Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session Y18: Materials at Extreme Conditions: Static High-Pressure |
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Sponsoring Units: GSCCM DMP DCOMP Chair: Yuejian Wang, Oakland University Room: LACC 306B |
Friday, March 9, 2018 11:15AM - 11:27AM |
Y18.00001: Effects of Simultaneous Pressure and Temperature on the Stability of Si24 and ZrO2 Brent Fultz, Peter Ahnn, Timothy Strobel Using diamond anvil cells with temperature control, we measured Raman spectra on materials at elevated temperatures and pressures. The shifts of individual Raman peaks, Δω, were fit to functions of the form |
Friday, March 9, 2018 11:27AM - 11:39AM |
Y18.00002: Dense B-N Compounds: Synthesis Conditions and Physical Properties Serge Desgreniers, Spencer Sterling The hexagonal form of boron nitride, isostructural to graphite, transforms to a three-dimensional network with the wurtzite structure upon the application of high pressure at room temperature. In its wurtzite phase, boron nitride exhibits a very low compressibility. Upon decompression, the wurtzite phase can be partially retrieved. In the study we have measured the physical properties wurtzitic boron nitride and the fraction of high-density phase retrievable from the initial bulk and nanoscale hexagonal boron nitride, as obtained from compression under various hydrostatic conditions and high temperature. The interaction and bonding formation at high density between boron nitride and different pressure transmitting media leading to the possibility of formation of dense intercalated compounds is also examined. |
Friday, March 9, 2018 11:39AM - 11:51AM |
Y18.00003: Grain boundary effect on the compressibility of diamond and a possible transition in diamond grain boundary Jiuhua Chen, Lingyun Tang, Ruilian Tang, Dawei Fan, Bin Yang, Wenge Yang Equation of state of diamond powder with different average grain sizes was investigated using in situ synchrotron x-ray diffraction. Comparison of compression curves was made for two samples with average grain size of 50nm and 100nm. Experiments were conducted at room temperature and high pressures up to 50 GPa. Fitting the compression data in the full pressure range into the third order Birch-Murnaghan equation of state yields bulk modulus (K) and its pressure derivative (K’) of 392 GPa and 5.3 for 50nm sample and 398GPa and 4.5 for 100nm sample respectively. Using a simplified core-shell grain model, this result indicates that the grain boundary has an effective bulk modulus of 54 GPa. This value is similar to that observed for carbon nanotube validating the recent theoretical diamond surface modeling. Differential analysis of the compression cures demonstrates clear relative compressibility change at the pressure about 20 GPa. When fit the compression data below and above this pressure separately, the effect of grain size on bulk modulus reverses in the pressure range above 20 GPa. This observation indicates a possible transition of grain boundary structure, likely from sp2 hybridization at the surface towards sp3 like orbital structure which behaves alike the inner crystal. |
Friday, March 9, 2018 11:51AM - 12:03PM |
Y18.00004: Optically Detected Magnetic Resonance of Nitrogen Vacancies in a Diamond Anvil Cell Using Designer Diamond Anvils Louis Steele, Matthew Lawson, Michael Onyszczak, Blaine Bush, Ziwen Mei, Adam Dioguardi, Jonathan King, Anna Parker, Alexander Pines, Samuel Weir, William Evans, Kenneth Visbeck, Yogesh Vohra, Nicholas Curro Optically detected magnetic resonance of nitrogen vacancy centers in diamond offers novel routes to both DC and AC magnetometry in diamond anvil cells under high pressures (>3GPa). However, a serious challenge to realizing experiments has been the insertion of microwave radiation into the sample space without screening by the gasket material. We utilize designer anvils with lithographically-deposited metallic microchannels on the diamond culet as a microwave antenna. We present optically-detected magnetic resonance (ODMR) data in a diamond anvil cell up to 8 GPa, using designer anvils to insert low power microwaves into the sample space. This work is the first use of designer anvils at microwave frequencies, and thus enables us to perform ODMR without the difficulties of inserting a conducting channel either into the sample space between the anvil and the gasket, or surrounding the anvil with a coil and using high power microwaves. |
