Bulletin of the American Physical Society
Joint Fall 2013 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS
Volume 58, Number 10
Thursday–Saturday, October 10–12, 2013; Brownsville, Texas
Session C1: Condensed Matter and Materials Research |
Hide Abstracts |
Chair: Heather Galloway, Texas State University at San Marcos Room: EDBC 1.502 |
Friday, October 11, 2013 2:00PM - 2:12PM |
C1.00001: Ion Beam Irradiation Experiment to Simulate Fast Neutron Damage in Nickel Exposed to Molten Salt Elizabeth Sooby, Magda Caro, Robert Houlton, Feng Lu, Peter McIntyre, Akhdiyor Sattarov, Joseph Tesmer, Yongqiang Wang A novel technology for Accelerator-based Destruction of Actinides in Molten salt (ADAM) is being developed as a method to destroy the transuranics in used nuclear fuel. The core structural components are exposed to radiation damage by fast-spectrum neutrons and corrosion in $\sim$600 C chloride molten fuel salt. Candidate materials for the core vessel and structural components are Ni and Ni-based alloys. An to expose candidate materials to simultaneous molten salt corrosion and ion-beam damage are staged at the Ion Beam Materials Laboratory at Los Alamos National Laboratory. A thin Ni window is engineered to allow the 5.5 MeV proton beam to pass through the window and deposit approximately 20 DPA at the molten salt interfacing surface. CeCl$_{3}$-NaCl is employed as a surrogate for the actinide chloride salt. Irradiation occurs over one week, allowing 100 hours of molten salt exposure. The experimental design and preliminary modeling will be presented here. [Preview Abstract] |
Friday, October 11, 2013 2:12PM - 2:24PM |
C1.00002: Accurate quantum states for a 2D-dipole Daniel Vrinceanu Edge dislocations are crucial in understanding both mechanical and electrical transport in solid and are modeled as linear distributions of dipole moments. The calculation of the electronic spectrum for the two dimensional dipole, represented by the potential energy $V(r,\theta) = p \cos(\theta)/r$ has been the topic of several studies that show significant difficulties in obtaining accurate results. In this work we show that the source of these difficulties is a logarithmic contribution to the behavior of the wave function at the origin, that was neglected by previous authors. By taking into account this non-analytic deviation of the solution of Schr\"odinger's equation superior results, with the expected rate of convergence, are obtained. This goal is accomplished by ``adapting" general algorithms for solving partial derivative differential equations to include the desired asymptotic behavior. We demonstrate this principle for the variational principle and finite difference methods. [Preview Abstract] |
Friday, October 11, 2013 2:24PM - 2:36PM |
C1.00003: Capacitive sensor setup for Creep rate measurement on hydroxide-catalysis bonded silica ears Karla Ramirez, Moises Castillo, Adan Anchondo, Gianpietro Cagnoli, Mario Diaz Analysis of the GEO600 detector data has not shown any evidence of the existence of creep caused by hydroxide catalysis bonds in the mirror suspensions above the measurement sensitivity. Measuring directly the bond creep noise on samples of advanced detectors such as aLigo is a prudent research step. A system for direct detection of creep at a higher sensitivity is being design and mounted close to a set of aLIGO prototype test masses. Such system is based on capacitive sensors, which are used to measure any displacement either linear or rotational. This capacitive sensors are based on the electrical capacitance dependence of a conductor due to the distance from a dielectric body. A set of thermistors able to measure changes in temperature also form part of this setup. The goal is to be able to prove the presence of creep on the bonding used in the aLigo suspension test masses, and if such creep noise is presented find what produce it. [Preview Abstract] |
Friday, October 11, 2013 2:36PM - 2:48PM |
