Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session P02: Static High Pressure Experiments |
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Sponsoring Units: GSCCM Chair: James Walsh, Univ of Mass - Amherst Room: 105 |
Wednesday, March 4, 2020 2:30PM - 2:42PM |
P02.00001: Pressure-temperature-magnetic field phase diagram of the molecule-based multiferroic (CH3)2NH2]Mn(HCOO)3 Amanda Clune, Nathan Harms, Kenneth R O'Neal, Kevin Arthur Smith, Kendall Hughey, Dimuthu Obeysekera, Junjie Yang, John Haddock, Naresh S Dalal, Zhenxian Liu, Janice Lynn Musfeldt We employ high pressure susceptibility and vibration spectroscopy to reveal the properties of (CH3)2NH2]Mn(HCOO)3. Combining with prior high field work, we unveil the P-T-H phase diagram of this molecule-based multiferroic. Specifically, we focus on the behavior of the formate bending mode across the order-disorder temperature to expose the role of the formate ligand in the framework stability and symmetry. |
Wednesday, March 4, 2020 2:42PM - 2:54PM |
P02.00002: A new pulse-magnetic field diamond anvil cell Daniel Jackson, Mun K. Chan Measurements in extreme conditions provide valuable insight into material properties.Combining high magnetic field, high pressure, and cryogenics allows for smooth tuning of parameters in a 3-dimensional phase space.The highest magnetic fields are generated using pulse-field magnets and provide more than twice the maximum field compared to direct-current magnets, 100 T vs 45 T. However, pulse fields invariably generate eddy currents in any conductive parts. A diamond anvil cell (DAC) was designed with slits to reduce eddy current loop area. The DAC was machined out of titanium, a poor thermal conductor, and was machined using a tabletop 5-axis CNC. I will present preliminary results from measurements in pulse field at high pressure, and details of the design of the cell. |
Wednesday, March 4, 2020 2:54PM - 3:06PM |
P02.00003: The Role of Hydrogen Bonding in Aromatic Molecular Crystals at High Pressures Hannah Shelton, Przemyslaw Dera, Sergey Tkachev, Tommy Yong Noncovalent interactions wield remarkable control in molecular crystals, which can alter properties such as impact sensitivity and chemical reactivity. The presence of hydrogen bonding has been shown to stabilize organic molecular crystals against pressure-dependent polymorphism and amorphization. These effects can be seen in melamine (C3H6N6; 1,3,5-triazine-2,4,6-triamine) and resorcinol (C6H6O2; 1,3-dihydroxybenzene), which are used industrially to produce laminates, adhesives, and flame retardants. Melamine is chemically and structurally similar to many energetic materials, including TATB and RDX. In the crystalline state melamine forms corrugated sheets of individual molecules linked by extensive intra- and inter-plane N-H hydrogen bonds. In comparison, resorcinol has less hydrogen bonding ability as only two hydroxyl groups form intermolecular links. At high pressure, melamine experiences a symmetry change from monoclinic to triclinic above approximately 36 GPa in helium. Conversely, resorcinol remains crystalline to only approximately 6 GPa. Examining the high-pressure intermolecular interactions in these compounds may allow their improved utilization as chemical feedstocks and analogues for related energetic compounds. |
Wednesday, March 4, 2020 3:06PM - 3:18PM |
P02.00004: Tuning Octahedral Tilting of Ruddlesden-Popper Chalcogenide via Pressure Shanyuan Niu, Feng Ke, Boyang Zhao, Jayakanth Ravichandran, Yu Lin, Wendy Mao Transition metal perovskite chalcogenides (TMPCs) are currently of substantial interest as a class of emerging semiconductors for optoelectronic and photonic applications. Ruddlesden-Popper (RP) phases of perovskite chalcogenides have been predicted to be promising candidates to achieve ferroelectric semiconductors with static polar order. Hybrid improper ferroelectricity can be realized in such n=2 RP compounds with a−a−c+ tilt system as Ba3Zr2S7 via coupling of out-of-phase octahedral tilting around in-plane directions and in-phase rotation mode around the stacking direction. However, experimentally obtained Ba3Zr2S7 is in a higher symmetry centrosymmetric phase with only one octahedral tilting mode. Pressure offers a unique perspective to drive such octahedral tilting and study the phase transitions. We report the high-pressure study of Ba3Zr2S7 up to 50 GPa using diamond anvil cells. In-situ Raman spectroscopy and X-ray diffraction analysis are carried out to probe the structural changes. Structural transitions of Ba3Zr2S7 under pressure have been observed. Efforts in stabilizing the low-symmetry phases with hybrid improper ferroelectricity will also be discussed. |
