Materials Science and Engineering Commons^™

The Effect Of Plasma On Graphene Quality In An Inductively Couple Plasma Chemical Vapor Deposition Reactor, Brendan Coyne

Maseeh Summer Undergraduate Research Experience

Despite continued interest in research and application development, full scale graphene production is still limited by many factors including prohibitively high growth temperature requirements. Extremely high quality graphene growth is possible at high temperatures using chemical vapor deposition (CVD). Use of an inductively coupled plasma chemical vapor deposition (ICP CVD) reactor with the benefit of precursor gas decomposition through plasma generation, may provide possibility to reduce growth temperature. Herein, we report plasma’s effects on graphene growth by comparing growths of increasing power supplied to plasma generation and changes in precursor gas ratios. Plasma composition was characterized by ultraviolet and visible …

Conditional Averaging And Classification In The Near Wake Of A Wind Turbine Array Boundary Layer, Sarah E. Smith

Maseeh Summer Undergraduate Research Experience

Flow perturbation induced by interaction with a turbine rotor produces considerable turbulence which can alter the productivity of subsequent units within a wind farm. Previous methods have characterized near wake vorticity of a single turbine as well as recovery distance for various turbine array configurations. This study aims to build from previous methods of analysis from the perspective of the rotor well within a turbine array and develop a model to examine points of significant imposition in relation to rotational effects. Hot wire anemometry was employed downstream of a turbine located in the middle of the third row in a …

Deposition Velocity Dependence On Urban Morphology, Rawand Muzafar Rasheed

Maseeh Summer Undergraduate Research Experience

Understanding the interactions between the atmospheric boundary layer and urban structures provides insights into emerging problems such as green building design as well as dispersion and deposition of pollutants on urban structures. Characterization of deposition velocity dependence through the naphthalene sublimation method on model urban structures is conducted herein where the analogous fundamental transport mechanisms of momentum and mass transport is obtained via mass of naphthalene transferred. Via wind tunnel experiments, results show that deposition velocity of naphthalene from urban structures increases with increased number of urban structures ahead of the point of investigation. This is attributed to the wakes …

Peridynamic Models For Fatigue And Fracture In Isotropic And In Polycrystalline Materials, Guanfeng Zhang

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

To improve design and reliability, extensive efforts has been devoted to understanding damage and failure of materials and structures using numerical simulation, as a complement of theory and experiment. In this thesis, peridynamics is adopted to study fatigue and dynamic failure problems.

Fatigue is a major failure mode in engineering structures. Predicting fracture/failure under cyclic loading is a challenging problem. Classical model cannot directly be applied to problems with discontinuities. A peridynamic model is adopted in this work because of important advantages of peridynamics in allowing autonomous crack initiation and propagation. A recently proposed peridynamic fatigue crack model is considered …

Data Driven Discovery Of Materials Properties., Fadoua Khmaissia

Electronic Theses and Dissertations

The high pace of nowadays industrial evolution is creating an urgent need to design new cost efficient materials that can satisfy both current and future demands. However, with the increase of structural and functional complexity of materials, the ability to rationally design new materials with a precise set of properties has become increasingly challenging. This basic observation has triggered the idea of applying machine learning techniques in the field, which was further encouraged by the launch of the Materials Genome Initiative (MGI) by the US government since 2011. In this work, we present a novel approach to apply machine learning …

Infrared Energy Conversion In Plasmonic Fields At Two-Dimensional Semiconductors, Gregory Thomas Forcherio

Graduate Theses and Dissertations

Conversion of infrared energy within plasmonic fields at two-dimensional, semiconductive transition metal dichalcogenides (TMD) through plasmonic hot electron transport and nonlinear frequency mixing has important implications in next-generation optoelectronics. Drude-Lorentz theory and approximate discrete dipole (DDA) solutions to Maxwell’s equations guided metal nanoantenna design towards strong infrared localized surface plasmon resonance (LSPR). Excitation and damping dynamics of LSPR in heterostructures of noble metal nanoantennas and molybdenum- or tungsten-disulfide (MoS2; WS2) monolayers were examined by parallel synthesis of (i) DDA electrodynamic simulations and (ii) near-field electron energy loss (EELS) and far-field optical transmission UV-vis spectroscopic measurements. Susceptibility to second-order nonlinear frequency …