C1.00004: Experimental evidence for the trapping of low energy positrons at the surfaces of a topological insulator K. Shastry, P.V. Joglekar, N.G. Fazleev, A.H. Weiss We present evidence for the presence of a positron surface state on the surface of a topological insulator. Results from a series of experiments performed at university of Texas at Arlington on a Bi$_{\mathrm{2}}$Te$_{\mathrm{2}}$Se sample. A magnetically guided beam of positrons was used to deposit positrons at the sample surface. Peaks in the energy spectrum of electrons emitted as a result of positron annihilation were observed at 23 eV, 55 eV, 99 eV and 283 eV which we attribute to the Bi, Se, Te, and C Auger transitions resulting from surface state positrons annihilating with the O$_{\mathrm{5}}$ 5d$_{\mathrm{5/2}}$ O$_{\mathrm{4}}$ 5d$_{\mathrm{3/2}}$, M$_{\mathrm{4}}$ 3d$_{\mathrm{3/2\thinspace }}$(M$_{\mathrm{5}}$ 3d$_{\mathrm{5/2}})$, M$_{\mathrm{4}}$ 3d$_{\mathrm{3/2\thinspace }}$(M$_{\mathrm{5}}$ 3d$_{\mathrm{5/2}})_{\mathrm{\thinspace }}$and K 1s core levels respectively. The existence of these peaks points to the fact that a significant fraction of positrons annihilate at or very close to the surface (we note that if positrons were annihilating uniformly throughout the bulk, the Auger signal would not be seen due to the attenuation of electrons leaving from the bulk. This is evidence for the existence of a surface state). Our results are consistent theoretical calculations by Saniz et al that have shown that such a surface state should exist. [Preview Abstract] |
Friday, October 11, 2013 2:48PM - 3:00PM |
C1.00005: Positron Doppler Broadening Study of Clays and Shale Samples Fnu Ameena, Hayden Morgan, C.A. Quarles A previous detailed positron spectroscopy study of well-characterized reservoir rocks (carbonates and sandstones) has demonstrated the usefulness of positron Doppler Broadening spectroscopy in characterizing rocks [1]. The commonly measured S and W parameter were shown to be reproducible bulk properties of the rocks. A follow-up study has been undertaken to investigate clay and shale samples. While clay and shale are more complex and more heterogeneous than the reservoir rocks, it is believed that positron lifetime and Doppler broadening spectroscopy can help to characterize and distinguish the various samples and perhaps provide new useful insights into these materials. An overview of the Doppler broadening spectroscopy results will be presented and discussed for five well defined clay standards, (Na and Ca Montmorilinite, Smectite and Kaolin) and a variety of shale samples, which typically consist of mixtures of carbonate, silica and clay as well as organic carbon. The results include the usual S and W parameters as well as momentum distribution ratios of samples to standards such as Si and SiO2. \\[4pt] [1] J.M. Urban-Klaehn and C. A. Quarles, Journal of Applied Physics 86 (1999)355. [Preview Abstract] |
Friday, October 11, 2013 3:00PM - 3:12PM |
C1.00006: Effect of morphology on exchange bias in NiCoMnSn and NiCoMnIn magnetic shape memory alloys Pavel Lapa, James A. Monroe, Brian E. Franco, Ibrahim Karaman, Igor V. Roshchin Exchange bias (EB) which manifests itself as a shift of hysteresis loop is one of puzzling magnetic properties of magnetic shape memory (MSM) alloys. Despite a few attempts to explain the mechanism, there is no comprehensive model describing it. The main obstacle is a lack of information about the magnetic structures in martensitic and austenite phases. In contrast to classical EB systems where the exchange coupling happens at the interface between ferromagnetic and antiferromagnetic layers, the EB coupling in MSM alloys occurs due to coexistence of ferromagnetic and antiferromagnetic regions in bulk martensitic state. The purpose of our work is to obtain the information about the size distribution of ferromagnetic and antiferromagnetic regions. We observe a correlation of EB with the secondary heat treatment for NiCoMnIn alloys. Comparative first order reversal curve (FORC) analysis for NiCoMnSn samples with different heat treatments suggests a correlation between morphology and distribution of exchange bias values. To enhance the difference in morphology, we developed a fabrication procedure for a set of NiMnSn samples with varied alloy composition. We report the results of structural analysis obtained using wavelength-dispersive X-ray spectroscopy (WDS) and magnetic characterization of these samples. Work is funded by TAMU and US NSF-DMR MMN program/MWN initiative grant 1108396. [Preview Abstract] |
Friday, October 11, 2013 3:12PM - 3:24PM |