Wednesday, March 4, 2020 3:18PM - 3:30PM |
P02.00005: High Hydrostatic Pressure (0.5–2.5 GPa) Synthesis and
Properties of Bulk “nnx” Rare-Earth Nickel Oxides (RnNinOx)* Sara J Irvine, Gregorio Ponti, Quinn D. B. Timmers, Zachary P. Kuklinski, John Markert We have undertaken rare-earth and alkaline-earth substitutions in known nickel oxide phases, and a search for new such phases, using a hot press. We prepared starting materials both by ambient solid-state reaction (650°C–975°C) and by using high-oxygen-pressure (150–200 bar), high-temperature (T ≈ 1000°C) syntheses, producing either nominal-composition mixed-phase RNiOx materials, or the nearly-simple-perovskite RNiO3 phases, respectively. We then subjected such parent materials [R = Pr, Nd, (La,Y)], as well as hole- and electron-doped varieties, to high quasi-hydrostatic pressures using a hot piston-cylinder apparatus (5–25 kbar, i.e., 0.5–2.5 GPa) at high temperatures (950°C–1050°C). The technique1 can include oxidizers (KClO4), or can be naturally reducing, the latter augmentable by hydrogen. We report product phases; initial syntheses have provided specimens with decreases in undesired starting phases. Our study of other nickelate phases, e.g., R3Ni3O7 and infinite-layer RNiO2, with this technique is ongoing, exploring both steric effects and hole- (Sr2+) and electron-doping (Ce4+) in targeted RnNinOx structures. |
Wednesday, March 4, 2020 3:30PM - 3:42PM |
P02.00006: Superconductivity of platinum hydride PtH Takahiro Matsuoka, Masahiro Hishida, Keiji Kuno, Naohisa Hirao, Yasuo Ohishi, Shigeo Sasaki, Kazushi Takahama, Katsuya Shimizu Pt has a strong electron-phonon (e-p) coupling [1]. On the other hand, the 5d conduction electrons show strong spin fluctuations on the short length and time scales, which suppress the superconductivity. In PtH, hybridization between Pt 5d and H 1s [2] and the resulting strengthened e-p coupling and Tc above 10 K have been predicted [2-5]. We report the ac magnetic susceptibility, electrical resistance, and x-ray diffraction measurements of PtH in diamond anvil cells. At 30 GPa, when PtH is in a P63/mmc structure, PtH exhibits the superconducting transition at 7 K. The observed Tc is higher than that of powdered Pt by more than three orders of magnitude. It is suggested that the noble metal hydrides possibly have higher Tc than elements. |
Wednesday, March 4, 2020 3:42PM - 3:54PM |
P02.00007: O-1earthquake-like precursors: a MaxEnt-μSR MgO study Carolus Boekema, Carlos Morante, Mina Tavakolzadeh, Friedemann T Freund Earthquake-like precursor O-1 effects [1,2] are studied by analyzing Muon-Spin-Resonance (μSR) MgO data using Maximum Entropy (ME). [3,4] MgO is ideal due to its presence in the Earth's crust: O-1or positive-hole formation results from a 2-stage break-up of an O anion pair under high-T or high-P conditions. [2] As T increases above room temperature (RT) a small O-ion % is predicted to produce an O-1state.[2] ME analysis of transverse field (TF; 100 Oe) μSR data of a 3N-MgO single crystal show above RT a Gaussian signal at 1.36 MHz and a Lorentzian signal at 1.4 MHz. For similar oxides like MnO, TFμSR show only the μO Gaussian signal, as positive muons probe near negative O ions. [3,4] The extra 1.4-MHz MgO signal indicates the existence of extended O 2p states. [1, 2] Between 200 & 400 °C where O-1 formation occurs, we find evidence of a missing (3rd μSR) fraction. The relation of O-valency effects and earthquake-like precursors is discussed. 1] FT Freund, Nat Hazards Earth Sys Sci 7(2007) 1. 2] FT Freund et al, Phys Chem Earth 31(2006) 389. 3] C Boekema and MC Browne, MaxEnt 2008, AIP Conf Proc #1073 p260. 4] S Lee et al, HUIC Educ, Math & Eng Tech Conf, Uo HI (2013). |
Wednesday, March 4, 2020 3:54PM - 4:06PM |