Plasmon-Mediated Energy Conversion In Metal Nanoparticle-Doped Hybrid Nanomaterials, Jeremy Dunklin

Graduate Theses and Dissertations

Climate change and population growth demand long-term solutions for clean water and energy. Plasmon-active nanomaterials offer a promising route towards improved energetics for efficient chemical separation and light harvesting schemes. Two material platforms featuring highly absorptive plasmonic gold nanoparticles (AuNPs) are advanced herein to maximize photon conversion into thermal or electronic energy. Optical extinction, attributable to diffraction-induced internal reflection, was enhanced up to 1.5-fold in three-dimensional polymer films containing AuNPs at interparticle separations approaching the resonant wavelength. Comprehensive methods developed to characterize heat dissipation following plasmonic absorption was extended beyond conventional optical and heat transfer descriptions, where good agreement was …

Investigation Of Fes2 Nanoparticles For Use In Optoelectronic And Thermoelectric Applications, Rick Tefal Eyi Nkoghe

Graduate Theses and Dissertations

Iron pyrite (FeS2) is the most abundant sulfide material on earth. This material has been widely investigated by researchers because of its optical properties. However, it has been difficult to produce High efficiency FeS2 based solar cells. This is due to many different impurities that arise when making the materials. The ability to synthesize pure pyrite FeS2 material is therefore critical for applications.

Pure Iron pyrite nanocrystals were synthesized using hot injection by mixing sulfur with an iron precursor in the presence of an amine. To improve the stability, shorter ligands replaced the native amines ligands. The stability of the …

Multifunctional Transition Metal Oxide Core Shell Magnetic Nanoparticles, Mahmud Reaz

Graduate Theses/Dissertations

Oxide core-shell nanoparticles (CSNPs) have attracted considerable interest for their multifunctional properties. Luminescent ZnO, ferroelectric BaTiO3, and inverse spinel iron oxide can be exploited to develop magneto-luminescent and multiferroic nanomaterials. The novel sonochemical method has been used to synthesize the nanomaterials. Atomic-scale spectroscopy establishes the core-shell nature and multifunctional properties of the nanomaterials. Magnetic hysteresis (coercivity, remnant, and saturation magnetization) and temperature dependent data indicate the key structural difference between the oxidized and reduced ZnO/iron oxide CSNPs. Variation in the coercive field and remnant and saturation magnetization further confirms the presence of different iron oxides in the shell region. Temperature …

Application Of Raman Spectroscopy To Study Of Biological Systems, Neva Agarwala

Graduate Theses/Dissertations

Raman spectroscopy is an important tool of molecular characterization based on inelastic scattering of monochromatic light by molecules. Since Raman spectra reflect unique vibrational properties of materials, the method offers a potential of selective molecular identification. Furthermore, surface-enhanced Raman spectroscopy (SERS) also is capable of a high sensitivity, since inelastic scattering of light from the molecules is strongly enhanced when Raman-active molecules are located close to roughened noble metal surfaces. In this thesis, Raman characterization protocols of liquid biological samples are optimized. Raman spectra of two different cell cultures, yeast cells and HeLa cells, were collected and interpreted. The potentiality …

Ftir Spectroscopy Of Hot Exoplanets: A First Step In Experimental Procedure And Analysis, Heath Emmanuel Gemar

Graduate Theses/Dissertations

In this thesis, I demonstrate how I constructed a complete experimental package to view FTIR Spectroscopy of constituents that make up hot, rocky exoplanets. I examine in detail the engineering and construction of such a system. Also, I developed a full computational package to analyze spectra in association and relate the analysis to that of real world application. The new system produces reproducible IR spectra on exoplanet analogs and can be used to probe complex chemistry composition at high temperatures.

Analysis Of Tool Wear And Tool Life Of Cutting Tool Inserts Using Statistical Process Control Charts: A Case Study, Evan R. Ferrell

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Business and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Evan R. Ferrell on April 28, 2017.

