Engineering Commons^™

Prediction Of Dopant Ionization Energies In Silicon: The Importance Of Strain, A. Rockett, Duane D. Johnson, S. V. Khare, B. R. Tuttle

Duane D. Johnson

Based on a hydrogenic state and strain changes upon defect charging, we propose a simple, parameter-free model that agrees well with the observed group III and V monovalent-impurity ionization energies in Si, revealing the importance of such strain effects. Changes in lattice strain upon defect charging are obtained via superposition and elasticity theory using atomic relaxations from density functional theory.

Afci Quarterly Input – Unlv October Through December, 2003, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects and objectives of the Transmutation Research Program at the Nuclear Science & Technology Division, Harry Reid Research Center.

The University of Nevada, Las Vegas supports the AFCI through research and development of technologies for economic and environmentally sound refinement of spent nuclear fuel. The UNLV program has four components: infrastructure, international collaboration, student-based research, and management and program support.

Identification Of Dynamic Properties Of Materials For The Nuclear Waste Package, Brendan O'Toole, Mohamed Trabia, Amy J. Smiecinski

Publications (YM)

Stainless steel 316L, titanium alloy grade 7, and alloy C22 are currently under consideration as candidate materials for use in various components associated with the spent nuclear fuel package, which must be designed to withstand structural deformation caused by static, thermal, and handling loads. In addition, it has to maintain its integrity in case of accidents, where it may be subjected to high loads over a very short period of time. Mechanical characteristics of these three materials under dynamic loading are not well documented. This paper describes the procedures and results obtained from experiments performed over a range of slow …

Examination Of Focused Beam Propagation Through A Finite Non-Reciprocal Planar Chiral Slab Using Complex Fresnel Coefficients And Dual Transforms, Monish Ranjan Chatterjee, Sumit Nema, Partha P. Banerjee

Electrical and Computer Engineering Faculty Publications

Recently, uniform plane wave propagation across a nonchiral-chiral interface was examined via the development of appropriate Fresnel coefficients. In this extension, propagation of focused uniform and profiled beams through a finite, planar nonreciprocal chiral slab is investigated using complex Fresnel coefficients via angular plane wave decomposition and dual transforms.

Task 32 Delayed Hydride Cracking Of Spent Fuel Cladding Under Repository Conditions, Ajit K. Roy, Anthony Hechanova, Amy J. Smiecinski

Publications (YM)

The objective of this quality-affecting task is to evaluate the susceptibility of spent nuclear fuel cladding materials (zirconium alloys) to stress corrosion cracking (SCC), delayed hydride cracking (DHC) and localized corrosion (pitting/crevice) in simulated repository environments. During the first year of this project, major efforts were focused on developing the infrastructure for performing the desired testing involving two highly corrosion-resistant alloys namely, zircaloy-2 (Zr-2) and zircaloy-4 (Zr-4) in simulated concentrated acidic water (SAW) and modified SAW (SAWM). Modification of the SAW chemistry was done by adding hydrochloric acid (HC1) to achieve lower pH. The construction of the "Materials Performance Laboratory …

Afci Quarterly Input – Unlv July Through September, 2003, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects and objectives of the Transmutation Research Program at the Nuclear Science & Technology Division, Harry Reid Research Center.

The University of Nevada, Las Vegas supports the AFCI through research and development of technologies for economic and environmentally sound refinement of spent nuclear fuel. The UNLV program has four components: infrastructure, international collaboration, student-based research, and management and program support.

Design And Analysis For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides: Quarterly Progress Report 5/16/03- 8/15/03, Yitung Chen, Randy Clarksean, Darrell Pepper

Fuels Campaign (TRP)

The analysis of mold filling and solidification continues with progress being made for the consideration of these two features within one model. Analysis of the induction heating process of an Induction Skull Melter (ISM) is under study. Efforts are underway to validate the modeling procedure and specific comparisons are being made to previously published work. Few detailed modeling results have been reported by other researchers, making the validations an important part of the overall modeling process. Skin heating depths, power deposition rates, and other process parameters are being evaluated for use in upcoming furnace design simulations. Efforts are beginning on …

Competition Between Ferromagnetism And Antiferromagnetism In Fept, G. Brown, B. Kraczek, A. Janotti, T. C. Schulthess, G. M. Stocks, Duane D. Johnson

Duane D. Johnson

Ni/Fe/Co/Cu(100) films were epitaxially grown and investigated by photoemission electron microscopy. The magnetic correlation of the Ni and Co films was investigated by element-specific domain images. We found that the Ni magnetization exhibits a continuous rotation in the spin reorientation transition (SRT) region and that the Ni SRT thickness oscillates with the Fe film thickness.

