Stochastic Variations Of Cathodoluminescent Intensity Of Bisphenol/Amine Epoxy Exposed To Energetic Electron Bombardment,
2014
Utah State University
Stochastic Variations Of Cathodoluminescent Intensity Of Bisphenol/Amine Epoxy Exposed To Energetic Electron Bombardment, Justin Christensen, Justin Dekany, Jr Dennison
Presentations
When highly disordered insulating materials are subjected to energetic electron bombardment they can emit photons. This process is termed “cathodoluminescence.” This occurs in the space plasma environment and is an important phenomenon to understand when designing any object to be put into space. Light emitted from spacecraft materials can affect optical detection, and can cause stray-light contamination in space-based observatories. The Materials Physics Group at Utah State University uses an ultra-high vacuum chamber equipped with electron guns and a cryostat to control the sample temperature to simulate the space environment and to observe its affects on sample materials. Previous studies …
Electrostatic Discharge Breakdown Analyses,
2014
Utah State University
Electrostatic Discharge Breakdown Analyses, Sam Hansen, Jr Dennison, Allen Andersen
Presentations
Electrostatic discharge (ESD) and the associated material breakdown is the primary cause for spacecraft damage due to space environment interactions. This phenomenon occurs when the space plasma fluxes charge a craft to high voltages where insulating materials then break down and conduct current. This can damage or destroy onboard electrical systems. This project deals with how suspect materials break down under high voltage exposure. The USU Material Physics Group has acquired hundreds of samples that underwent ESD. The ESD damage sites of these samples have been analyzed for parameters including breakdown size, shape, coloring, and location and material characteristics such …
First-Principles Atomistic Simulations Of Energetic Materials,
2014
University of South Florida
First-Principles Atomistic Simulations Of Energetic Materials, Aaron Christopher Landerville
USF Tampa Graduate Theses and Dissertations
This dissertation is concerned with the understanding of physico-chemical properties of energetic materials (EMs). Recently, a substantial amount of work has been directed towards calculations of equations of state and structural changes upon compression of existing EMs, as well as elucidating the underlying chemistry of initiation in detonating EMs. This work contributes to this effort by 1) predicting equations of state and thermo-physical properties of EMs, 2) predicting new phases of novel EMs, and 3) examining the initial stages of chemistry that result in detonation in EMs. The motivation for the first thrust, is to provide thermodynamic properties as input …
Faraday Cup Designs For High Efficiency Determination Of Energy- And Angular-Resolved Charged Particle Fluxes,
2014
Utah State University
Faraday Cup Designs For High Efficiency Determination Of Energy- And Angular-Resolved Charged Particle Fluxes, Kent Hartley, Jr Dennison
Senior Theses and Projects
In order to build a spacecraft, we must understand how the construction materials will behave in the space environment (i.e. when subjected to the solar wind). The USU Materials Physics Group performs electron emission tests on spacecraft materials in an Ultra-high vacuum (UHV) test chamber (Fig.1). The chamber utilizes Faraday cups (Fig.2) in order to quantify electron flux at a location within the chamber. This measurement is important in characterizing beam profiles of electron guns used in UHV experiments. Perhaps more importantly, the Faraday cups are used to detect secondary electrons (SE) and back-scattered electrons (BSE) emitted from the surface …
Magnetic Properties Of Fe-Doped Mnal,
2014
University of Nebraska-Lincoln
Magnetic Properties Of Fe-Doped Mnal, Priyanka Manchanda, Arti Kashyap, Jeffrey E. Shield, L. H. Lewis, Ralph Skomski
Ralph Skomski Publications
Electronic and magnetic properties of L10-ordered FexMn1−xAl alloys (x = 0, 0.0625, 0.125, 0.1875, 0.5) are investigated by first-principle supercell calculations. Pristine MnAl exhibits robust ferromagnetism involving the dense-packed Mn atoms in (001) planes of the tetragonal structure. Iron substitution for Mn significantly deteriorates the magnetization of the alloy. The reduction is a dilution effect, caused by the relatively small Fe moment of about 1.9 μB per atom, as compared to the Mn moment, which exceeds 2.4 μB. By contrast, 50% Fe substituted for Mn (x = 0.5) …
Marshall Space Flight Center Arc/Flare Test Analysis,
2014
ASRC Federal
Marshall Space Flight Center Arc/Flare Test Analysis, Charles Bowers, Bob Meloy, Malcolm Niedner, Jim Heaney, Rudy Ivancic, Dennis Skelton, Jr Dennison, Justin Dekany, Amberly Evans Jensen, Gregory Wilson, Todd Schneider
Presentations
No abstract provided.
