Materials Science and Engineering Commons^™

Development Of Many-Body Potential For Deformation Study In Al-Tin Nanolayered Composites, Paul Yaohan Simanjuntak

Graduate Theses/Dissertations

A novel interatomic potential of ternary Al-Ti-N has been developed to study the deformation behavior of Al-TiN nanolaminates. The ternary nanolayered Al-TiN composite has attracted a lot of interest due to its combination of strength and ductility. The current analysis on the system has been primarily concentrated on continuum models which are inadequate to explain the key deformation events such as nucleation and interaction of dislocations. Progress in the preferred atomistic approach has been hampered however by the lack of available interatomic potential optimized for the ternary system. I developed a many-body potential based on embedded atomic model (EAM) by …

Experimental And Theoretical Study Of Vapor Phase Species Above Hot Rocky Exoplanet Analogues, Michal Bulak

Graduate Theses/Dissertations

With the James Webb Space Telescope and other space-based missions launching in the next few years, the astrophysics community awaits an exciting time. This work is an answer to a call for the laboratory contributions necessary to analyze the data of unprecedented accuracy. I performed a laboratory analysis of an analogue of a hot super earth atmosphere. This type of an extra solar planet has a rocky composition and has extremely high temperature (from 1500˚C – 5000˚C). I performed infrared spectroscopy on the gas phase vapor above a mixture of two binary systems: SiO2 with Al2O3 and CaO with SiO2. …

Development And Degradation Analysis Of Novel Micro And Nanostructured Transition Metal Oxide (Tmo) Anodes For Aqueous Sodium Ion Batteries., Santanu Mukherjee

Electronic Theses and Dissertations

One of the primary motivations driving battery technology research is the need to develop cleaner and more efficient energy storage systems. The portable electronics industry has developed exponentially, especially over the last couple of decades and therefore the importance of efficient electrochemical energy storage systems cannot be overstated. Li-ion batteries have been the predominant rechargeable energy in use, however, they have their own particular drawbacks viz. flammability of the electrolyte, expensive mining of the Li metal etc. This is where the importance of Na-ion batteries lie. This research focuses on using existing transition metal oxides (TMOs) and tuning their crystal …

Re-Evaluation Of Acceptance Testing Criteria For Structural Masonry Using The Prism Test Method, James Bristow

UNLV Theses, Dissertations, Professional Papers, and Capstones

The current acceptance criteria for structural masonry in accordance with International Building Code allows for the prism test method to be used. However, without a proper understanding of the effects of variable material properties such as individual masonry unit compressive strength and the various material moduli of elasticity, as well as the effect of field conditions on the unit’s performance, masonry prisms may “fail” to reach the design compressive strength (f’m).

By identifying causes of failure and evaluating the failure magnitude, it is concluded that when the masonry prism test method is utilized for acceptance testing of as-built masonry structures, …

High Early-Age Strength Concrete For Rapid Repair, Matthew O. Maler

UNLV Theses, Dissertations, Professional Papers, and Capstones

The aim of this research was to identify High Early-Age Strength (HES) concrete batch designs, and evaluate their suitability for use in the rapid repair of highways and bridge decks. To this end, two criteria needed to be met; a minimum compressive strength of 20.68 MPa (3000 psi) in no later than 12 hours, and a drying shrinkage of less than 0.06 % at 28 days after curing. The evaluations included both air-entrained, and non-air-entrained concretes.

The cement types chosen for this study included Type III and Type V Portland cement and “Rapid Set” − a Calcium Sulfoaluminate (CSA) cement. …

Polyisobutylene Telechelic Prepolymers By In Situ End-Quenching And Post-Polymerization Modifications, Bin Yang

Dissertations

This volume focuses on the development of telechelic polyisobutylene (PIB) prepolymers by combining end-capping of living carbocationic polymerization of isobutylene (IB) with suitable reactants and post-polymerization modifications. Alkylation kinetics of PIB tert-chloride with alkoxybenzenes using either TiCl₄ or AlCl₃ were investigated. Quantitative para-position end-capped products were only achieved if the alkoxybenzene/AlCl₃ molar ratio was greater than unity; while no such molar ratio is required for TiCl₄, but the alkylation rate was slower than AlCl₃ under the same conditions. Photopolymerization kinetics analysis of PIB triphenol tri(meth)acrylates with low and high M_ns, …

The Role Of Ceramic And Glass Science Research In Meeting Societal Challenges: Report From An Nsf-Sponsored Workshop, Katherine T. Faber, Tewodros Asefa, Monika Backhaus-Ricoult, Richard K. Brow, Julie Y. Chan, Shen Dillon, William Fahrenholtz, For Full List Of Authors, See Publisher's Website.

Materials Science and Engineering Faculty Research & Creative Works

Under the sponsorship of the U.S. National Science Foundation, a workshop on emerging research opportunities in ceramic and glass science was held in September 2016. Reported here are proceedings of the workshop. The report details eight challenges identified through workshop discussions: Ceramic processing: Programmable design and assembly; The defect genome: Understanding, characterizing, and predicting defects across time and length scales; Functionalizing defects for unprecedented properties; Ceramic flatlands: Defining structure-property relations in free-standing, supported, and confined two-dimensional ceramics; Ceramics in the extreme: Discovery and design strategies; Ceramics in the extreme: Behavior of multimaterial systems; Understanding and exploiting glasses and melts under …

Jet Bounce In Low Gravity, Caleb Turner

Maseeh Summer Undergraduate Research Experience

Liquid jets rebound (‘bounce’) from superhydrophobic surfaces when they impinge at oblique angles. We call this interesting phenomena ‘jet bounce’ and in this work we investigate the phenomena at large length scales in a reduced gravitational environment. For example, for water at Reynolds numbers 0 < Re < 3500 and surface normal Weber numbers 0 < We < 60 we characterize the response of the jets on the hydrophobic surface in the brief 2.1s micro-gravity environment achieved using a drop tower. It is observed that by varying jet velocity, flow rate, jet diameter, and incident angle we observe up to four distinct regimes of behavior. The various regimes may be targeted for specific applications and we demonstrate a variety of unique jet bounce behaviors for applications such as no-touch, no-contact fluid-thermal transport for spacecraft unit operations such as contaminated water processing, device cooling, and cryogenic fluids transport and management.

Stable jet bounce from small diameter jet ≈ 1 mm and low impact angle. Characterizing Reynolds number ≈ 900 and normal Weber number ≤ 10 allow jet bounce to rebound in non-destructive behavior.

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.

Computational Modeling Of Electrical And Phonon Properties Of Skutterudites And Two-Dimensional Transition Metal Dichalcogenides, Izaak Gene Williamson

Boise State University Theses and Dissertations

This dissertation documents the computational modeling of skutterudite and two-dimensional transition metal dichalcogenide (2D TMD) materials for energy and electronic applications by analyzing the effects of materials doping and heterostructure formation on structural, energetic, electrical, phonon, and thermal properties. These topics remain largely unexplored and can accelerate materials development by providing insight on structure-properties-performance relationships.

Skutterudites are commonly studied for thermoelectric applications because they are low-cost, easy to process, and offer good intrinsic transport properties. They also exist as large, open structures which can be altered through filler atoms or substitutional dopants. A density functional theory (DFT)-based investigation of dopant …