Revisiting The Fresnel Coefficients For Uniform Plane Wave Propagation Across A Nonchiral, Reciprocal And Chiral, Nonreciprocal Interface, Monish Ranjan Chatterjee, Sumit Nema

Electrical and Computer Engineering Faculty Publications

The problem of EM wave propagation in non-reciprocal chiral media has been studied by several investigators. In a recent approach, a dual-transform technique has been developed to study the problem of such propagation under paraxial and slow-envelope variation conditions.

In this paper, we first outline some of the results obtained using the dual transform technique for arbitrary boundary conditions within the left boundary of a semi-infinite, non-reciprocal chiral medium for a uniform plane wave, and a fundamental Gaussian-profiled beam. Next, we explore the problem of a uniform EM wave incident at an oblique angle at an interface between a reciprocal, …

45th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 45th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-endorsed by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 27-31, 2003.

Comment On: 'Depolarization Corrections To The Coercive Field In Thin-Film Ferroelectrics', Stephen Ducharme, Vladimir Fridkin

Stephen Ducharme Publications

The Letter by Dawber et al. [J. Phys.: Condens. Matter 15 L393 (2003)] notes that incomplete screening in the electrodes of a ferroelectric capacitor can result in an underestimate for the true coercive field in films of nanometer thickness. We show that their estimate of the magnitude of this correction it too large in the case of ferroelectric copolymer Langmuir- Blodgett films and, as a result, invalidates the claim that finite-size scaling of the ferroelectric coercive field is evident in films thinner than 15 nm.

Phase Ii: Design And Analysis Of A Process For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Yitung Chen, Randy Clarksean, Darrell Pepper

Fuels Campaign (TRP)

This research report develops a model to analyze the transport of americium from the melt to the vapor phase above the crucible. The model considers mass transport in the melt, vaporization at the surface, and transport through the vapor phase. The greatest problem with the model is the uncertainty of the thermodynamic properties of the proposed ternary alloy. The details of the model and the specific quantities needed for the physical properties will be discussed.

Предсказание Термодинамики И Упорядочения В Металлических Сплавах Из Первых Принципов, Николай Заркевич

Nikolai A. Zarkevich

Кластерные разложения по взаимодействиям все чаще используются для много- масштабного моделирования, сочетающего расчёты электронной структуры из первых принципов и методы Монте-Карло для предсказания термодинамических свойств сплавов. Кластерное разложение – это разложение по базису геометрических объектов (кластеров) на решётке и эффективных межатомных взаимодействий. Кластерное разложение может быть математически точным и бесконечным, но практично только в усечённом конечном базисе. Однако до сих пор процедура усечения базиса не была строго определена и не гарантировала надёжный результат. Мы предлагаем метод оптимального усечения базиса геометрических кластеров, который ведёт к надёжным предсказаниям термодинамики. Далее для примера мы проводим количественный расчёт термодинамических свойств ГЦК сплава Ni3V и …

Afci Quarterly Input – Unlv April Through June, 2003, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

The University of Nevada, Las Vegas supports the AFCI through research and development of technologies for economic and environmentally sound refinement of spent nuclear fuel. The UNLV program has four components: infrastructure, international collaboration, student-based research, and management and program support.

Unlv Transmutation Research Program Proposal Year Iii: Design And Evaluation Of Processes For Fuel Fabrication, Georg F. Mauer

Fuels Campaign (TRP)

The objective of this project is the design and evaluation of manufacturing processes for transmuter fuel fabrication. The large-scale deployment of remote fabrication and refabrication processes will be required for all transmutation scenarios. Current program emphasis is on a five-year effort to determine the feasibility of transmutation as a technology to limit the need for repository storage of spent commercial fuel. The evaluation of the fabrication processes will create a decision support data base to document design, operations, and costs. Fabrication processes required for different fuel types differ in terms of equipment types, throughput, and cost. Differential cost Implications of …

Design And Analysis For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides: Quarterly Progress Report 2/16/03- 5/15/03, Yitung Chen, Randy Clarksean, Darrell Pepper

Fuels Campaign (TRP)

Progress continues on the analysis of casting and solidification of the melt into molds. Modeling results for constant pressure casting, which is more realistic, have been obtained and produce physically realistic results for flow that starts, flows, and then eventually stops as it enters the mold. Potential mass transfer modeling features (Lammuir’s law for example) are being studied to enhance the capabilities of a mass transfer in a detailed system model. Different parameters are being varied as part of a parametric study to evaluate factors that impact the flow of the melt into the molds. The ability to include the …

Reply To “Comment On ‘Classical Density Functional Theory Of Freezing In Simple Fluids: Numerically Induced False Solutions’ ”, M. Valera, F. J. Pinski, Duane D. Johnson

