Bulletin of the American Physical Society
APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016; Baltimore, Maryland
Session E21: Experimental Techniques and Results: Static and Dynamic High-Pressure Physics |
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Sponsoring Units: DCMP DCOMP Chair: Audrey Grockowiak, National High Magnetic Field Laboratory Room: 320 |
Tuesday, March 15, 2016 8:00AM - 8:12AM |
E21.00001: High-Pressure Electrical, Raman, and Structural Measurements on Lithium Sulfide Kathryn Ham, Yogesh Vohra, Georgiy Tsoi High-Pressure studies have been conducted on Lithium Sulfide (Li$_{\mathrm{2}}$S) to 55 GPa, with electrical, structural, and Raman measurements. Due to the highly reactive nature of the sample in air, the loading was conducted in a glove bag under an inert Argon atmosphere. Four probe electrical measurements using designer diamond anvils showed characteristic semiconducting behavior in Li$_{\mathrm{2}}$S up to 33GPa from ambient temperature to 10 K. Li$_{\mathrm{2}}$S was compressed to 55GPa and angle dispersive X-Ray data was collected at the Advanced Photon Source, Argonne National Lab, which showed a phase transition from a face centered cubic phase to a primitive orthorhombic phase. Raman data was obtained for Li$_{\mathrm{2}}$S at ambient conditions after decompression from 55 GPa. The Raman Spectrum showed the characteristic peak for Li$_{\mathrm{2}}$S at 372.5 wavenumbers, but had an additional uncharacteristic peak at 327.4 wavenumbers. There is a possibility that the additional uncharacteristic Raman peak is due to the decomposition of Li$_{\mathrm{2}}$S at high pressure. [Preview Abstract] |
Tuesday, March 15, 2016 8:12AM - 8:24AM |
E21.00002: Pressure tuning the lattice and optical response of Ag$_{\mathrm{2}}$S Zhao Zhao, Hua Wei, Wendy Mao Silver chalcogenides Ag$_{\mathrm{2}}$E (E $=$ S, Se, and Te) is a group of materials attracting intense scientific and industrial interest recently. The ability to tune their crystal structure and electronic structure away from their pristine states opens up new optics and opto-electronics applications. In this work, we systematically studied the high pressure structural and optical behavior of Ag$_{\mathrm{2}}$S by in-situ angle dispersive X-ray Diffraction (XRD) and Infrared (IR) measurements in a diamond anvil cell. Though a series of structural transitions and lattice contractions, the structural symmetrization of Ag$_{\mathrm{2}}$S is seen from the decrease of $\beta $from 99$^{\mathrm{o}} $to 90$^{\mathrm{o}}$. The IR transmission and reflection measurements showed that pressure continuously tuned semiconducting Ag$_{\mathrm{2}}$S to metallic at around 22 GPa. By Drude model analysis of the IR reflectivity, the optical conductivity shows radical evolution. In particularly, the highest DC conductivity reaches 100 $\Omega^{\mathrm{-1}}$cm$^{\mathrm{-1\thinspace }}$at 40 GPa . Our results highlight pressure's dramatic role in tuning the lattice and electronic state of silver chalcogenides. [Preview Abstract] |
Tuesday, March 15, 2016 8:24AM - 8:36AM |
E21.00003: Synthesis and Characterization of Bulk BC8 Si Haidong Zhang, Timothy Strobel Silicon, an essential element for modern industry, has several allotropes existing at ambient conditions. Among them, one of the most important phases is the metastable Si-III (BC8) structure. Although it has been known since 1960s, experimental characterization of its properties is still rare primarily due to lack of large bulk samples. Common methods produce BC8 Si samples with the size of micrometers in dimension, preventing definitive experimental measurements. In this work we report synthesis of phase pure bulk BC8 Si with the size of a few millimeters through the multi-anvil press method. The structure was confirmed by powder X-ray diffraction and further supported by the Raman spectrum. Its electrical resistance exhibits clear temperature dependence, increasing from 300 K to 2K. A crossover region occurs around 80 K to 100 K, showing a stronger dependence below 80 K. We also report its optical properties, thermal stability and phonon density of states. [Preview Abstract] |
Tuesday, March 15, 2016 8:36AM - 8:48AM |