Friday, March 9, 2018 12:03PM - 12:15PM |
Y18.00005: Pressure Induced Structural Changes in Cesium Fluoride: Theory and Experiment Eunja Kim, Daniel Sneed, Philippe Weck, Michael Pravica We have investigated pressure induced structural changes in cesium fluoride using density functional theory and synchrotron X-ray diffraction (XRD) measurements. The calculated total energy and enthalpy clearly indicate that the B1 → B2 transition occurs near 5 GPa, which is confirmed by our high pressure synchrotron XRD study of cesium fluoride (CsF), up to 120 GPa. It is found that no phase transitions were observed between 5 -120 GPa experimentally in this study. Unit cell data were determined from the known B2 (CsCl) structure for all of the pressures studied above 5 GPa, and an equation of state (EOS) was fit to the data using a 3rd order Birch–Murnaghan equation in this phase. The Density Functional Theory (DFT) calculations were also carried out to compute an EOS and bulk modulus. Our experimental results agreed very well with the predicted bulk modulus and EOS data from DFT. |
Friday, March 9, 2018 12:15PM - 12:27PM |
Y18.00006: Qubit synthesis under extreme conditions Thomas Schenkel, Qing Ji, Sven Steinke, Peter Seidl, Jaehong Park, Wim Leemans, John Barnard, Leonard Feldman, Norman Tolk, Ryan Thorpe, Andrey Baydin, Halina Krzyzanowska, Stepan Bulanov, Jianhui Bin Spins of electrons and nuclei and color centers are promising qubits for large scale integration. The reliable formation of such qubits has remained a significant challenge [1]. We recently showed that NV-centers can be formed locally by electronic excitation of the diamond matrix without thermal annealing [2]. We now report on studies of qubit formation using intense ion pulses. We used analytical modeling and simulations (HYDRA) of rapid local electronic excitation and heating of materials followed by rapid quenching to stabilize the phases that were induced during a pulse [3]. Ion pulses are generated by laser-plasma acceleration at the BELLA petawatt laser facility at LBNL [4] and can excite materials into extreme temperature-pressure regimes. The 1 Hz repetition rate of BELLA enables the exploration of quantum materials in new regimes. We discuss prospects for qubit synthesis and strategies for the discovery of novel color center qubit candidates. |
Friday, March 9, 2018 12:27PM - 12:39PM |
Y18.00007: Controlled High Pressure High Temperature Phase Diagram Scanning with Self-Heating Diamonds Jeffrey Montgomery Further advances have been made in the control systems for self-heating diamond anvils, which incorporate laser-etched heating circuits on a pair of metal-sputtered diamond anvils to create a doublesided heating setup. This allows for rapid (100 K/s) heating and cooling rates, with precision limited by measurement rate. Thermally insulating alumina seats and water cooling prevent thermal expansion in the cell body and allow for continuous measurement without realignment of the sample. This system is also portable, allowing it to be incorporated in diffraction measurements at synchrotron. |
Friday, March 9, 2018 12:39PM - 12:51PM |
Y18.00008: A Combined Theoretical and Experimental Study of the Pressure-induced Phase Transitions in GeSe Hulei YU, Dexiang Gao, Xiancheng Wang, Xueyan Du, Xiaohuan Lin, Wenhan Guo, Ruqiang Zou, Kuo Li, Yue Chen A recent study revealed that GeSe transforms into a new β phase under a hydrostatic pressure of 6 GPa [J. Am. Chem. Soc., 2017, 139 (7), pp 2771–2777]. In this work, we systematically investigate the pressure-induced phase transitions of GeSe up to 16 GPa by first-principles evolutionary structure searches. Two novel intermediate phases are found to exist at a pressure range in-between those of the existing α and β phases. We find that α-GeSe transforms into a rhombohedral phase with a space group of R3m (a GeTe prototype) at a small hydrostatic pressure. Laser-heated diamond anvil cell experiments were performed to provide further evidence of the existence of this R3m phase, which shows robust ferroelectricity in analogous to GeTe. By further increasing the external pressure, the R3m phase gradually transforms into a rock-salt phase. Based on electronic structure calculations from density functional theory and a tight-binding model, we show that this rock-salt phase is a topological crystalline insulator. The new phases presented in this work greatly enrich our knowledge of the high-pressure behaviors of GeSe. |