Duane D. Johnson

Recently we solved, via discrete numerical grids, the Ramakrishna-Yossouff density-functional theory equations for the freezing transition and obtained an intricate phase diagram of hard-sphere mixtures. Even though such methods provide more variational freedom than basis-set methods, we found that the thermodynamic quantities were sensitive to the spacing of numerical grids employed and observed numerically induced false minima. Dasgupta and Valls have commented that these false minima were due to our use of k-space methods and, hence, their early works based on a fully r-space approach are qualitatively correct, despite also being sensitive to the mesh granularity. Here, we clarify the …

Optimal Beam Splitters For The Division-Of-Amplitude Photopolarimeter, R. M.A. Azzam, A. De

Electrical Engineering Faculty Publications

Optimal optical parameters of the beam splitter that is used in the division-of-amplitude photopolarimeter are determined. These are (1) 50%–50% split ratio of the all-dielectric beam splitter, (2) differential phase shifts in reflection and transmission Δ_r and Δ_t that differ by ±π/2, and (3) ellipsometric parameters (ψ_r, ψ_t)= (27.368°, 62.632°) or (62.632°, 27.368°). It is also shown that for any nonabsorbing beam splitter that splits incident unpolarized light equally, the relationship ψ_r+ψ_t=π/2 is always satisfied.

Evolution Of The Band Structure Of Β-In2 S3−3x O3x Buffer Layer With Its Oxygen Content, N. Barreau, S. Marsillac, J. C. Bernède, L. Assmann

Electrical & Computer Engineering Faculty Publications

The evolution of the band structure of β-In2 S3−3x O3x (BISO) thin films grown by physical vapor deposition, with composition x, is investigated using x-ray photoelectron spectroscopy. It is shown that the energy difference between the valence-band level and the Fermi level remains nearly constant as the optical band gap of the films increases. As a consequence, the difference between the conduction band level and the Fermi level increases as much as the optical band gap of the films. The calculation of the electronic affinity [ ] of the BISO thin films shows that it decreases linearly from 4.65 …

Wide Angle Achromatic Prism Beam Steering For Infrared Countermeasures Applications, Bradley D. Duncan, Philip J. Bos, Vassili Sergan

Electro-Optics and Photonics Faculty Publications

The design and analysis of achromatic doublet prisms for use in laser beam steering is presented. The geometric relationships describing the maximum steering angle are given, as are discussions of first- and second-order dispersion reduction. Infrared (IR) material alternatives and optimum IR material characteristics for wide-angle achromatic prism beam steering are also investigated. Sixteen materials in 120 different combinations have been examined to date. For midwave IR applications it is shown that the minimum dispersion currently achievable across the full 2 to 5 μm spectrum is 1.7816 mrad at an average maximum steering angle of 45 deg. This is accomplished …

Field Emission Based Sensors Using Carbon Nanotubes, Changkun Dong

Physics Theses & Dissertations

A number of sensitive applications would be greatly benefited by the development of better cold cathodes that employ the electron field emission process. Among the many kinds of field emitters that could be tried, carbon nanotubes (CNT) have a number of distinct advantages because of their unique geometrical structure, chemical inertness, mechanical stiffness, and high thermal and electrical conductivities. This dissertation describes research in which CNT cathodes were fabricated and their emission characteristics were measured.

Multi-walled carbon nanotubes (MWNT) were grown by chemical vapor deposition (CVD) on various substrates: Ni and Hastelloy gauze, 304 stainless steel (SS) plates, and Ni-coated …

Dynamics Of Phase Transitions On Low-Index Metal Surfaces, Bo Lin

Electrical & Computer Engineering Theses & Dissertations

The surface superheating and phase transitions at the low-index surface of metal were investigated using conventional continuous and 100-ps time-resolved reflection high-energy electron diffraction. Three metal surfaces, In(111), Au(110) and Pb(111), have been investigated in this work. The high temperature behavior of the In(111) surface was investigated using reflection high-energy electron diffraction with 100-ps temporal resolution. The change of surface vacancy density on In(111) is observed from 300 K to near the bulk melting point. The vacancy-formation energy of In(111) surface is estimated from experimental results. The surface vacancy density is observed to increase with temperature; however, the average random …

Afci Quarterly Input – Unlv January Through March, 2003, Harry Reid Center For Environmental Studies. Nuclear Science And Technology Division

Transmutation Research Program Reports (TRP)

Quarterly report highlighting research projects and objectives of the Transmutation Research Program at the Nuclear Science & Technology Division, Harry Reid Research Center.

Quantum Mechanical Calculations Of Monoxides Of Silicon Carbide Molecules, John W. Roberts Jr.

