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Full-Text Articles in Engineering Science and Materials

Defect Chemistry And Ion Intercalation During The Growth And Solid-State Transformation Of Metal Halide Nanocrystals, Bo Yin May 2019

Defect Chemistry And Ion Intercalation During The Growth And Solid-State Transformation Of Metal Halide Nanocrystals, Bo Yin

Engineering and Applied Science Theses & Dissertations

Abstract of the Dissertation

Defect Chemistry and Ion Intercalation During the Growth and Solid-State Transformation of Metal Halide Nanocrystals

Semiconductor metal halides as light-sensitive materials have applications in multiple areas, such as photographic film, antibacterial agents and photocatalysts. One focus of this dissertation is to achieve novel morphologies of ternary silver bromoiodide (AgBr1-xIx, 0

For the silver halide system, we demonstrate that the anion composition of AgBr1-xIx nanocrystals determines their shape through the introduction of twin defects as the nanocrystals are made more iodide-rich. AgBr1-xIx nanocrystals grow as single-phase, solid solutions with the rock salt crystal structure for anions compositions ...


The Role Of Vec And Local Atomic Environment In Structural Transitions And Stability Of Complex Intermetallic Compounds Through Theoretical And Experimental Study Of Γ-Brasses, Stephanie L. Eveland Jan 2019

The Role Of Vec And Local Atomic Environment In Structural Transitions And Stability Of Complex Intermetallic Compounds Through Theoretical And Experimental Study Of Γ-Brasses, Stephanie L. Eveland

Graduate Theses and Dissertations

The fusion of computational and synthetic techniques provides a powerful investigative arsenal for a systematic consideration of the factors governing the structural makeup and observed physical properties of complex intermetallic compounds such as the non-uniform mixed sites in Mn2+xZn11-x, VEC driven structural transition in Mn5-yAl8-xZnx+y, and atypical atomic decoration of Cu9Al4 γ-brasses. Classic solid state synthetic techniques, self-flux techniques, as well as multiple structural characterization methods such as X-ray diffraction and electron microscopy were employed in the experimental portion of this work. Magnetic susceptibility measurements were utilized when appropriate in the study of the γ- brasses of Mn2 ...


Call For Abstracts - Resrb 2019, July 8-9, Wrocław, Poland, Wojciech M. Budzianowski Dec 2018

Call For Abstracts - Resrb 2019, July 8-9, Wrocław, Poland, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Optimization Of Useful Hard X-Ray Photochemistry, David Lewis Goldberger Dec 2018

Optimization Of Useful Hard X-Ray Photochemistry, David Lewis Goldberger

UNLV Theses, Dissertations, Professional Papers, and Capstones

X-ray induced damage is generally considered a nuisance, but in the field of Useful Hard X-ray Photochemistry we harness the highly ionizing and penetrating properties of hard X-rays (> 7 keV) to initiate novel photochemical decomposition and synthesis at ambient and extreme conditions. Preliminary experiments suggest that the energy of irradiating photons and the sample pressure play roles in determining the nature of X-ray induced damage. Here, we present the X-ray energy dependence of damage induced in strontium oxalate, strontium nitrate, and barium nitrate, as well as the pressure dependence of X-ray induced damage of strontium oxalate. Our results indicate that ...


Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman Oct 2018

Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman

Chemistry Faculty Publications

Heterogeneous photocatalysis is a prominent area of research with major applications in solar energy conversion, air pollution mitigation, and removal of contaminants from water. A large number of scientific papers related to the photocatalysis field and its environmental applications are published in different journals specializing in materials and nanomaterials. However, many problems exist in the conception of papers by authors unfamiliar with standard characterization methods of photocatalysts as well as with the procedures needed to determine photocatalytic activities based on the determination of “apparent quantum efficiencies” within a wavelength interval or “apparent quantum yields” in the case of using monochromatic ...


Pnnl Dark Matter Bubble Chamber, Ryan Robinson Aug 2018

Pnnl Dark Matter Bubble Chamber, Ryan Robinson

STAR (STEM Teacher and Researcher) Presentations

The Pacific Northwest National Laboratory (PNNL) prototype bubble chamber is intended to address issues encountered with the current PICO dark matter search detectors and improve the functionality of future experimental designs. The PNNL bubble chamber accomplishes this with a simplified interface between the hydraulic pressure controls and the target vessel and altering the standard chamber design such that it can be easily exchanged and replaced with vessels of various sizes and materials for testing purposes. The chamber itself is a glass vessel which houses perfluorobutane and holds the target fluid above room temperature and atmospheric pressure. The target fluid becomes ...