E21.00004: Experimental Equation of State of Hafnium Metal to 210 GPa Yogesh Vohra, Jeffrey Montgomery, Spencer Smith, Georgiy Tsoi The equation of state of hafnium metal has been measured using a platinum pressure marker to 210 GPa. Beveled diamonds with 35 micron central flats were used to compress a sample consisting of a mixture of platinum and hafnium that was packed with 6 nm diamond powder. It was hoped that this geometry would provide an alternative method of creating a second-stage pressure region to reach multi-megabar pressures. Powder diffraction patterns were collected across the high-pressure region using an x-ray beam collimated to 1x2 microns in a grid with a spacing of 1 micron. At the highest loads, a pressure gradient of 90 GPa was observed across the sample. This gradient allows for the construction of an equation of state over this range from data collected in only 3 minutes of synchrotron x-ray time. A new analysis program suite employing a measurement of spectral overlap has been developed to identify the multiple structures present, fit lattice parameters, and analyze the newly available gradient information. [Preview Abstract] |
Tuesday, March 15, 2016 8:48AM - 9:00AM |
E21.00005: Molecular crystals as precursors for poly-nitrogen Gustav Borstad, Jennifer Ciezak-Jenkins The application of pressure to matter results in dramatic modifications of its properties. The compression of molecular crystals first eliminates ``empty'' space between the molecules. It then alters the electron density distribution, favoring the increase of atomic coordination and the formation of polymers. The polymerization of low-Z compounds into covalently-bonded networks in three dimensions tend to generate materials characterized by superconductivity, super-hardness, and high-energy density.$^{\mathrm{1}}$ Poly-nitrogen (analogous to diamond) has been synthesized under extreme conditions above 100 GPa and 2000 K in diamond anvil cells, but could not be recovered to ambient conditions.$^{\mathrm{2}}$ A useful form of poly-nitrogen would have to be synthesized at low-pressure with enhanced stability at ambient conditions. The changes in the intermolecular and intramolecular interactions with pressure play a crucial role in the synthesizing and stabilizing of the structure as well as in tuning its properties. In this talk, we provide Raman and x-ray diffraction data on nitrogen-containing compound biuret and compare it to work on other possible poly-nitrogen precursors. References [1] W. Grochala \textit{et al.,} \textit{Angew. Chem. Int. Ed.} \textbf{46, }3620 (2007). [2] M. I. Eremets \textit{et al.}, \textit{Nat. Mater. }\textbf{3,} 558 (2004). [Preview Abstract] |
Tuesday, March 15, 2016 9:00AM - 9:12AM |
E21.00006: High-pressure thermal properties of liquid, crystalline, and amorphous H2O Zachary Geballe, Viktor Struzhkin We have developed a new technique to measure thermal conductivity and heat capacity of any insulator compressed inside a diamond anvil cell. The method uses Joule heating of a platinum foil or thin-film that is pressed against the sample. Electrical current oscillates at frequencies up to 300 kHz and we infer the amplitude of temperature oscillation via a third-harmonic voltage measurement. The melting and freezing of water in a diamond cell, including 30 K hysteresis, is documented with this new technique when temperature is varied over hours. We will also present calorimetry results using cooling timescales from seconds to milliseconds, which may be short enough to pass through "no-man's land" into the stability field of glassy water. [Preview Abstract] |
(Author Not Attending)
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E21.00007: High Pressure XANES studies on Mn dopeHigh Pressure XANES studies on Mn doped Bi2Te3 Brian Light, Ravhi Kumar, Jason Baker, Prabhakaran Dharmalingam, Changyong Park Bi$_{\mathrm{2}}$Te$_{\mathrm{3}}$, Bi$_{\mathrm{2}}$Se$_{\mathrm{3}}$, and Sb$_{\mathrm{2}}$Te$_{\mathrm{3}}$~are narrow band-gap semiconductors have been extensively studied along with their alloys due to their promising technological applications as thermoelectric materials. More recently pressure induced superconductivity and structural transition have been observed in these materials around 7 GPa [1,2]. ~Here we have performed high pressure x-ray near edge spectroscopy (XANES) measurements at Bi L-III edge on Mn (0.1) doped Bi$_{\mathrm{2}}$Te$_{\mathrm{3}}$ samples to understand the variation of the Bi valence across the pressure induced superconductivity regime. We have inferred notable changes in the Bi valence at high pressure conditions. The results will be discussed in detail. Work at the University of Nevada Las Vegas (ALC) is funded by U.S. Department of Energy Award DE-SC0001928. Portions of this work were performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT is supported by DOE-BES, DOE-NNSA, NSF, and the W.M. Keck Foundation. APS is supported by DOE-BES, under Contract No. DE-AC02-06CH1135. [Preview Abstract] |