Theses and Dissertations

Modern semiconductor devices are principally made using the element silicon. In recent years, silicon carbide (SiC), with its wide band-gap, high thermal conductivity, and radiation resistance, has shown prospects as a semiconductor material for use in high temperature and radiation environments such as jet engines and satellites. A limiting factor in the performance of many SiC semiconductor components is the presence of lattice defects formed at oxide dielectric junctions during processing. Recent theoretical work has used small quantum mechanical systems embedded in larger molecular mechanics structures to attempt to better understand SiC surfaces and bulk materials and their oxidation. This …

Detection Of Special Nuclear Material With High Purity Germanium (Hpge) And Mercuric Iodide (Hgi2) Gamma Detectors, Michael B. Nelson

Theses and Dissertations

The Defense Threat Reduction Agency (DTRA) contracted for two gamma radiation detectors: mercuric iodide (HgI₂) and electromechanically cooled (EMC) high purity germanium (HPGe) to support arms control inspection efforts. This project investigated whether these detectors could measure the quality and quantity of special nuclear material (SNM), particularly Pu-239 for the treaty verification mission. The project investigated two areas of detector capabilities: 1) HgI₂ and HPGe detector performance necessary to characterize the quality of plutonium and the presence of shielding materials and 2) HgI₂ and EMC HPGe detector performance degradation by high noise levels and EMC HPGe …

Design And Analysis Of A Process For Melt Casting Metallic Fuel Pins Incorporating Volatile Actinides, Yitung Chen, Darrell Pepper, Randy Clarksean

Fuels Campaign (TRP)

UNLV has developed and will continue to develop process models for the analysis of melt casting processes. This work will continue to be performed under the guidance of Argonne National Laboratory (ANL) engineers to insure that their knowledge and experience benefits the project. The research to be conducted during year three will center on performing detailed analyses on a conceptual design of an inductively heated skull-crucible casting furnace. Processing conditions will be analyzed, basic models utilized, and detailed heat and mass transfer models will be developed to analyze the most promising processes. The goal of this third year is to …

Experimental Investigation Of Steel Corrosion In Lead Bismuth Eutectic (Lbe): Characterization, Species Identification, And Chemical Reactions, John Farley, Dale L. Perry, Allen L. Johnson

Transmutation Sciences Materials (TRP)

The goal of the present research is to achieve a basic understanding of corrosion of steels by Lead Bismuth Eutectic (LBE). Liquid LBE is under consideration in the transmuter as both a spallation target and as a blanket coolant. There have been previous studies of LBE, especially by the Russians, who have over 80 reactor-years experience with LBE coolant in their Alpha-class submarine reactors. The Russians found that the presence of small amounts (ppm) of oxygen in the LBE significantly reduced corrosion. However, a fundamental understanding and verification of its role in the corrosion of steels is still very incomplete. …

Predicted Hcp Ag-Al Metastable Phase Diagram, Equilibrium Ground States, And Precipitate Structure, Nikolai A. Zarkevich, Duane D. Johnson

Nikolai A. Zarkevich

Formation energies of a number of hcp-based Ag-Al structures are obtained from ab initio electronic-structure calculations and used within a cluster expansion approach to construct an effective alloy Hamiltonian. Formation energies are found to be inherently asymmetric versus composition, providing an incipient tendency for precipitation in Al-rich alloy. Both ground-state search and Monte Carlo simulations based on the cluster expansion are used to determine the metastable hcp Ag-Al phase diagram. A new equilibrium hcp AgAl ground state is predicted and zero-energy domain boundary defects are found. From thermodynamic results, we discuss the precipitate structure and composition in Al-rich Al-Ag alloys …

University Of Nevada, Las Vegas Transmutation Research Program: Quarterly Report, Second Quarter Year 2 (June 2002 To August 2002), Anthony Hechanova

Transmutation Research Program Reports (TRP)

This Quarterly Report is a primary deliverable from the University of Nevada, Las Vegas (UNLV) Transmutation Research Program (TRP) Director to the U.S. Department of Energy (DOE) as described in the UNLV Advanced Accelerator Applications (AAA) proposal, and AAA FY02 Work Package. Note: during this quarter, the AAA national program changed names to the Advanced Fuel Cycle Initiative (AFCI) and the UNLV AAA University Participation Program changed its name to the Transmutation Research Program. The new names will be used in future references.

The TRP Director implements the program’s administration using staff from the Harry Reid Center for Environmental Studies …

Corrosion Of Steel By Lead Bismuth Eutectic: Quarterly Report November- December 2002 January 2003, John Farley

Transmutation Sciences Materials (TRP)

We continue to get valuable data from sputter depth profiling of steel samples. We meet weekly to discuss progress. We took depth-profiling data on D9 steel that had been exposed to LBE. This the first time we have examined this type of steel. This is important because it will enable us to separate out two effects and determine their effect on corrosion: composition of the steel vs surface preparation.

We started to plan a small experiments using a crucible of heated LBE, with the research program to be conducted at UNLV, on basic aspects of corrosion in this system. The …