Lithium And The Foreseeable Future, Paolo Vargas May 2018

Lithium And The Foreseeable Future, Paolo Vargas

Mechanical Engineering Undergraduate Honors Theses

This paper aims to clarify the uncertainties regarding worldwide lithium resource availability in the years to come. Previous studies made on the subject are presented with some ambiguity and this work intends to fill the gaps. The information and data presented throughout this script with respect to global lithium resources and reserves are mostly based on data released by the United States Geological Survey (USGS). Lithium resource availability in the future is a point of paramount significance primarily for the automotive, portable electronics, and the power generation industry. Since, a change of supply would ultimately affect the price of lithium ...


Nanoscale Mechanisms For High-Pressure Mechanochemistry: A Phase Field Study, Mahdi Javanbakht, Valery I. Levitas Mar 2018

Nanoscale Mechanisms For High-Pressure Mechanochemistry: A Phase Field Study, Mahdi Javanbakht, Valery I. Levitas

Aerospace Engineering Publications

Coupled evolution of a high-pressure phase (HPP) and dislocations, including dislocation pileups and dislocations generated due to phase transformation (PT), under compression and shear of a nanograined bicrystal, is considered as a model for high-pressure mechanochemistry. Recently developed phase field approach for the interaction between PTs and dislocations at large strains and a finite element analysis are utilized. Periodic boundary conditions for displacements are applied to the lateral surfaces. It is confirmed that the shear-induced dislocation pileups may reduce the PT pressure by an order of magnitude in comparison with hydrostatic loading, and even below phase equilibrium pressure, as it ...


Books Published By Métallurgie Extractive Québec, Fathi Habashi Mar 2018

Books Published By Métallurgie Extractive Québec, Fathi Habashi

Fathi Habashi

A condensed catalog of books published by Métallurgie Extractive Québec - - a non-profit publisher devoted to the diffusion of extractive metallurgy literature.


Controlled Folding In Precisely Functionalized Polyethylenes: Designing Nanoscale Lamellar Structures For Ion Transport, Edward Boynton Trigg Jan 2018

Controlled Folding In Precisely Functionalized Polyethylenes: Designing Nanoscale Lamellar Structures For Ion Transport, Edward Boynton Trigg

Publicly Accessible Penn Dissertations

There is great societal need for improved energy storage technology, in applications ranging from electric vehicles to grid storage to emergency power systems. New polymeric membranes with enhanced ion conductivities are needed in batteries and fuel cells to improve these technologies. Despite decades of research, these membrane materials are still not adequate for commercial use. The primary metric that requires improvement is ion or proton conductivity of the membrane under desirable operating conditions.

Modifying linear polyethylene by the addition of precisely periodic functional groups leads to a rich array of intriguing morphologies and properties. Depending on the functional group chemistry ...


The Role Of Sliding Contact In Nanoscale Tribochemistry, Zachary Banks Milne Jan 2018

The Role Of Sliding Contact In Nanoscale Tribochemistry, Zachary Banks Milne

Publicly Accessible Penn Dissertations

In this dissertation, the results of experimental and theoretical studies exploring friction

and adhesion at the nanoscale are presented. Using a customized in situ transmission

electron microscopy nanoindentation methodology, it is observed that cohesion of silicon and

adhesion of silicon and diamond are strongly modied by the sliding speed and the normal

stress applied during sliding. This indicates that shear stress modulates the reactivity of the

surfaces. This is the rst time that tunable adhesion of hard contacts has been demonstrated

in situ.

If sliding experiments are performed in ultra-high vacuum and the interfacial shear stress

is low enough to ...


Biorenewable Polymer Thermoplastic Biocomposites, Mitchel M. Michel Jan 2018

Biorenewable Polymer Thermoplastic Biocomposites, Mitchel M. Michel

Graduate Theses and Dissertations

Biorenewable fillers have recently gained a greater focus in research to produce composites because of their unique properties, abundance, and diversity. These biorenewable fillers can include various terrestrial based plants naturally grown throughout the world. The focus of this work was on the natural fiber feedstocks that are created as waste streams from a wide range of industries, in particular agave fibers. Creating a composite composed of fibrous materials would have potential benefits that include cutting costs of composite products, decrease in density, increased strength and durability, and utilizing plant fiber waste streams for cost recovery. However, these natural fibers ...