Spin Transfer Of Quantum Information Between Majorana Modes And A Resonator,
2014
University of Nebraska - Lncoln
Spin Transfer Of Quantum Information Between Majorana Modes And A Resonator, Alexey Kovalev, Amrit De, Kirill Shtengel
Department of Physics and Astronomy: Faculty Publications
We show that resonant coupling and entanglement between a mechanical resonator and Majorana bound states can be achieved via spin currents in a 1D quantum wire with strong spin-orbit interactions. The bound states induced by vibrating and stationary magnets can hybridize, thus resulting in spin-current induced 4π-periodic torques, as a function of the relative field angle, acting on the resonator. We study the feasibility of detecting and manipulating Majorana bound states with the use of magnetic resonance force microscopy techniques.
Improved Conductivity Measurements Of Highly Disordered Insulating Materials,
2014
Utah State University
Improved Conductivity Measurements Of Highly Disordered Insulating Materials, Phil Lundgreen, Justin Dekany, Jr Dennison
Presentations
By developing a low-noise, high-voltage battery power supply, system noise has been reduced, increasing accuracy of conductivity measurements of highly disordered insulating materials. The method involves a simple parallel plate capacitor setup with the sample sandwiched between electrodes, a voltage potential applied to one electrode, and a measurement device applied to the back electrode measuring current. Previous methods involved use of a commercial power supply with a claimed low noise and high linearity, but with a low AC output ripple. At high voltages (1000 V), however, the noise became apparent in the readings and an unacceptable uncertainty was introduced in …
Cathodoluminescence Measurements Of Several Bisphenol/Amine Epoxy Samples,
2014
Utah State University
Cathodoluminescence Measurements Of Several Bisphenol/Amine Epoxy Samples, Justin Christensen
Senior Theses and Projects
No abstract provided.
A Low-Power Optical Electron Switch,
2014
Texas A&M University
A Low-Power Optical Electron Switch, Wayne Cheng-Wei Huang, Roger Bach, Peter Beierle, Herman Batelaan
Department of Physics and Astronomy: Faculty Publications
An electron beam is deflected when it passes over a silicon-nitride surface, if the surface is illuminated by a low-power continuous-wave diode laser. A deflection angle of up to 1.2 mrad is achieved for an electron beam of 29 μrad divergence. A mechanical beam-stop is used to demonstrate that the effect can act as an optical electron switch with a rise and fall time of 6 μs. Such a switch provides an alternative means to control electron beams, which may be useful in electron lithography and microscopy.