Friday, March 9, 2018 12:51PM - 1:03PM |
Y18.00009: Reversible Crystallization in Amorphous As2Se3 under Pressure Azkar Saeed Ahmad In pressure-induced reversible structural transitions, the term ‘reversible’ refers to the recovery of the virgin structure in a material upon complete decompression. Pressure-induced amorphous-to-crystalline transitions have been claimed to be reversible, but evidence of the fact that amorphous material recovers its virgin amorphous structure upon complete depressurization has been lacking. In amorphous As2Se3 (a-As2Se3) chalcogenide, however, we report a novel reversible amorphous-to-crystalline transition providing compelling experimental evidence that upon complete decompression the recovered amorphous phase is structurally the same to that of the virgin (as-cast) amorphous phase. Combining the experimental results with ab initio molecular dynamics simulations, we elucidate that the amorphization is mediated by a surplus of total free energy in the high pressure face-centered cubic phase as compared to the virgin amorphous phase, and the structural recovery to the virgin amorphous phase is a consequence of an enhancement in covalent bonding character over interlayer forces upon complete decompression. Furthermore, we also observed a 2-dimensional-to-3-dimensional network transition under compression, and its reversibility upon decompression. |
Friday, March 9, 2018 1:03PM - 1:15PM |
Y18.00010: Pressure-Induced Structural and Electronic Topological Transitions in Bi1.5Sb0.5Te1.8Se1.2 Alloy Joonseok Kim, Rinkle Juneja, Nilesh Salke, Witold Palosz, Venkataraman Swaminathan, Sudhir Trivedi, Abhishek Singh, Deji Akinwande, Jung-Fu Lin Topological insulators (TIs) have surface states that are topologically protected against scattering or defects, and thus have been the subject of intense research. Among the A2B3 metal chalcogenide TIs, Bi1.5Sb0.5Te1.8Se1.2 quaternary alloy has been reported to have lowest bulk conductivity, being an optimal composition to study the surface transport properties. Here, using combined theoretical and experimental investigations, we show the hydrostatic pressure effects on the structural, vibrational and topological properties of the Bi1.5Sb0.5Te1.8Se1.2. Within pressure range up to 45 GPa, two structural phase transitions were observed; from R-3m phase to C2/m phase at ~13 GPa, and to disordered I4/mmm phase at ~22 GPa. Within the R-3m phase, several electronic transitions were also observed. Indirect bulk band gap transited to direct bulk band gap at ~5.8 GPa, and bulk gap closed with an appearance of Dirac semimetal (DSM) state at ~8.2 GPa. Anomaly in Full Width at Half Maximum (FWHM) of in-plane Raman peaks and c/a lattice constant ratio suggests contribution of electron-phonon coupling to the DSM transition. |
Friday, March 9, 2018 1:15PM - 1:27PM |
Y18.00011: Pressure Dependent Structural Phase Transition in VO2 Raktima Basu, V. Srihari, Sandip Dhara VO2 is well known for its reversible first order metal to insulator transition (MIT) along with a structural phase transition (SPT) between low-temperature monoclinic, M1 to high-temperature rutile tetragonal, R phase at 340K. Besides M1, another two low temperature phases of monoclinic M2 and triclinic T also evolve during the phase transition. It is argued that MIT is driven by strong electronic correlation compatible with Mott mechanism, resolving a long-standing “chicken-and-egg” debate in VO2. Insulating phase of VO2 can be considered as a collection of 1-D half-filled band, which undergoes first order Mott transition to 1-D infinitely long Heisenberg spin ½ chains leading to structural distortion due to spin-phonon coupling. |