Recent Progress In Template-Assisted Synthesis Of Nitrogen-Doped Porous Carbons For Oxygen Electroreduction, Wenhan Niu, Ligui Li, Shaowei Chen

Journal of Electrochemistry

Nitrogen (N)-doped porous carbons are potential alternatives to precious metal catalysts for oxygen reduction reaction (ORR) at the cathodes of proton exchange membrane fuel cells and metal-air batteries. Template-assisted synthesis has been used extensively as a robust and versatile method in the preparation of such carbon catalysts, where the ORR activity has been found to be dependent on various structural parameters, such as the concentrations and molecular configurations of the dopants, and the porosity, surface accessibility and electrical conductivity of the carbon materials. In this review, we summarize recent progress in this area of research focusing on the design, preparation …

Impact Of Nafion Loading And Anion Adsorption On The Synthesis Of Pt Monolayer Core-Shell Catalysts, Lijun Yang, Dustin Banham, Elod Gyenge, Siyu Ye

Journal of Electrochemistry

Carbon supported palladium (Pd) nanoparticles were used as a model core material for the synthesis of platinum (Pt) monolayer core-shell catalysts using rotating disk electrode method and a copper (Cu) under potential deposition technique. The impact of Nafion on the synthesis process was revealed by electrochemical testing with various Nafion contents. The existence of Nafion influenced the Cu under potential deposition, galvanic replacement and eventually the oxygen reduction reaction activity of the core-shell catalyst. However, as long as the Nafion content was less than 5 wt% in the test film, adding Nafion could help to bind catalyst onto the surface …

Designing Pt-Skin Of Pt-Based Bimetallic Electrocatalysts For Oxygen Reduction Reaction, Binwei Zhang, Yunxiao Wang, Yanfei Xu, Huakun Liu, Shixue Dou

Journal of Electrochemistry

In the past decade, great advancement has been made in the development of nanocatalysts for energy conversion and storage. Pt-skin of Pt-based bimetallic has shown a great potential in the tuning the electronic structures of electrocatalytically active materials toward oxygen reduction reaction. Here, we offer a brief overview of the recent research on the design and preparation of catalysts. Our focus is paid on the systematic studies of preparation and performance of Pt-skin catalysts towards oxygen reduction reaction.

Comparative Studies Of Fe, Ni, Co And Their Bimetallic Nanoparticles For Electrochemical Water Oxidation, Maduraiveeran Govindhan, Brennan Mao, Aicheng Chen

Journal of Electrochemistry

The design of efficient, durable, and earth-abundant electrocatalysts via environmentally compatible strategies for the oxygen evolution reaction (OER) is a vital for energy conversion processes. Herein we report a facile approach for the fabrication of low-cost and earth abundant metal catalysts, including iron (Fe), nickel (Ni), cobalt (Co), CoNi, and CoFe nanoparticles (NPs) on titanium (Ti) substrates through a one-step electrochemical deposition. Field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) spectrocopy, X-ray photoelectron spectroscopy (XPS), and electrochemical techniques were employed to characterize these nanoparticles. Our electrochemical results revealed that among the five synthesized nanomaterials, the …

Comparison Of Oxygen Reduction Reaction Activity Of Pt-Alloy Nanocubes, Yongan Tang, Lin Dai, Shouzhong Zou

Journal of Electrochemistry

Alloying Pt with the first row non-noble transition metals has been demonstrated to increase the catalytic activity toward oxygen reduction reaction (ORR), which is the cathode reaction of the proton exchange membrane fuel cells (PEMFCs) and metal-air batteries. However, how much the ORR activity improvement comes from the alloying elements remains controversial. In this paper, the nanocubes of PtMn, PtFe, PtCo, and PtNi with the similar size and composition were prepared and their ORR activities were explored, in order to investigate the effects of alloying elements on the catalytic activity. The use of cubic shape particles minimizes the contribution to …

Novel Composites Between Nano-Structured Nickel Sulfides And Three-Dimensional Graphene For High Performance Supercapacitors, Xiaomin Wang, Huanglin Dou, Zhen Tian, Jiujun Zhang

Journal of Electrochemistry

In this paper, a three-dimensional graphene (3DG) network grown on nickel foam was employed as a template for synthesizing graphene-based composite materials of supercapacitor electrode. The composites (crystal Ni₃S₂ nanorods on the surface of 3DG (abbreviated as Ni₃S₂/3DG)) were obtained through a one-step hydrothermal reaction. The morphological and structural evolution of the Ni₃S₂/3DG composites were investigated by SEM, TEM, XRD and Raman spectroscopy. Detailed electrochemical characterization showed that the Ni₃S₂/3DG-coated electrodes exhibited both a specific capacitance as high as 1825 F·g^-1 at 5 mV·s …