C1.00007: Overview of thermoelectric materials and their emerging applications Camas Key, Karen Martirosyan Waste heat derived from any heat generating process: radioisotope decay, fuel combustion, solar thermal energy, geothermal energy, waste incineration, nuclear reactor cooling, industrial manufacturing, etc.; can be converted into electricity through the application of thermoelectric materials. The optimal thermoelectric materials exhibit high electronic conductivity in addition to very low thermal conductivity, two physical properties that are often hard to decouple within a material system. Narrow gap semiconductors prove to be the most suitable thermoelectric materials. Thermoelectric performance depends greatly upon phonon scattering over a wide range of phonon modes, analogous to having structures that scatter phonons on many different length scales. The ability to control material structures on the nanoscale helps in this regard and has been shown to reduce thermal conductivity without degrading electrical properties. Here we review characteristics shared by the best thermoelectric materials and focus on new material synthesis approaches to achieve greater thermoelectric performance. [Preview Abstract] |
Friday, October 11, 2013 3:24PM - 3:36PM |
C1.00008: Removing contribution of the inelastically scattered valence band electrons from Ag(100) Auger Photoelectron Coincidence Spectrum Prasad Joglekar, K Shastry, Steven Hulbert, Alex Weiss Ag(100) spectrum is obtained using Auger Photoelectron Coincidence Spectroscopic(APECS) technique. In the spectrum the 4p NVV auger peak is accompanied by high intensity at the low energies referred as the low energy tail (LET). A LET has contributions arising from intrinsic as well as extrinsic to the Auger transition. The LET's extrinsic contribution is comprised largely of secondary electron background which includes inelastically scattered photoelectrons, valence band electrons and photo excited valence band electron. The inelastically scattered valence band electrons lose energy due to inelastic scattering and end up in the lower energy part of the spectrum We did a series of APECS measurements to estimate the contribution from the inelastically scattered valence band electron. This contribution was subtracted from the Ag (100) APECS spectrum to obtain a spectrum free of inelastic scattered valance band. Our measurement was the first of its kind and the only one to attempt to remove all the secondary electron background. [Preview Abstract] |
Friday, October 11, 2013 3:36PM - 3:48PM |
C1.00009: Heat treatment of Textured Powder Bi-2212/Ag Wire Feng Lu, Kyle Damborsky, Peter McIntyre Bi-2212/Ag conductors are being considered for future very high field magnet technology, beyond the 20 T limit of Nb3Sn magnet technology. long-length Bi-2212/Ag conductor and coils still yield engineering current density (Je) much less than expected. The main current limit mechanism is residual bubbles in fully-processed wires due to porosity of the as-drawn wire and porosity agglomeration during the melting process. We have demonstrated that the high core density of textured powder (TPC) filaments minimizes the porosity of as-drawn wires. We are investigating three heat treatments to achieve high Je by reducing the bubble size and density in fully processed conductors: Over-Pressure Sintering (OPS), Over-Pressure Melting (OPM), and Current Control Melting (CCM). [Preview Abstract] |
Friday, October 11, 2013 3:48PM - 4:00PM |
C1.00010: Charge-transfer with CVD graphene: Recent Progress Les Sheffield, Igor Lyuksyutov, Dudley Herschbach, Daya Rathnayaka The unique electronic, mechanical, and optical properties of graphene, a one atom thick layer of carbon atoms, were reported in 2004 (Science 22 October 2004: 306 (5696)). One obvious property is the large surface area (2630 m$^2$/g) which indicates that every atom of the sample is capable of adsorbing gas molecules -- thus providing the largest sensing area per volume. Utilizing this advantage to fabricate gas sensors requires considerable knowledge into the charge transfer effects exhibited by graphene samples with different types and quantities of surface dopants. Resistivity measurements with gate bias on commercially produced, chemical vapor deposited (CVD) graphene samples with large area are not feasible so far due to leakage through the insulating layer. Starting with 1cmX1cm commercially produced CVD graphene sheets we have prepared samples with mm dimensions for electronic transport measurements with gate biasing. Measurements can be made in a temperature range of 100-400K in high vacuum with the exposure of the sample to different gas beams (Rev. Sci. Instrum. 83, 064102) after degassing at 150$^{\circ}$C. Preliminary results of our experiment will be presented. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700