & Creative Works

The mechanical properties, specifically ductility, of high performing soft magnets such as Fe-Co alloys are a limiting factor to their broader use in a number of systems. The understanding of the mechanical robustness in these materials is currently insufficient to be able to support the growing interest in applications such as magnetic shielding or electric motors. Fe-Co alloys provide the highest commercially available magnetic saturation and high magnetic permeability but have very poor ductility. The addition of vanadium to these alloys has allowed for significant commercialization and some ductility improvements, but the fundamental reasons for the observed improvements are not …

Fabrication And Performance Of Scalable Bio-Engineered Porous Layers For Efficient Co2 Capture, Mary Sharon Rose Bondugula

Theses and Dissertations

This dissertation addresses the critical challenge of mitigating climate change by advancing CO2 capture technologies. As global CO2 emissions continue to rise, effective methods for capturing and separating CO2 from industrial processes are essential to combat climate change. Existing CO2 capture systems, such as Pressure Swing Adsorption (PSA) and Temperature Swing Adsorption (TSA), often rely on packed bed designs that face limitations, including poor heat and mass transfer, slow gas diffusion, and low thermal conductivity, reducing their efficiency. To overcome these challenges, this dissertation explores innovative solutions by developing advanced adsorbent coatings and scalable bed configurations.

This research begins by …

Prediction Of Dislocation Density During Casting Of 316 Stainless Steel Based Alloys As A Function Of Chromium And Nickel Composition, Abhishek Chitradurga Ranganath

All Theses

By the 1990s, computational methods were beginning to be used to study dislocation density in mental casting. Prior to that time research was based heavily on laboratory studies. This move was encouraged by the need to overcome limitations that experimental approaches had, including high costs and time-consuming processes, and needs of researchers to understand atomic-scale phenomena. Computational techniques allow complex materials to be simulated in cost effective way and can provide insight into behaviour that could never be determined through experimental methods alone.

This work utilized molecular dynamics (MD) simulations along with machine learning approaches to examine the dislocation density …

Multi-Scale Modeling Of Dna-Templated Aggregates For Excitonic Applications, German Barcenas Moncada

Boise State University Theses and Dissertations

Quantum entanglement occupies a central role in the application of quantum mechanics towards emerging technologies of quantum information systems. Meanwhile, quantum entanglement is believed to be observed at room temperature in photosynthetic complexes in plants and algae through the energy transfer of dye molecules. The goal of this project is to engineer dye properties and their arrangement when dyes and aggregates are covalently attached to DNA so that the emergent property of exciton delocalization is as coherent, predictable, detectable and controllable. The creation of such a platform would enable the continued study of near room-temperature quantum entanglement and the more …

Synthesis And Doping Effects In Highly Conductive Chalcogenide Solid Electrolytes., Selim Halacoglu

Electronic Theses and Dissertations

Lithium and sodium ion batteries have been a vital component in the growth of small, portable electronic devices and EVs over the past 30 years. For future energy needs, changes to battery chemistry and composition will be necessary for two primary reasons: safer and higher energy batteries. Metal anodes have not seen widespread commercialization because of their propensity to react aggressively with the flammable liquid electrolytes commonly used in modern batteries. Non-flammable solid-state batteries (SSB) with solid electrolytes can safely be used with metal anodes, potentially providing a solution to both problems. The future perspective of safer battery is that …

High Energy Density Lithium-Ion Battery Materials., Rachel Dewees

Electronic Theses and Dissertations

Growth of the EV industry has created an increased demand for Li-ion battery electrode materials, and support of a robust lithium-ion battery supply chain is a national imperative. For mainstream acceptance in the American market, the range of EVs must be improved, i.e., the energy density of the battery must be increased. Increasing the specific capacity of the electrode materials is the most direct strategy for increasing the energy density of the battery. Silicon anode materials have a theoretical capacity of over 3700 mAh·g^-1 - an order of magnitude beyond that of the graphitic materials which are currently implemented. …