Electrodeposition Of Ruo2 Layers On Tio2 Nanotube Array Toward Co2 Electroreduction, Bei Jiang, Lina Zhang, Xianxian Qin, Wenbin Cai

Journal of Electrochemistry

RuO₂/TiO₂ composite materials have multitude of electrocatalytic applications including but not limited to CO₂ reduction reaction (CO₂RR). RuO₂/TiO₂ electrodes were previously prepared by repetitive coating and thermal decomposition (TD) of a Ru(III) precursor solution on Ti substrate. In this work, electrochemical potential cycling is applied to deposit amorphous RuO₂ (α-RuO₂) layers onto TiO₂ nanotube array (TNA) (RuO₂^CV/TNA) preformed on Ti foil. SEM, GIXRD, and voltammetry are applied to characterize the structures of the resulting RuO₂^CV/TNA. Ru loading on the RuO_{2 …}

Effects Of Yttria Concentration And Microstructure On Electric Breakdown Of Yttria Stabilized Zirconia, Oratai Jongprateep, Vladimir Petrovsky, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Ceramic materials have great potentials for capacitor application. However, low breakdown strength of the materials remains a key challenge for development of high-performance capacitors. In this study, yttria stabilized zirconia (YSZ) were fabricated and tested for breakdown strength. YSZ samples with 3, 8, and 10 mol% yttria were carefully processed to control grain size and porosity level. Experimental results revealed that breakdown strength as high as 2 MV/cm could be achieved. The breakdown strength was not significantly affected by porosity level, but it was by yttria concentration. Relationship among yttria concentration, residual porosity and breakdown strength is discussed in this …

Fabrication And Study Of The Structure And Magnetism Of Rare-Earth Free Nanoclusters, Bhaskar Das

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

No abstract provided.

Antiferromagnetism In The Van Der Waals Layered Spin-Lozenge Semiconductor Crte3, Michael Mcguire, V. Ovidiu Garlea, Santosh Kc, Valentino Cooper, Jiaqiang Yan, Huibo Cao, Brian Sales

Faculty Publications

The crystallographic, magnetic, and transport properties of the van der Waals bonded, layered compound CrTe3 have been investigated on single-crystal and polycrystalline materials. The crystal structure contains layers made up of lozenge-shaped Cr4 tetramers. Electrical resistivity measurements show the crystals to be semiconducting, with a temperature dependence consistent with a band gap of 0.3 eV. The magnetic susceptibility exhibits a broad maximum near 300 K characteristic of low dimensional magnetic systems. Weak anomalies are observed in the susceptibility and heat capacity near 55 K, and single-crystal neutron diffraction reveals the onset of long-range antiferromagnetic order at this temperature. Strongly dispersive …

Interference Of Light In Multilayer Metasurfaces: Perfect Absorber And Antireflection Coating, Khagendra Prasad Bhattarai

USF Tampa Graduate Theses and Dissertations

We have studied several metamaterials structures with multiple layers by explaining them theoretically and verifying experimentally. The engineered structures we have designed work either as a perfect absorber or antireflection coating. The multilayer model as we call it Three Layer Model (TLM) has been developed, which gives the total reflection and transmission as a function of reflection and transmission of individual layers. By manipulating the amplitude and phase of the reflection and the transmission of the individual layers, we can get the required functionality of the optoelectronic devices. To get zero reflection in the both perfect absorber and the antireflection …

Effect Of Plasma Dynamics On Gallium Nitride Nanorod And Growth By Molecular Beam Epitaxy, Dever Paul Norman

Theses and Dissertations

GaN is a wide bandgap semiconductor known for its use in high-frequency switching electronics and laser diodes, its stability as a high-temperature transistor material, and a radiation resistance which makes it an ideal material for space applications. Additionally, the discovery of the bandgap tunability of nitride materials using GaN has led to successful development of adjustable wavelength LED devices. However, the success of devices far outpaces the understanding of their material growth, making advances difficult to build upon. Plasma- Assisted Molecular Beam Epitaxy (PA-MBE) is an ideal growth method for achieving very precise structures for detailed study. Although plasma itself …

Wall Panel Optimization For Refugee Shelters In Germany: An Ahp Study, Zhu Jiadong