Friday, March 9, 2018 1:27PM - 1:39PM |
Y18.00012: High pressure single crystal diffraction of UO2 and UN Daniel Antonio, Keshav Shrestha, Barbara Lavina, Krzysztof Gofryk Uranium dioxide is an important material which is the primary fuel used in comercial nuclear reactors. and uranium nitride has similar properties that make it a candidate as a possible new fuel material. Both have antiferromagnetic magnetic transitions at low temperatures that corespond to unusual physical behavior, indicating strong magneto-elastic coupling. Below 30.8 K, UO2 shows a small volume collapse due to a latice distortion, as well as rarely seen piezomagnetic behavior. Below 50 K, UN also orders antiferromagnetically and switchs to negative thermal expantion. UN crystalizes in the cubic rocksalt structure, but ongoing magnetostriction measurements show signs of distotions below TN. Using High quality and unifrm single crystals of UO2 and UN, we have systematically examined the crystal structure and change in compressability to high pressures above and below the magnetic transiton temperatures. |
Friday, March 9, 2018 1:39PM - 1:51PM |
Y18.00013: Intermediate valence behavior in YbNi(Ga,In)4 Zachary Brubaker, Ryan Stillwell, Paul Chow, Yuming Xiao, Curtis Kenney-Benson, Rich Ferry, Zsolt Jenei, Scott Donald, Art Nelson, Kevin Huang, Ryan Baumbach, Rena Zieve, Jason Jeffries Strongly correlated rare-earth materials have been heavily studied because of their rich magnetic behavior which can be tuned via the application of pressure. Intermediate valence compounds are particularly interesting, since pressure can favor either a non-magnetic state, as in Ce-compounds, or a magnetic state, as observed in Yb-compounds. Because the rare-earth valence plays such a crucial role in determining magnetic properties, it is imperative to understand both the underlying physics and how to tailor materials to exhibit the desired valence configuration. With this goal in mind, we have performed a comprehensive structural and valence study of the YbNi(Ga,In)4 system. We have measured the pressure dependence of the Yb-valence up to 42 GPa in YbNiGa4 and up to 27 GPa in YbNiIn4 via x-ray absorption spectroscopy (XAS) and resonant x-ray emission spectroscopy (RXES). Additionally, we have performed x-ray diffraction studies on YbNiGa4 and YbNiIn4 in excess of P = 40 GPa. We successfully tuned the Yb-valence from n = 2.15 in YbNiIn4 to n = 2.6 at P = 42 GPa in YbNiGa4. |
Friday, March 9, 2018 1:51PM - 2:03PM |
Y18.00014: Energy-dispersive X-ray diffraction and white-beam radiography on bulk metallic glass, Zr58.5Cu15.6Ni12.8Al10.3Nb2.8 to 5.03 GPa and 800 °C. Kathryn Ham, Yogesh Vohra, Yoshio Kono, Andrew Wereszczak
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Friday, March 9, 2018 2:03PM - 2:15PM |
Y18.00015: Evolution of Electronic and Magnetic Properties of Nominal Magnetite (Fe3O4) Nanoparticles Under Pressure-An XMCD Study Kalpani Werellapatha, Carlos A. Escanhoela, Jr, Daniel Haskel Nanoparticles(NPs) are being extensively studied due to differences in atomic, electronic, magnetic, physical and chemical properties compared to their bulk. As the particle dimensions approach the nanoscale, a large fraction of atoms will be near the surface, resulting in changes in behavior compared to larger particles. Studies of NPs at extreme conditions have seen further modifications of these properties. Magnetite (Fe3O4) is a naturally occurring mineral and have particles in the nano-sized region. We investigate the evolution of electronic and magnetic properties of 6 nm nominal magnetite (Fe3O4) NPs under pressure. Similar investigations on bulk magnetite have been conducted previously, however, only a little is known regarding NPs. Well characterized NPs were prepared using chemical coprecipitation method. We used x-ray magnetic circular dichroism (XMCD) and x-ray absorption spectroscopy (XAS) at Fe K-absorption edge, to investigate electronic and magnetic properties of NPs under pressure, at the Advanced Photon Source, Argonne National Laboratory. The results of this investigation will be presented. |
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