Investigating Degradation Pathways In Organic Solar Cell Materials, Satvik Shah Jan 2018

Investigating Degradation Pathways In Organic Solar Cell Materials, Satvik Shah

Graduate Theses and Dissertations

Thin film organic solar is a recent technology with tremendous potential – low cost materials, quicker manufacturing processes and synthetic tuning of organic materials to optimize material properties. Cell efficiencies > 12% have already been achieved. But the bottleneck problem this technology faces is instability. Performance of these cells degrades much faster than traditional solar cells. The degradation occurs on exposure to solar radiation, both through extrinsic ingress of moisture and oxygen as well as intrinsic degradation mechanisms.

One of the most common type of thin film organic cell with efficiency ~10% is PTB7:PCBM organic solar cell. Hence I have tried ...


Solution Phase Synthesis And Computational Investigation Of Pnictide Based Nowotny-Juza Phases, Miles Arthur Burris White Jan 2018

Solution Phase Synthesis And Computational Investigation Of Pnictide Based Nowotny-Juza Phases, Miles Arthur Burris White

Graduate Theses and Dissertations

Filled tetrahedral semiconductors comprised of elements from group I, II, and V of the periodic table are of interest to the thermoelectric, photovoltaic, and battery fields due to their tunable electronic structures. However, until recently, the synthesis of these materials in a facile and scalable manner had remained elusive. In this thesis, we demonstrate the solution phase synthesis of three members of this class of compounds (LiZnP, LiCdP, and LiZnSb). Furthermore, we explore the presence of polytypism in these compounds and computationally investigate which additional phases would be expected to display polytypism. Finally, we closely investigate the phase space of ...


Surface And Interface Characterization Of Solution-Processed Metal Oxides And Pedot:Pss Using Photoelectron Spectroscopy, Lynette M. Kogler Dec 2017

Surface And Interface Characterization Of Solution-Processed Metal Oxides And Pedot:Pss Using Photoelectron Spectroscopy, Lynette M. Kogler

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solution-processed materials are appealing for use in printable electronics as a means to lower production costs, but precise control of the process is crucial for achieving the desired properties in the final materials and their interfaces. Electronic interface properties depend on both the involved materials and their fabrication processes, impacting the development and commercialization of these materials. Analyzing the chemical and electronic structure of these materials, particularly at the surfaces and interfaces, is important not only for insuring that the materials have the desired properties, but also for understanding the effects of the fabrication process and how to modify properties ...


Controlled Electrochemical Reduction Of Gold And Palladium Metal Precursors In Polyaniline, Nicole Goodwin Dec 2017

Controlled Electrochemical Reduction Of Gold And Palladium Metal Precursors In Polyaniline, Nicole Goodwin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Polyaniline (PANI) has been extensively studied due to its unique electrochemical properties. The conjugated polymer is conductive with high chemical stability below 100°C, mechanical strength, and large surface area. The applications of PANI have included chemical sensing, corrosion inhibition coatings, light emitting diode and as a substrate for metal composite catalysts. Both chemical and electrochemical methods have been developed and utilized in the synthesis of PANI/metal composites. The simultaneous reduction of aniline and metal precursor produces a composite of PANI encapsulated metal, reducing the active surface area available for catalysis. Alternatively, chemical reduction of the metal precursor into ...


Inkjet Printing Of Ag Nanoparticles Using Dimatix Inkjet Printer, No 2, Ming Yuan Chuang May 2017

Inkjet Printing Of Ag Nanoparticles Using Dimatix Inkjet Printer, No 2, Ming Yuan Chuang

Protocols and Reports

This report describes the rheological analysisof the present Ag nanoparticle ink, and confirms that it is suitable for the piezoelectric drop-on-demand printing for both of 1 pL and 10 pL cartridges. The satellite drops and the splashing on the substrate are also discussed for optimization of the nozzle temperature and the jetting voltage. The minimum horizontal and vertical line widths are shown to be 30 and 40 µm, respectively, but the average minimum single line width is estimated to be ~50 µm. The non-uniform width lines are suggested to arise from the bulge instability. Furthermore, it is indicated that the ...


Metal–Organic‐Framework‐Derived Carbons: Applications As Solid‐Base Catalyst And Support For Pd Nanoparticles In Tandem Catalysis, Xinle Li, Biying Zhang, Yuhui Fang, Weijun Sun, Zhiyuan Qi, Yuchen Pei, Shuyan Qi, Pengyu Yuan, Xuechen Luan, Tian Wei Goh, Wenyu Huang Mar 2017

Metal–Organic‐Framework‐Derived Carbons: Applications As Solid‐Base Catalyst And Support For Pd Nanoparticles In Tandem Catalysis, Xinle Li, Biying Zhang, Yuhui Fang, Weijun Sun, Zhiyuan Qi, Yuchen Pei, Shuyan Qi, Pengyu Yuan, Xuechen Luan, Tian Wei Goh, Wenyu Huang

Chemistry Publications

The facile pyrolysis of a bipyridyl metal‐organic framework, MOF‐253, produces N‐doped porous carbons (Cz‐MOF‐253), which exhibit excellent catalytic activity in the Knoevenagel condensation reaction and outperform other nitrogen‐containing MOF‐derived carbons. More importantly, by virtue of their high Lewis basicity and porous nature, Cz‐MOF‐253‐supported Pd nanoparticles (Pd/Cz‐MOF‐253‐800) show excellent performance in a one‐pot sequential Knoevenagel condensation‐hydrogenation reaction.