Stability Of Nuclear Thermocouples, Scott Riley

Boise State University Theses and Dissertations

The mission of the Department of Energy, Office of Nuclear Energy (DOE-NE) is to advance nuclear power as a resource capable of meeting the nation’s energy, environmental and national security needs by resolving technical, cost, safety, proliferation resistance, and security barriers through research and development. In the pursuit of safer and more economic energy production from existing nuclear reactors and future generation IV reactors, new cladding, fuel, and structural materials are being developed. However, data on the performance of these materials in accident scenarios and relevant generation IV reactor conditions is limited. Currently, thermocouples are the most commonly used temperature …

Advancing Biofabrication Methodologies To Develop Biomimetic Tissue Scaffolds For Musculoskeletal Applications, Nashaita Yezdi Patrawalla

Theses and Dissertations

Musculoskeletal injuries impose a significant global burden, affecting millions and generating an economic toll exceeding $14 billion. Tissue engineering has gained traction as a promising strategy offering potential for functional restoration of damaged musculoskeletal tissues. This research aims to advance biofabrication techniques for generation of biomimetic tissue scaffolds, by optimizing scaffold design and modulating fabrication process parameters to generate scaffolds for musculoskeletal regeneration with application-specific tailored properties. In this realm, collagen-based biomaterials have been extensively investigated for tendon and ligamentous applications, and in combination with bioceramics incorporated into the collagen framework to produce composite scaffolds that better recapitulate the native …

Density-Driven Investigations Of Ruthenium Binary Compounds Rux2 (X = O, S, N), Melanie White

UNLV Theses, Dissertations, Professional Papers, and Capstones

Exploration and fine-tuning of the energy landscape of materials can be accessed by means of changes in material density, a key principle of high pressure research. Density-driven changes impact variations in oxidation states and coordination numbers for the element constituents of a compound. Pressure-induced modification of intrinsic density can promote the formation of new materials, variations in physical properties, and transformations in crystallographic symmetry. With this as our foundation, we focus on ruthenium binary compounds - altering the anion species to change electronegativity while probing pressure and temperature effects. This led us to the present study of ruthenium oxide RuO2, …

Development Of Uranium Fluoride Microstructures, Harry Jang

UNLV Theses, Dissertations, Professional Papers, and Capstones

Uranium microstructured materials with controlled size and shape have found applications in several branches of the nuclear industry including as targets for medical isotopes production, fuels for nuclear reactors, standards for analytical measurements, and energy sources for space exploration. Morphological studies of actinide materials are also highly relevant to nuclear forensics-related work. Other potential applications include information storage, catalysis, sensors, and luminescent devices. Most studies on uranium microstructured materials have focused on binary oxides, nitrides, carbides, and fluorides, with the spherical shape being the dominant morphology. Prior to the work reported in this dissertation, aside from UF4 microspheres (ms) and …

Magnetic Nano And Micro Rods As Tools For Characterizing Materials Mechanical Properties: Fundamentals And Applications, Artis Brasovs

All Dissertations

The focus of this dissertation is insect blood (Hemolymph). Hemolymph is analyzed by taking a materials science approach. Rheological characterization of hemolymph has been performed for the first time. Owing to a minute amount of available material, a new protocol was established where Magnetic Rotational Spectroscopy (MRS) with ferromagnetic nanorods was employed. The challenge was examining the microliter droplets' viscosity in less than a few minutes. This challenge was successfully resolved.

Blood is critical for the insect's survival: after wounding, the insect has to seal the wound quickly, in a few minutes. As the mechanism of fast clotting has never …

Laser Processing Of Multi-Phase Ceramics, Siddhartha Sarkar

All Dissertations

This research explores laser-based processing for multi-phase ceramics, offering a faster, more energy-efficient alternative to conventional ceramic fabrication. Four material systems are explored: silica-titania, alumina-iron, polymer-derived ceramic SiC-gadolinium zirconate, and polymer-derived ceramic SiC-yttrium silicate.