P02.00008: Relaxation, Viscosity and Density Scaling of the Hydrogen-bonded System Glycerol at Pressures above 5 GPa William Oliver, Kevin W Lyon Using Tg(P) data for glycerol up to very high pressures of 6.7 GPa, we reanalyze viscosity and relaxation data taken by several groups over different temperature and pressure ranges, constraining these earlier data with our isochronous Tg(P) curve. This analysis allows new insights into the pressure dependence of fragility in such glass forming systems over pressure ranges in which the hydrogen bonded network is broken up. Attempts at thermodynamic scaling are also discussed for glycerol over this large pressure range. |
Wednesday, March 4, 2020 4:06PM - 4:18PM |
P02.00009: Observation of nine-fold coordinated amorphous TiO2 at high pressures Yu Shu, Yoshio Kono, Guoyin Shen, Yanbin Wang, Rostislav Hrubiak Understanding pressure-induced structural changes in amorphous dioxides (a-AO2) is of great importance in many fields of science. Here we report new experimental results of high pressure polyamorphism in amorphous TiO2 (a-TiO2) with the Ti-O coordination number (CN) close to 9. Our experimental data show that CN increases from 7.2 at 15.7 GPa, to 8.8 at 70.2 GPa, and finally reaches a plateau ~8.9 at pressures up to 85.7 GPa. We find that CN of both crystalline TiO2 and a-TiO2 follows a similar and systematic dependence on the ratio (γ) of the ionic radii of Ti and O. The γ of a-TiO2 is 0.614 at 15.7 GPa, which is similar to that of baddeleyite-type TiO2 (~0.61), and increases continuously with pressure. At 70.2 GPa, γ of a-TiO2 is 0.701, which is similar to that of cotunnite-type TiO2 (~0.693). It appears that the CN≈9 plateau of a-TiO2 correlates to the cotunnite-type and Fe2P-type polymorphs, which have the same CN=9 but correspond to different γ values. This CN-γ relationship is applicable to other a-AO2 of a-SiO2 and a-GeO2. All three compounds show surprisingly consistent between CN and γ, implying a unified relation between CN and γ in a-AO2. The established CN-γ relationship may be used to predict the compression behavior of a-AO2 compounds to extreme conditions. |
Wednesday, March 4, 2020 4:18PM - 4:30PM |
P02.00010: Enhancing broadband emission in indirect bandgap lead halide perovskites by hydrostatic pressure SHENYU DAI, Zhaojun Qin, Viktor G. Hadjiev, Chong Wang, Zhiming M. Wang, Guoying Feng, Jiming Bao Although broadband emission caused by self-trapped excitons (STE) has been widely studied in direct bandgap perovskites, few attention has been paid to indirect bandgap perovskites. Here we report that indirect bandgap all-inorganic perovskite exhibits typical STE induced broadband emission. We use diamond anvil cell to study the response of optical properties of 2D perovskite microplates to hydrostatic pressure. The broadband emission intensity increases significantly with increasing pressure, and the peak position is largely blue-shifted by 650 meV. The mechanism of these phenomena is discussed using experimental methods and theoretical calculations. This work shows a potential method to control and utilize indirect bandgap perovskites materials in optoelectronic devices. <div id="gtx-trans" style="position: absolute; left: 169px; top: 60.04px;"> <div class="gtx-trans-icon"> </div> </div> |
Wednesday, March 4, 2020 4:30PM - 4:42PM |
P02.00011: Molecular-Like Equilibrium Behavior of Anatase Nanoparticles in Compressed Hydrothermal Conditions Hengzhong Zhang, Jinyuan Yan, Martin Kunz, Bin Chen, Jillian F. Banfield Nanocrystals are intermediate in size between molecules and micron-scale crystallites. They usually exhibit size-dependent properties and behaviors that are closer to the latter than the former. However, in this work, we found that small titania nanoparticles present molecular-like phase equilibrium behavior under compressed hydrothermal conditions, as evidenced by the fact that both the phase contents and particle sizes of involved titania nanoparticles can increase or decrease in response to altered temperature and/or pressure applied to shift a phase equilibrium. Thermodynamic analysis showed that the phase content of a solid nanophase contributes to the free energy change of the phase equilibrium, in contrast to the textbook knowledge that the thermodynamic activity of a pure solid phase equals one and as such the phase content of a pure solid phase makes no contribution to the equilibrium. This result suggests that much more frequent and stronger collisions among nanoparticles at high-T&P conditions can enhance the energy transfer among individual nanoparticles in a fluid, making them behave collectively more like solute molecules in a solution. This finding renews our understanding of the physical-chemical properties of nanoparticles with strong interparticle interactions. |