C.V. - Wojciech Budzianowski, Wojciech M. Budzianowski Jan 2017

C.V. - Wojciech Budzianowski, Wojciech M. Budzianowski

Wojciech Budzianowski

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Renewable Energy And Sustainable Development (Resd) Group, Wojciech M. Budzianowski Jan 2017

Renewable Energy And Sustainable Development (Resd) Group, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Computational Studies Of Structure–Function Relationships Of Supported And Unsupported Metal Nanoclusters, Hongbo Shi Jan 2017

Computational Studies Of Structure–Function Relationships Of Supported And Unsupported Metal Nanoclusters, Hongbo Shi

Doctoral Dissertations

Fuel cells have been demonstrated to be promising power generation devices to address the current global energy and environmental challenges. One of the many barriers to commercialization is the cost of precious catalysts needed to achieve sufficient power output. Platinum-based materials play an important role as electrocatalysts in energy conversion technologies. In order to improve catalytic efficiency and facilitate rational design and development of new catalysts, structure–function relationships that underpin catalytic activity must be understood at a fundamental level.

First, we present a systematic analysis of CO adsorption on Pt nanoclusters in the 0.2-1.5 nm size range ...


Electronic Structure Studies Of Complex Intermetallic Arsenides And Borides, Laura C. Lutz-Kappelman Jan 2017

Electronic Structure Studies Of Complex Intermetallic Arsenides And Borides, Laura C. Lutz-Kappelman

Graduate Theses and Dissertations

Electronic structure methods were used to investigate bonding, metal-atom site preference, magnetic ordering, and crystal structure in ternary and quaternary intermetallic compounds that include arsenic or boron. Computational methods based on density functional theory were used to investigate the electronic structure and properties of hypothetical compounds closely related to the compounds of interest, in order to investigate the origins of properties that have been observed experimentally.

The Ti-M-Ir-B (M = transition metal) system was investigated through density functional theory (DFT) calculations in collaboration with experimental researchers. Compounds with approximate compositions (TixM1–x)3Ir3B3 were identified in two structures: a hexagonal structure ...


Novel Gold Intermetallics With Unique Properties And Bonding Patterns, Christopher R. Celania Jan 2017

Novel Gold Intermetallics With Unique Properties And Bonding Patterns, Christopher R. Celania

Graduate Theses and Dissertations

Gold has drawn the fascination of society through its brilliant color, malleability, and chemical resistance (hence its chemical nobility) since its discovery in ancient times. Today, this material is still highly coveted by consumers, but also for research within the scientific realm. The inclusion of gold in intermetallics often leads to notably unique structural and bonding features due to the pronounced relativistic effects on its 5d and 6s orbitals. Examples include quasicrystals and their approximants, unique gold clusters such as isolated Au7 clusters in A4Au7X2 (A = K, Rb, Cs; X = Ge, Sn), one dimensional columns such as Au zig-zag chains ...


Analyses Of Densely Crosslinked Phenolic Systems Using Low Field Nmr, Jigneshkumar Patel Jan 2017

Analyses Of Densely Crosslinked Phenolic Systems Using Low Field Nmr, Jigneshkumar Patel

Doctoral Dissertations

A uniform dispersion of reactants is necessary to achieve a complete reaction involving multi-components, especially for the crosslinking of rigid high-performance materials. In these reactions, miscibility is crucial for curing efficiency. This miscibility is typically enhanced by adding a third component, a plasticizer. For the reaction of the highly crystalline crosslinking agent hexamethylenetetramine (HMTA) with a strongly hydrogen-bonded phenol formaldehyde resin, furfural has been traditionally used as the plasticizer. However, the reason for its effectiveness is not clear. In this doctoral thesis work, miscibility and crosslinking efficiency of plasticizers in phenolic curing reactions are studied by thermal analysis and spectroscopic ...