Tuesday, March 15, 2016 9:24AM - 9:36AM |
E21.00008: Equation of state of palladium hydride and deuteride to 100 GPa Keenan Brownsberger, Muhtar Ahart, Maddury Somayazulu, Stephen Gramsch, Russell Hemley To study the behavior of palladium hydrides under pressure, we loaded palladium foils in hydrogen or deuterium environments in two separate diamond anvil cells. We subsequently measured x-ray diffraction up to 100 GPa at room temperature. No structural phase transition was observed for either PdD$_{\mathrm{x}}$ or PdH$_{\mathrm{x}}$ between 0 GPa and 100 GPa. The pressure-volume data were fitted with the third-order Birch-Murnaghan equation of state, which gave an initial volume of 10.8 cm$^{\mathrm{3}}$/mol, a bulk modulus of 153 GPa, and its derivative of 4.3 for palladium hydride. An initial volume of 10.6 cm$^{\mathrm{3}}$/mol, a bulk modulus of 162 GPa, and its pressure derivative of 4.6 were determined for palladium deuteride. From initial volumes, we conclude that x$=$1 for both PdD$_{\mathrm{x}}$ and PdH$_{\mathrm{x}}$. This work is supported by the Carnegie-DOE Alliance Center. [Preview Abstract] |
Tuesday, March 15, 2016 9:36AM - 9:48AM |
E21.00009: Development of safety containment system for experiments on radioactive and other hazardous materials with large volume Paris-Edinburgh press at APS and first measurements on depleted-uranium Matthew Jacobsen, Nenad Velisavljevic Recent technical developments using the large volume Paris-Edinburgh press platform have enabled x-ray synchrotron studies at high pressure and temperature conditions (Kono, Y. \textit{et al.} \textit{Rev. Sci. Instrum.} \textbf{83,} 033905 (2012)). However, application for hazardous materials requires special handling due to safety issues, reactivity, or other challenges. Facility safety requirements require adequate containment for operation in the variety of environments available. In this talk, we will present a containment setup developed to enable studies of such materials. In particular, studies of the phase diagram of uranium using ultrasonic interferometry to determine the elasticity, mechanical, and thermal properties will be discussed. These results present the first high pressure studies of combined elasticity and thermal properties of depleted uranium metal as well as demonstration of a containment system for making such measurements. [Preview Abstract] |
Tuesday, March 15, 2016 9:48AM - 10:00AM |
E21.00010: NMR in a Diamond Anvil Pressure Cell Matthew Lawson, Adam Dioguardi, Samuel Weir, Blaine Bush, Mihindra Dunuwille, Shanti Deemyad, Nichlas Curro We present recent advances in the use of diamond anvil pressure cells in nuclear magnetic resonance measurements. This technique allows access to new regions of the phase diagrams of iron pnictide and heavy fermion materials, and promises to allow NMR experiments under pressures not previously accessible. [Preview Abstract] |
Tuesday, March 15, 2016 10:00AM - 10:12AM |
E21.00011: Reactive decomposition of low density PMDI foam subject to shock compression Scott Alexander, William Reinhart, Aaron Brundage, David Peterson Low density polymethylene diisocyanate (PMDI) foam with a density of 5.4 pounds per cubic foot (0.087 g/cc) was tested to determine the equation of state properties under shock compression over the pressure range of 0.58 - 3.4 GPa. This pressure range encompasses a region approximately 1.0-1.2 GPa within which the foam undergoes reactive decomposition resulting in significant volume expansion of approximately three times the volume prior to reaction. This volume expansion has a significant effect on the high pressure equation of state. Previous work on similar foam was conducted only up to the region where volume expansion occurs and extrapolation of that data to higher pressure results in a significant error. It is now clear that new models are required to account for the reactive decomposition of this class of foam. The results of plate impact tests will be presented and discussed including details of the unique challenges associated with shock compression of low density foams. [Preview Abstract] |