Large-Scale Solution Synthesis Of Narrow Graphene Nanoribbons,
2014
University of Nebraska–Lincoln
Large-Scale Solution Synthesis Of Narrow Graphene Nanoribbons, Timothy H. Vo, Mikhail Shekhirev, Donna A. Kunkel, Martha D. Morton, Eric Berglund, Lingmei Kong, Peter M. Wilson, Peter A. Dowben, Axel Enders, Alexander Sinitskii
Nebraska Center for Materials and Nanoscience: Faculty Publications
According to theoretical studies, narrow graphene nanoribbons with atomically precise armchair edges and widths of(1.1 eV), which makes them potentially promising for logic applications. Different top–down fabrication approaches typically yield ribbons with width >10nm and have limited control over their edge structure. Here we demonstrate a novel bottom–up approach that yields gram quantities of high-aspect-ratio graphene nanoribbons, which are only ~1 nm wide and have atomically smooth armchair edges. These ribbons are shown to have a large electronic bandgap of ~1.3 eV, which is significantly higher than any value reported so far in experimental studies of graphene nanoribbons prepared by …
Wave Function For Harmonically Confined Electrons In Time-Dependent Electric And Magnetostatic Fields,
2014
Ningbo University
Wave Function For Harmonically Confined Electrons In Time-Dependent Electric And Magnetostatic Fields, Hong-Ming Zhu, Jin-Wang Chen, Xiao-Yin Pan, Viraht Sahni
Publications and Research
We derive via the interaction “representation” the many-body wave function for harmonically confined electrons in the presence of a magnetostatic field and perturbed by a spatially homogeneous time-dependent electric field—the Generalized Kohn Theorem (GKT) wave function. In the absence of the harmonic confinement – the uniform electron gas – the GKT wave function reduces to the Kohn Theorem wave function. Without the magnetostatic field, the GKTwave function is the Harmonic Potential Theorem wave function. We further prove the validity of the connection between the GKT wave function derived and the system in an accelerated frame of reference. Finally, we provide …
Modeling The Defect Density Of States Of Disordered Sio2 Through Cathodoluminescence,
2014
Utah State University
Modeling The Defect Density Of States Of Disordered Sio2 Through Cathodoluminescence, Amberly Evans Jensen
Theses and Dissertations
Spacecraft charging is the accumulation of an electrical charge on orbiting spacecraft induced by the space plasma environment and has harmful effects on the electrical functionality of a spacecraft. This is studied extensively, particularly in the Materials Physics Group (MPG) at Utah State University (USU). During charging studies performed by the MPG, another potentially problematic effect of the space plasma environment on spacecraft was observed: light emanating from the sample undergoing electron beam bombardment. Space-based observatories are one type of spacecraft on which this luminescence may occur. If the luminescence from the material caused by the space plasma is within …
Feasibility Of Detecting Spacecraft Charging And Arcing By Remote Sensing,
2014
AFRL
Feasibility Of Detecting Spacecraft Charging And Arcing By Remote Sensing, Dale C. Ferguson, Jeremy Murray Krezan, David A. Barton, Jr Dennison, Stephen Gregory
Journal Articles
More than 50 years after the dawn of the space age, most spacecraft still do not have sensors onboard capable of detecting whether they are at potentials likely to put them at risk of severe charging and the concomitant arcing, or, indeed, even capable of detecting when or if they undergo arcing. As a result, anomaly resolution has often been hit or miss, and false diagnoses are probably common. In this paper, a few remote sensing techniques that could be applied for remotely detecting spacecraft charging and/or arcing, and their feasibility, are examined: surface glows from high-energy electron impact, x-rays …
Structural And Electronic Origin Of The Magnetic Structures In Hexagonal Lufeo3,
2014
Temple University
Structural And Electronic Origin Of The Magnetic Structures In Hexagonal Lufeo3, Hongwei Wang, Igor V. Solovyev, Wenbin Wang, Xiao Wang, Philip J. Ryan, David J. Keavney, Jong-Woo Kim, Thomas Z. Ward, Leyi Zhu, Jian Shen, X. M. Cheng, Lixin He, Xiaoshan Xu, Xifan Wu
Xiaoshan Xu Papers
Using combined theoretical and experimental approaches, we studied the structural and electronic origin of the magnetic structure in hexagonal LuFeO3. Besides showing the strong exchange coupling that is consistent with the high magnetic ordering temperature, the previously observed spin reorientation transition is explained by the theoretically calculated magnetic phase diagram. The structural origin of this spin reorientation that is responsible for the appearance of spontaneous magnetization, is identified by theory and verified by x-ray diffraction and absorption experiments.