Methods For Producing Graphene From Petroleum By-Products, Eva M. Deemer Jan 2017

Methods For Producing Graphene From Petroleum By-Products, Eva M. Deemer

Open Access Theses & Dissertations

N/A


Studies Of Energy-Relevant Materials By Nuclear Magnetic Resonance, Jinfang Cui Jan 2017

Studies Of Energy-Relevant Materials By Nuclear Magnetic Resonance, Jinfang Cui

Graduate Theses and Dissertations

In this thesis, we have used nuclear magnetic resonance (NMR) as a local probe to microscopically study three different families of energy-relevant complex materials, namely the 122 Fe-based superconductors Ca(Fe1−xCox)2As2, GeTe-based thermoelectric tellurides GeTe and detonation nanodiamond.

In Chapter 3 and Chapter 4, we investigated the Co substitution effects on static and dynamic magnetic properties of the single-crystalline Ca(Fe1−xCox)2As2 (x = 0, 0.023, 0.028, 0.033, 0.059) via 75As NMR and resistivity measurements. Robustness of the Fe magnetic moments was evidenced by only slight decreases of Hint, although TN is strongly suppressed ...


Polar Intermetallic Crystals And Quasicrystals, Minh-Trang Joyce Pham Jan 2017

Polar Intermetallic Crystals And Quasicrystals, Minh-Trang Joyce Pham

Graduate Theses and Dissertations

Two main questions guide these investigations of polar intermetallic compounds: (1) Where are the atoms, based on observed electron densities via diffraction? and (2) What gives rise to the observed structures, based on chemical bonding and electronic structure theory? At nearly equal Au: Al molar ratios, NaZn13-derivatives of Sr/Ca(AuxAl1–x)12–13 show a progression from cubic to tetragonal, to orthorhombic, and then monoclinic symmetry with subtle decreasing Au concentrations, results which reveal preferential ordering of Au and Al to maximize the number of Au–Al (or Al-rich) shortest distances. In the Au-rich region of the Ca–Au ...


Structure-Property Relationships Of Polyisobutylene-Block-Polyamide Thermoplastic Elastomers, Morgan Dunn Heskett Dec 2016

Structure-Property Relationships Of Polyisobutylene-Block-Polyamide Thermoplastic Elastomers, Morgan Dunn Heskett

Master's Theses

Thermoplastic elastomers (TPEs) are a class of polymer fit for a wide variety of applications due to their customizability. In the synthesis of these types of materials, an elastically-performing polymer, deemed the “soft block,” is combined with a stiffer “hard block” polymer, each of which can be selected based on their own specific properties in order to achieve desired material behavior in the final copolymer. Recently, the use of polyisobutylene as a soft block in combination with a polyamide hard block has been investigated for use in TPE synthesis. While the material showed some promising behavior, many properties were still ...


Spray Printing Of Organic Semiconducting Single Crystals, Grigorios-Panagiotis Rigas, Marcia M. Payne, John E. Anthony, Peter N. Horton, Fernando A. Castro, Maxim Shkunov Nov 2016

Spray Printing Of Organic Semiconducting Single Crystals, Grigorios-Panagiotis Rigas, Marcia M. Payne, John E. Anthony, Peter N. Horton, Fernando A. Castro, Maxim Shkunov

Chemistry Faculty Publications

Single-crystal semiconductors have been at the forefront of scientific interest for more than 70 years, serving as the backbone of electronic devices. Inorganic single crystals are typically grown from a melt using time-consuming and energy-intensive processes. Organic semiconductor single crystals, however, can be grown using solution-based methods at room temperature in air, opening up the possibility of large-scale production of inexpensive electronics targeting applications ranging from field-effect transistors and light-emitting diodes to medical X-ray detectors. Here we demonstrate a low-cost, scalable spray-printing process to fabricate high-quality organic single crystals, based on various semiconducting small molecules on virtually any substrate by ...


Survey Of Advanced Nuclear Technologies For Potential Applications Of Sonoprocessing, Floren Rubio, Edward D. Blanford, Leonard J. Bond Sep 2016

Survey Of Advanced Nuclear Technologies For Potential Applications Of Sonoprocessing, Floren Rubio, Edward D. Blanford, Leonard J. Bond

Aerospace Engineering Publications

Ultrasonics has been used in many industrial applications for both sensing at low power and processing at higher power. Generally, the high power applications fall within the categories of liquid stream degassing, impurity separation, and sonochemical enhancement of chemical processes. Examples of such industrial applications include metal production, food processing, chemical production, and pharmaceutical production. There are many nuclear process streams that have similar physical and chemical processes to those applications listed above. These nuclear processes could potentially benefit from the use of high-power ultrasonics. There are also potential benefits to applying these techniques in advanced nuclear fuel cycle processes ...