Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session E35: Experiments and Results at High Pressure, Static and Dynamic |
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Sponsoring Units: DCMP DMP Chair: Maddury Somayazulu, Geophysical Laboratory Room: 298 |
Tuesday, March 14, 2017 8:00AM - 8:12AM |
E35.00001: Synthesis of a new vdW compound (Xe)(Cl$_{\mathrm{2}})$ and ionic XeCl$_{\mathrm{2}}$ under pressure Maddury Somayazulu, Changyong Park, Yue Meng, Stephen Gramsch, Russell Hemley A number of xenon compounds have been synthesized at high pressure-high temperature conditions recently. Most of them have been shown to be molecular, van der Waals compounds. Recently, it has been shown that in the case of Xe-O system, pressure induces changes in the xenon valence state thereby confirming the hypothesis that pressur induces hyper-valency in xenon compounds. Indeed, this causes XeF$_{\mathrm{2}}$ to transition to XeF$_{\mathrm{4}}$, XeF$_{\mathrm{6}}$ and ultimately to XeF$_{\mathrm{8}}$. In the Xe-Cl$_{\mathrm{2}}$ system, we observe the formation of a vdW compound that can be transformed to a non-molecular compound at higher pressures and under laser heating. Using a combination of XANES and XRD at 16-BM-D of HPCAT, we have experimental evidence of valence changes that manifest in huge Raman intensities in the vdW compound. [Preview Abstract] |
Tuesday, March 14, 2017 8:12AM - 8:24AM |
E35.00002: High Pressure Low Temperature X-Ray Diffraction Studies of UO2 and UN single crystals. Daniel Antonio, Daniel Mast, Barbara Lavina, Krzysztof Gofryk Uranium dioxide is the most commonly used nuclear fuel material in commercial reactors, while uranium nitride also has many thermal and physical properties that make it attractive for potential use in reactors. Both have a cubic fcc lattice structure at ambient conditions and transition to antiferromagnetic order at low temperature. UO2 is a Mott insulator that orders in a complex non-collinear 3k magnetic structure at about 30 K, while UN has appreciable conductivity and orders in a simpler 1k magnetic structure below 52 K. Both compounds are characterized by strong magneto-structural interactions, understanding of which is vital for modeling their thermo-physical properties. While UO2 and UN have been extensively studied at and above room temperature, little work has been done to directly study the structure of these materials at low temperatures where magnetic interactions are dominant. In the course of our systematic studies on magneto vibrational behavior of UO2 and UN, here we present our recent results of high pressure X-Ray Diffraction (up to 35 GPa) measured below the Neel temperature using synchrotron radiation. [Preview Abstract] |
Tuesday, March 14, 2017 8:24AM - 8:36AM |
E35.00003: High Pressure-High Temperature Phase Diagram of Beryllium Staci Brown, Zsolt Jenei, Hyuncae Cynn, William Evans, Magnus Lipp, Jefferey Montgomery, Bruce Baer A detailed understanding of the phase diagram of beryllium impacts fundamental science and technological applications. Despite a simple atomic structure, theoretical modeling of the phase diagram of beryllium has been extremely challenging and remains an area of active investigation [Benedict, ,PRB 09 and Guo, Comp Mat Sci 14]. Beryllium is important to a range of applications, including structural members, x-ray windows, and nuclear reactors and ICF targets. Extension of the experimental understanding of beryllium will serve to inform and advance theoretical efforts and technological applications. To address these needs, we have extended our previous work [Evans, PRB 05], and performed x-ray diffraction studies of high temperature beryllium. We will describe our measurements of the crystal structure, lattice constants, and phase properties of beryllium at high pressures and temperatures. We will discuss insights into this simple yet challenging system. [Preview Abstract] |
Tuesday, March 14, 2017 8:36AM - 8:48AM |
E35.00004: Transition Metals under Extreme Conditions Studied using Chemical Vapor Deposited Nanocrystalline Diamond Micro-Anvils Yogesh Vohra, Samuel Moore, Georgiy Tsoi, Gopi Samudrala The use of nanocrystalline diamond (NCD) micro balls in diamond anvil cells have generated static pressures close to 1000 GPa (1 TPa) in a two-stage compression. An inherent difficulty with this technique is the precise alignment and placement of these NCD micro balls in a sample assembly in diamond anvil cell devices. We have developed a novel technique where these NCD structures are directly grown on an existing diamond anvil with the precision delivered by the projection lithography. The NCD diamond micro-anvil is grown using a microwave plasma chemical vapor deposition on areas defined by a tungsten mask utilizing mask-less lithography. The NCD structures were grown on a diamond anvil and tested in a two-stage compression in a diamond anvil cell and the pressures were determined using x-ray diffraction at HPCAT beamline 16-ID-B, Advance Photon Source. In a series of experiments, transition metals Tungsten (W) was compressed to 264 GPa, Rhenium (Re) was compressed to 500 GPa, and Osmium (Os) was compressed to 253 GPa. X-ray transmission scans and pressure profile measurements indicate that the NCD anvil can support large pressure gradients and retain their structural integrity to extreme conditions. A further optimization of NCD geometry and diamond grain size can lead to even higher pressures in diamond anvil cell devices. [Preview Abstract] |