Wednesday, March 4, 2020 4:42PM - 4:54PM |
P02.00012: Study on refractive index, EOS and polarizability of atomic, molecular and mixted gases at high pressures up to 60 MPa Chengjun Li The refractive index of initially transparent gases at high pressures is very important for shock velocity measurements in shock compression experiment since the measured shock velocity has to be modified by the refractivity of the initial smaple. In this work, bu using optical frequency domain interferometer (OFDI), we measured the refractive index of atomic (He, Ne, Ar, Kr, Xe), molecular (H2, D2, O2, N2, CO, CH4) and mixed gases (H2-D2, H2+Ar, D2+He, He-Ar, He-Xe) up to 60 MPa. The EOS of part of above gases were measured experimentally, while others were calculated. The polarizability of different gases were derived from their refractive index and density according to Lorentz-Lorenz formula. The mixing rule below 60 MPa were verified by the experimental results of mixed gases investigated in this work. |
Wednesday, March 4, 2020 4:54PM - 5:06PM |
P02.00013: Quasi One-Dimensional Compound and Superconductivity Induced by Pressure Jinlong Zhu, Jun Zhang, Xiancheng Wang, Changqing Jin Ba3TiTe5 was synthesized at HP/HT with infinite face-sharing octahedral TiTe6 chains and Te chains along the c axis, exhibiting a strong 1D characteristic structure. The calculations confirmed the 1D conductor charaterization, and can be considered a starting point to explore the exotic physics induced by pressure to move the 1D conductor to a high-dimensional metal. High-pressure techniques were employed to study the emerging physics dependent on interchain hopping, such as the Umklapp scattering effect, spin/charge density wave, superconductivity and non-Fermi liquid behavior. Finally, a complete phase diagram was plotted. The superconductivity emerges at 9GPa, near which the Umklapp gap is mostly suppressed. Tc is enhanced and reaches a maximum of 6K at 37 GPa, where the SDW or CDW is completely suppressed, and a non-Fermi liquid behavior appears. Our results suggest that the appearance of superconductivity is associated with the fluctuation due to the suppression of the Umklapp gap and that the enhancement of the Tc is related to the fluctuation of the SDW or CDW. |
Wednesday, March 4, 2020 5:06PM - 5:18PM |
P02.00014: Non-uniform thermal gradient evolution in thermally cycled ytterbium silicate-silicon environmental barrier coatings David Olson, Jeroen Deijkers, Kathleen Quiambao, John T Gaskins, Elizabeth Opila, Haydn N G Wadley, Patrick Hopkins The primary purpose of barrier coating materials is to protect underlying media from harsh temperatures and/or environmental conditions that pose to undermine the performance of a system. Thus, materials with high thermomechanical stability and low thermal conductivity are choice candidates as thermal/environmental barrier coating top coats. Systems that implement a ytterbium-disilicate have shown to be promising candidates for next generation gas turbine engines. However, a robust examination of the microscale structural and thermal effects has yet to be performed over a range of cycling conditions. Considering the multi-phase, anisotropic constituents of such systems, a robust understanding of these mechanisms is necessary. In this work, we examine the microstructural and thermal evolution in ytterbium silicate-silicon environmental barrier coatings. The coating system cannot be defined by a single thermal conductivity, as local variations in thermal conductivity arise due to these multi-phase, anisotropic systems. Understanding the evolution and distribution of the thermal gradients associated with high-temperature steam-cycling is necessary for the continued development of these materials as hot-section components in gas-turbine engines. |
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