Masters Theses & Specialist Projects

The German government is experiencing difficulties housing and assimilating Syrian refugees in its borders. Erecting temporary shelters on location is one way to deal with the current crises. This thesis attempts to use Analytic Hierarchy Process (AHP) to determine the optimum combination of materials and construction methods to be used in the shelter’s walls in order to improve the living conditions of the refugees and to ensure that the cost is acceptable to the German government. This thesis compares six existing wall panel products from China, which have the lowest cost on the worldwide market. The R-value, strength, price, weight, …

Tracking Characteristics Of Tracer Particles For Piv Measurements In Supersonic Flows, Fang Chen, Hong Liu, Zifeng Yang, Hui Hu

Mechanical and Materials Engineering Faculty Publications

The tracking characteristics of tracer particles for particle image velocimetry (PIV) measurements in supersonic flows were investigated. The experimental tests were conducted at Mach number 4 in Multi-Mach Wind Tunnel (MMWT) of Shanghai Jiao Tong University. The motion of tracer particles carried by the supersonic flow across shockwaves was theoretically modelled, and then their aerodynamic characteristics with compressibility and rarefaction effects were evaluated. According to the proposed selection criterion of tracer particles, the PIV measured results clearly identified that the shockwave amplitude is in good agreement with theory and Schlieren visualizations. For the tracer particles in nanoscales, their effective aerodynamic …

Adsorption Of Salicylhydroxamic Acid On Selected Rare Earth Oxides And Carbonates, Greer Galt

Graduate Theses & Non-Theses

Adsorption behavior of the anionic collector salicylhydroxamic acid (SHA) on a selected group of rare earth oxides (REOs) and carbonates (RECs) was studied via experimental methods and modelling software. Synthetic oxide and carbonate powders of the rare earth elements cerium (Ce), praseodymium (Pr), europium (Eu), and terbium (Tb) were tested for this research. Studies were conducted at different pH levels to analyze the kinetics of collector adsorption onto the oxide and carbonate surfaces in attempts to optimize recovery parameters for commercial flotation processes using SHA. In addition, thermodynamic software StabCal was implemented to compare theoretical adsorption behavior of collectors SHA …

Encapsulation Process Of Propolis Extract By Casein Micelle Improves Sunscreen Activity, Muhamad Sahlan, Dara Dienayati, Darul Hamdi, Soraya Zahra, Heri Hermansyah, Malyn Chulasiri

Makara Journal of Technology

Propolis, a wax bee glue, have antioxidant activity and effective as broad spectrum UVB and UVA photoprotection sunscreens agent. To improve photoprotection activity in sunscreen cream, the propolis was encapsulated by casein micelle. The Indonesian propolis was extracted by ethanol and separated the wax by freeze precipitation. The extract was encapsulated by casein and reduced their size by ball mill homogenizer with the encapsulation efficiency about 80% and size of particles about 80 nm. The particles was applied in sunscreen cream, evaluate their stabillity and photoprotection activity Sun Protection Factor (SPF) spectrophotometer (Optometric 290s). The results shows that the selected …

Synthesis Of Libob Fine Powder To Increase Solubility, Etty Marti Wigayati, Titik Lestariningsih, Christin Rina Ratri, Ibrahim Purawiardi, Bambang Prihandoko

Makara Journal of Technology

Lithium bis (oxalate) borate or LiBOB compound has captured interest of researchers, because it is potentially viable to be used as electrolyte salt in lithium-ion battery system. This compound is easy to synthesize and considered to be more environmentally friendly compared to conventional electrolyte salt because LiBOB does not contain halogen element. This research focused on the synthesis of LiBOB fine powder, which main purpose is improving LiBOB salt solubility in liquid electrolyte solution. This will aid the ion transfer between electrodes which in turn will increase the electrolyte performance. Solid state reaction was employed in this experiment. Synthesis of …

The Impact Of A Dynamic Environment On Deposition And Cellular Response To Silver Nanoparticles, Robert F. Uhrig

Honors Theses

Silver nanoparticles (AgNPs) are utilized in many different applications, such as an antibacterial agents or as protective coating against ultraviolet light. However, these AgNPs are known to cause potentially harmful biological effects, including toxicity, induction of stress, and immune activation. In this study, the effects of AgNPs on a human lung cell model were examined within both a static and dynamic environment. Most NP-based research is carried out in static environments, but do not accurate reflect dynamic physiological conditions. Dynamic fluid movement was introduced to the cell culture through the use of a multi-channel peristaltic pump. To further characterize the …