Tuesday, March 14, 2017 8:48AM - 9:00AM |
E35.00005: White-Beam X-ray Diffraction and Radiography Studies on High-Boron Containing Borosilicate Glass at High Pressures Kathryn Ham, Yogesh Vohra, Yoshio Kono, Andrew Wereszczak, Parimal Patel Multi-angle energy-dispersive x-ray diffraction studies and white-beam x-ray radiography were conducted with a cylindrically shaped (1 mm diameter and 0.7 mm high) high-boron content borosilicate glass sample (17.6{\%} B2O3) to a pressure of 13.7 GPa using a Paris-Edinburgh (PE) press at Beamline 16-BM-B, HPCAT of the Advanced Photon Source. The measured structure factor S(q) to large q $=$ 19 {\AA}$^{\mathrm{-1}}$, is used to determine information about the internuclear bond distances between various species of atoms within the glass sample. Sample pressure was determined with gold as a pressure standard. The sample height as measured by radiography showed an overall uniaxial compression of 22.5 {\%} at 13.7 GPa with 10.6{\%} permanent compaction after decompression to ambient conditions. The reduced pair distribution function G(r) was extracted and Si-O, O-O, and Si-Si bond distances were measured as a function of pressure. Raman spectroscopy of pressure recovered sample as compared to starting material showed blue-shift and changes in intensity and widths of Raman bands associated with silicate and B3O6 boroxol rings. [Preview Abstract] |
Tuesday, March 14, 2017 9:00AM - 9:12AM |
E35.00006: High Pressure Crystal Structure Refinements and Equation of State of Rare Earth Metal Ytterbium to 226 GPa. Christopher Perreault, Georgiy Tsoi, Kevin Hope, Yogesh Vohra The divalent rare earth metal Ytterbium (Yb) has been studied to a pressure of 226 GPa in a diamond anvil cell utilizing copper as a x-ray pressure standard. High quality image plate x-ray diffraction data was collected at high pressures using HPCAT beamline 16-ID-B at the Advance Photon Source. The crystal structure parameters were determined from the measured x-ray diffraction intensities using the GSAS structural refinement. Yb undergoes a series of transitions from the ambient pressure face centered cubic (fcc) to body centered cubic (bcc) to hexagonal close packed (hcp) to a reentrant fcc phase below 100 GPa. The hexagonal phase with 3 atoms/cell (hP3) is found to be stable between 100 GPa and 200 GPa. We found evidence for yet another structural phase transition at 200 GPa in Yb. The crystal structure parameters for hP3 and the new phase will be presented to 226 GPa. The measured equation of state shows that the rare earth metal Yb is compressed to 25 {\%} of it ambient pressure volume at 226 GPa with implications for its electronic structure under extreme conditions. [Preview Abstract] |
Tuesday, March 14, 2017 9:12AM - 9:24AM |
E35.00007: High Pressure and Temperature Effects in Polymers David Bucknall, Valeria Arrighi, Kim Johnston, Iain Condie Elastomers are widely exploited as the basis for seals in gas and fluid pipelines. The underlying behaviour of these elastomer at the high pressure, elevated temperatures they experience in operation is poorly understood. Consequently, the duty cycle of these materials is often deliberately limited to a few hours, and in order to prevent failure, production is stopped in order to change the seals in critical joints. The result is significant time lost due to bringing down production to change the seals as well as knock on financial costs. In order to address the fundamental nature of the elastomers at their intended operating conditions, we are studying the gas permeation behaviour of hydrogenated natural butyl rubber (HNBR) and fluorinated elastomers (FKM) at a high pressure and elevated temperature. We have developed a pressure system that permits gas permeation studies at gas pressures of up to 5000 psi and operating temperatures up to 150$^{\circ}$ C. In this paper, we will discuss the nature of the permeation behaviour at these extreme operating conditions, and how this relates to the changes in the polymer structure. We will also discuss the use of graphene-polymer thin layer coatings to modify the gas permeation behaviour of the elastomers. [Preview Abstract] |
Tuesday, March 14, 2017 9:24AM - 9:36AM |
E35.00008: Effect of compression rate on ice VI crystal growth using dDAC Yun-Hee Lee, Yong-jae Kim, Sooheyong Lee, Yong Chan Cho, Geun Woo Lee It is well known that static and dynamic pressure give different results in many aspects. Understanding of crystal growth under such different pressure condition is one of the crucial issues for the formation of materials in the earth and planets. To figure out the crystal growth under the different pressure condition, we should control compression rate from static to dynamic pressurization. Here, we use a dynamic diamond anvil cell (dDAC) technique to study the effect of compression rate of ice VI crystal growth. Using dDAC with high speed camera, we monitored growth of a single crystal ice VI. A rounded ice crystal with rough surface was selected in the phase boundary of water and ice VI and then, its repetitive growth and melting has been carried out by dynamic operation of the pressure cell. The roughened crystal showed interesting growth transition with compression rate from three dimensional to two dimensional growth as well as faceting process. We will discuss possible mechanism of the growth change by compression rate with diffusion mechanism of water. [Preview Abstract] |