Tuesday, March 15, 2016 10:12AM - 10:24AM |
E21.00012: Modeling shock-driven reaction in low density PMDI foam Aaron Brundage, C. Scott Alexander, William Reinhart, David Peterson Shock experiments on low density polyurethane foams reveal evidence of reaction at low impact pressures. However, these reaction thresholds are not evident over the low pressures reported for historical Hugoniot data of highly distended polyurethane at densities below 0.1 g/cc. To fill this gap, impact data given in a companion paper for polymethylene diisocyanate (PMDI) foam with a density of 0.087 g/cc were acquired for model validation. An equation of state (EOS) was developed to predict the shock response of these highly distended materials over the full range of impact conditions representing compaction of the inert material, low-pressure decomposition, and compression of the reaction products. A tabular SESAME EOS of the reaction products was generated using the JCZS database in the TIGER equilibrium code. In particular, the Arrhenius Burn EOS, a two-state model which transitions from an unreacted to a reacted state using single step Arrhenius kinetics, as implemented in the shock physics code CTH, was modified to include a statistical distribution of states. Hence, a single EOS is presented that predicts the onset to reaction due to shock loading in PMDI-based polyurethane foams. [Preview Abstract] |
Tuesday, March 15, 2016 10:24AM - 10:36AM |
E21.00013: Static Pressure Above 300 GPa Using Chemical Vapor Deposited Two-stage Diamond Micro-anvils Jeffrey Montgomery, Gopi Samudrala, Georgiy Tsoi, Spencer Smith, Yogesh Vohra Two-stage diamond micro-anvils were grown via chemical vapor deposition (CVD) on beveled diamond anvils with 30 micron central flats. These anvils were used to compress a pre-indented rhenium foil to pressures in excess of 300 Gigapascals (GPa) at relatively small applied loads. Powder diffraction patterns were collected across the high-pressure region using an x-ray beam collimated to 1x2 microns in a grid with a spacing of 1 micron. While multi-megabar pressures were seen across the entire second stage, the highest pressure regions were confined to areas of a few microns in diameter. These were observed at points near the edge of the second stage with nearby pressure gradients as high as 100 GPa/micron. The transmitted x-rays show that the second stage plastically deformed while maintaining multi-megabar pressures. This may have created a second-stage gasket consisting of CVD diamond and rhenium that supported the pressure gradient without substantial external confining pressure. Further improvements in two-stage diamond micro-anvils would require controlling the geometry and microcrystalline/nanocrystalline diamond content during CVD growth process. [Preview Abstract] |
Tuesday, March 15, 2016 10:36AM - 10:48AM |
E21.00014: High-pressure X-ray diffraction, Raman, and computational studies of MgCl$_{2}$ up to 1 Mbar: Extensive pressure stability of the $\beta $-MgCl$_{2}$ layered structure. Elissaios Stavrou, Joseph Zaug, Sorin Bastea, I-Feng Kuo, Jonathan Crowhurst, Bora Kalkan, Martin Kunz, Zuzana Konopkova Magnesium chloride with the rhombohedral layered CdCl$_{2}$-type structure ($\alpha $-MgCl$_{2})$ has been studied using x-ray diffraction and Raman spectroscopy up to 1 Mbar. The results reveal a second-order phase transition to a hexagonal layered CdI$_{2}$-type structure at 0.7 GPa. This phase transition affects the stacking of the Cl anions, resulting to a shorter $c$-axis. An anisotropic compression along $c$-axis was observed during initial compression; altered above 10 GPa due to the repulsion between adjacent Cl-layers. According to previous theoretical studies, a series of phase transitions towards, initially, the 3D rutile (6-fold Mg cations) at 17 GPa and to fluorite structure (8-fold Mg cations) at 70 GPa are proposed. According to our experimental study MgCl$_{2}$ remains in a 2D layered structure up to 1Mbar keeping the 6-fold coordination of Mg cations. This observation contradicts with the general structural behavior of compressed AB$_{2}$ compounds; we conducted \textit{ab-initio} calculations to elucidate the mechanisms that extend the remarkable structural stability of MgCl$_{2}$. [Preview Abstract] |
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