The silica-titania study presents a novel direct CO₂ laser writing approach to fabricating pure silica and silica-titania glasses with exceptional dimensional control and optical transparency, enabling fine spatial resolution, instantaneous consolidation, and eliminating post-heat treatment. Notably, the TiO₂ solubility in the silica network achieved is higher than previously reported, with structures remaining crack-free and transparent up to a specific TiO₂ percentage.

The alumina-iron …

Nanostructured Silicon Meta-Waveguides And Surfaces For Enhanced Light-Matter Interaction, Saddam Gafsi

All Dissertations

In this study, we tackle the challenge of light-matter interaction engineering and local field enhancement using various silicon photonic platforms based on three different approaches. (i) The first approach is based on boundary condition engineering where we present and show through simulation and experimental results, a silicon nanodisk “diabolo” configuration able to support significant local field enhancement levels in the range ~102 to 104 in the high index medium through proper structural modifications at the nanoscale. We show that the presented optical behavior is consistent with the anapole modes characterized by the observed near-field enhancement and coinciding with far-field suppression. …

Enhancing Protonic Ceramic Fuel Cells By Advanced Laser Processing For Superior Performance, Tianyi Zhou

All Dissertations

As global temperatures rise, the demand for clean energy solutions intensifies. Protonic ceramic fuel cells (PCFCs) offer advantages like higher conductivity at moderate temperatures (300–700 °C), fuel flexibility, stability, and lower costs. However, traditional PCFC manufacturing faces challenges with interface defects, structural imperfections, and scalability, especially in producing large-area cells and stacks.

This work addresses these issues using advanced laser processing techniques. Laser ablation and direct laser rapid additive manufacturing (DL-RAM) enable precise control of PCFC microstructures, removing surface defects and increasing bonding strength for higher efficiency. Digital layer deposition allows for large-area PCFC single cells and stack production with …

Exploring The Compositional Limits Of Y2o3-Al2o3-Sio2 Optical Fibers, Miranda Stone

All Dissertations

Of the widely varying compositions fabricated into optical fibers using the molten core method (MCM), the most studied by far as been those in the Y₂O₃-Al₂O₃-SiO₂ (YAS) system. Such fibers have been shown to be of interest for fiber amplifiers and lasers since they exhibit a good balance between reasonable loss, intrinsically low optical nonlinearities, and efficient gain. The majority of the fibers studied globally to-date have primarily focused on YAG-derived fibers, i.e., YAG (Y₃Al₅O₁₂) single crystals drawn in a pure SiO₂ cladding glass) …

Improving Thermionic Power Generation Via The Reduction Of Emission Barriers, Chace E. Franey

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

This thesis investigates methods to improve the performance of thermionic energy converters (TECs) by reducing the emission barriers. A TEC generates electricity from thermal energy when electrons are emitted from a hot electrode (the emitter) through a vacuum gap and absorbed by a cooler electrode (the collector). Due to their lack of working fluids and inherently compact nature, TECs have garnered attention over the years for their potential as a means of power generation in space or high-grade waste heat recovery. Historically, however, the practical implementation of TECs has been hindered by significant technical challenges. Recent advancements in microfabrication techniques …

Electrochemical Treatment Of Mining And Oilfield Wastewater Using Recycled Titanium Alloy Electrodes, Sean Michael Thompsen

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

This thesis explores the integration of circular economy principles into wastewater treatment through the innovative use of recycled Ti-6Al-4V titanium alloy electrodes. By repurposing titanium alloys from metal additive manufacturing (AM) waste, the research aims to address the treatment of acidic and oil-contaminated industrial wastewater in a sustainable manner. The recycled electrodes demonstrate notable stability and fouling resistance in challenging acidic conditions, attributed to their unique surface porosity and conductive properties. Electrochemical processes, including hydrogen evolution at the cathode, facilitate metal ion precipitation and destabilize surfactant-stabilized oil droplets. Cyclic voltammetry and long-term stability tests highlight the electrodes’ resilience, providing an …