The Ferroelectricity At The Nanoscale,
2014
Institute of Crystallography, Russian Academy of Sciences, Moscow
The Ferroelectricity At The Nanoscale, Vladimir M. Fridkin, Stephen Ducharme
Stephen Ducharme Publications
The review of ferroelectric properties at the nanoscale is presented. Determining the nanoscale, authors bear in mind the film thickness equal by the order of value to the size of critical domain nucleus. Three phenomena are considered: ferroelectric switching, scaling of coercive field and bulk photovoltaic effect. The investigation of ferroelectricity at the nanoscale started 20 years ago. The nanoscaled ferroelectricics with perovskite structure came to be considered only the last few years.
Nanoscale Thermoelectrics: A Study Of The Absolute Seebeck Coefficient Of Thin Films,
2014
University of Denver
Nanoscale Thermoelectrics: A Study Of The Absolute Seebeck Coefficient Of Thin Films, Sarah J. Mason
Electronic Theses and Dissertations
The worlds demand for energy is ever increasing. Likewise, the environmental impact of climate change due generating that energy through combustion of fossil fuels is increasingly alarming. Due to these factors new sources of renewable energies are constantly being sought out. Thermoelectric devices have the ability to generate clean, renewable, energy out of waste heat. However promising that is, their inefficiency severely inhibits applicability and practical use. The usefulness of a thermoelectric material increases with the dimensionless quantity, ZT, where, Z = S2σ/κ, and S, σ, and κ are the Seebeck coefficient and electrical and thermal …
Ferroelectric Switching In Epitaxial Gete Films,
2014
National Institute of Advanced Industrial Science and Technology (AIST), Japan
Ferroelectric Switching In Epitaxial Gete Films, A. V. Kolobov, D. J. Kim, A. Giussani, P. Fons, J. Tominaga, R. Calarco, Alexei Gruverman
Alexei Gruverman Publications
In this paper, using a resonance-enhanced piezoresponse force microscopy approach supported by density functional theory computer simulations, we have demonstrated the ferroelectric switching in epitaxial GeTe films. It has been shown that in films with thickness on the order of several nanometers reversible reorientation of polarization occurs due to swapping of the shorter and longer Ge-Te bonds in the interior of the material. It is also hinted that for ultra thin films consisting of just several atomic layers weakly bonded to the substrate, ferroelectric switching may proceed through exchange of Ge and Te planes within individual GeTe layers.
Multiferroic Hexagonal Ferrites (H-Rfeo3, R=Y, Dy-Lu): An
Experimental Review,
2014
University of Nebraska-Lincoln
Multiferroic Hexagonal Ferrites (H-Rfeo3, R=Y, Dy-Lu): An Experimental Review, Xiaoshan Xu, Wenbin Wang
Xiaoshan Xu Papers
Hexagonal ferrites (h-RFeO3, R=Y, Dy-Lu) have recently been identified as a new family of multiferroic complex oxides. The coexisting spontaneous electric and magnetic polarizations make h-RFeO3 rare-case ferroelectric ferromagnets at low temperature. Plus the room-temperature mul- tiferroicity and predicted magnetoelectric effect, h-RFeO3 are promising materials for multiferroic applications. Here we review the structural, ferroelectric, magnetic, and magnetoelectric properties of h-RFeO3. The thin film growth is also discussed because it is critical in making high quality single crystalline materials for studying intrinsic properties.
Laboratory Manual For Physics Of Lasers And Modern Optics, 13th Ed,
2014
University of Nebraska - Lincoln
Laboratory Manual For Physics Of Lasers And Modern Optics, 13th Ed, Stephen Ducharme
Stephen Ducharme Publications
You will encounter challenging puzzles and explore new and exciting physical phenomena. You will be provided with sufficient tools, guidance and other resources, but what you learn depends on your inquisitiveness and creativity. This laboratory course is designed to serve two purposes: 1) To explore a variety of physical principles using the fascinating and diverse behavior of light. 2) To learn some of the principles behind the pervasive and expanding area of optical and laser technology. This course is suitable for students of science, life sciences, and engineering, or any student who is curious about light. The prerequisites are the …