Tuesday, March 14, 2017 9:36AM - 9:48AM |
E35.00009: Probing Dynamics in Granular Media of Contrasting Geometries via X-Ray Phase Contrast Imaging and PDV Ryan Crum, Darren Pagan, Jon Lind, Michael Homel, Ryan Hurley, Eric Herbold, Minta Akin Granular systems are ubiquitous in our everyday world and play a central role in many dynamic scientific problems including mine blasting, projectile penetration, astrophysical collisions, explosions, and dynamic compaction. An understanding of granular media's behavior under various loading conditions is an ongoing scientific grand challenge. This is partly due to the intricate interplay between material properties, loading conditions, grain geometry, and grain connectivity. Previous dynamic studies in granular media predominantly utilize the macro-scale analyses VISAR or PDV, diagnostics that are not sensitive to the many degrees of freedom and their interactions, focusing instead on their aggregate effect. Results of a macro-scale analysis leave the principal interactions of these degrees of freedom too entangled to elucidate. To isolate the significance of grain geometry, this study probes various geometries of granular media subjected to gas gun generated waves via in-situ X-ray analysis. Analyses include evaluating displacement fields, grain fracture, inter- and intra-granular densification, and wave front motion. Phase Contrast Imaging (PCI) and PDV analyses feed directly into our concurrent meso-scale granular media modeling efforts to enhance our predictive capabilities. [Preview Abstract] |
Tuesday, March 14, 2017 9:48AM - 10:00AM |
E35.00010: Real-time Mesoscale Visualization of Dynamic Damage and Reaction in Energetic Materials under Impact Wayne Chen, Michael Harr, Nicholas Kerschen, Jesus Maris, Zherui Guo, Niranjan Parab, Tao Sun, Kamel Fezzaa, Steven Son Energetic materials may be subjected to impact and vibration loading. Under these dynamic loadings, local stress or strain concentrations may lead to the formation of hot spots and unintended reaction. To visualize the dynamic damage and reaction processes in polymer bonded energetic crystals under dynamic compressive loading, a high speed X-ray phase contrast imaging setup was synchronized with a Kolsky bar and a light gas gun. Controlled compressive loading was applied on PBX specimens with a single or multiple energetic crystal particles and impact-induced damage and reaction processes were captured using the high speed X-ray imaging setup. Impact velocities were systematically varied to explore the critical conditions for reaction. At lower loading rates, ultrasonic exercitations were also applied to progressively damage the crystals, eventually leading to reaction. [Preview Abstract] |
Tuesday, March 14, 2017 10:00AM - 10:12AM |
E35.00011: Shock Compression Spectroscopy of Quantum Dots James Christensen, Alexandr Banishev, Dana Dlott We have investigated CdSe quantum dots (QDs) as photoluminescent probes of shocked solids. They could be especially useful for composite materials, where the individual components could be tagged with different color QDs. The QDs are tiny (4 nm) spherical emitters, pumped by a continuous laser during shock or diamond anvil experiments up to 12 GPa. In the diamond anvil the QDs are hydrostatically compressed and the emission blueshifts with increasing pressure. By contrast, in shock experiments the QDs are embedded in a hard glass or a soft polymer matrix and subjected to uniaxial compression, which should mechanically deform them, and the emission redshifts with increasing pressure. We did hundreds of shock experiments with laser-driven flyer plates, measuring time-resolved intensities, spectral shifts and spectral widths with 1 ns time resolution. We also measured the time-dependent strain of the matrix using a fast optomechanical probe. We showed that the QD redshift can measure the strain in the glass or polymer with 1 ns time resolution. In the hard glass above 4 GPa the QDs behave oddly. When the shock arrives, the QDs redshift as the strain increases, but after about 20 ns, the redshift disappears for about 20 ns and then reappears. We think this redshift blinking behavior is related to the shear transients in the matrix, which suggests we might be able to use QDs to measure uniaxial strain and shear. [Preview Abstract] |
Tuesday, March 14, 2017 10:12AM - 10:24AM |
E35.00012: Low-Velocity Impact Characteristics of Iron and Steel Sarah Thomas, Robert Hixson, Lynn Veeser, Cameron Hawkins Steel samples have been subjected to low-velocity symmetrical impact on the order of 200–360 m/s in order to determine both their spall characteristics and the alpha-phase Hugoniot. In addition, older data, some of which is for pure iron, have been ‘mined’ for this information. We present spall strength and tensile strain rate of our data, as well as other data. We have also studied the Hugoniot for the alpha phase of recently and previously obtained data, and compare them with prior reports of the alpha-phase Hugoniot. A comparison of the Hugoniot elastic limit (HEL) for iron and a number of different types of steel, including 1018, HY100, and A36, is presented. [Preview Abstract] |
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