Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session X23: Materials at Static High PressureLive
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Sponsoring Units: GSCCM Chair: Nathalie Vast, CEA-Saclay |
Friday, March 19, 2021 8:00AM - 8:12AM Live |
X23.00001: High-temperature, high-pressure behavior of lithium fluoride Kanani Lee, Sarah M. Arveson, Markus W Daene, Sebastien Hamel, Yue Meng, Dean Smith, Eric Dutra, Minta C Akin Lithium fluoride (LiF) is used extensively as optical windows in dynamic compression experiments and is also used as pressure media and thermal insulation in diamond-anvil cell (DAC) experiments. In order to better understand this important high-pressure standard and ubiquitous window material, we present a high-temperature equation of state of LiF below its melting curve as measured in a laser-heated DAC. These measurements complement already measured low-T isotherms [e.g., see Myint et al., JCP, 2019 for references] performed with resistively-heated DACs and are used to generate phase-aware, thermally accurate equations of state for LiF. |
Friday, March 19, 2021 8:12AM - 8:24AM Live |
X23.00002: The magnetic, structural, and magnetocaloric properties of Ni2Mn0.75Cu0.25Ga synthesized at high-pressure and high-temperature Tej Poudel Chhetri, Jing-Han Chen, David P Young, Igor Dubenko, NAUSHAD ALI, Shane Stadler High-pressure techniques have been extensively used to explore novel materials with advanced functional properties in the field of materials science for decades. The synthesis of materials under high pressure often results in physical properties not achievable by conventional means. In the present work, polycrystalline Ni2Mn0.75Cu0.25Ga alloys were synthesized at ambient pressure and under high-pressure and high-temperature conditions, and their structural and magnetic properties were investigated. Pressure-induced structural transformation from a monoclinic (14M) to a tetragonal DO22-like crystal structure was observed for the sample synthesized under high-pressure. The magnetic and structural transitions of the alloys formed under high-pressure were found to be coupled in all samples, but their transition temperatures were shifted toward higher temperature by a maximum value of 45 K. A significant expansion of the temperature window where the coupled magnetostructural transition occurs with a reduced maximum magnetic entropy change were observed in high-pressure synthesized samples relative to those synthesized at ambient pressure. |
Friday, March 19, 2021 8:24AM - 8:36AM Live |
X23.00003: Pressure-Induced the Purification of Cs4PbBr6 from CsPbBr3 Impurity Thi Lan Anh Nguyen, Duong Nguyen Minh, Dongzhou Zhang, Lin Wang, Youngjong Kang, Jaeyong Kim Lead halide perovskites have been of great interest due to their promising optoelectronic applications. While solution-based synthetic methods have been well developed, they often form mixtures of perovskites with several different phases, which cannot be easily purified by conventional purification methods. Here we report a high-pressure purification method of Cs4PbBr6 perovskite containing a trace amount of CsPbBr3. The synthesized bulk Cs4PbBr6 perovskites exhibit strong photoluminescence at λpeak = ~ 520 nm because of CsPbBr3 embedded in Cs4PbBr6. Our approach utilized that CsPbBr3 crystals are sensitive to the change of pressure and make distortion of Pb-Br bonds at moderately low pressure, while Cs4PbBr6 crystals are much stable at high-pressure condition. With the application of high pressure (20 GPa), the crystalline CsPbBr3 phase turns amorphous while the crystal structure of Cs4PbBr6 is retained without change. Almost 95% of the CsPbBr3 phase can be removed by one cycle of compression. Cs4PbBr6 which originally shows strong green fluorescence becomes non-fluorescent after one cycle of compression. High-pressure compression can be used to selectively remove CsPbBr3 by pressure-induced amorphization without depreciating the Cs4PbBr6 crystal structure. |
Friday, March 19, 2021 8:36AM - 8:48AM Live |
X23.00004: Ultra-high-pressure behavior of Mg2GeO4: Analogue for phases of deep exoplanet interiors Rajkrishna Dutta, Sally Tracy, Jing Yang, Dean Smith, Yue Meng, Stella Chariton, Vitali B. Prakapenka, Thomas S Duffy Silicon coordination changes in minerals influence their physical properties such as density, viscosity, and elemental affinities. Coordination changes in mantle minerals with pressure are expected to influence the structure and dynamics of planetary interiors. In the Earth, 6-coordinated silicates are believed to be stable throughout the lower mantle. However, there is no experimental evidence for silicon coordination greater than 6 in any high-pressure crystalline silicate. |
Friday, March 19, 2021 8:48AM - 9:00AM Live |
X23.00005: Tuning Octahedral Tilting of Ruddlesden-Popper Chalcogenides via Pressure Shanyuan Niu, Feng Ke, Boyang Zhao, Jayakanth Ravichandran, Yu Lin, Wendy Mao Transition metal perovskite chalcogenides 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 of in Ba3Zr2S7 via coupling of the out-of-phase octahedral tilting around the in-plane direction and the in-phase rotation around the stacking direction. However, experimentally obtained Ba3Zr2S7 crystallizes in a higher symmetry centrosymmetric phase with only one octahedral tilting mode. Pressure offers a unique perspective to drive desired 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 reveal structural transitions of Ba3Zr2S7 under pressure. Efforts towards stabilizing the low-symmetry phases with hybrid improper ferroelectricity will also be discussed. |
Friday, March 19, 2021 9:00AM - 9:12AM Live |
X23.00006: Direct formation of nitrogen-vacancy centers in nitrogen doped diamond along the trajectories of swift heavy ions Thomas Schenkel, Arun Persaud, Edward S Barnard, Christina Trautmann, Marilena Tomut We report depth-resolved photoluminescence measurements of nitrogen-vacancy (NV−) centers formed alongthe tracks of swift heavy ions in type Ib synthetic single crystal diamonds that had been doped with 100 ppm nitrogen during crystal growth. Analysis of the spectra shows that NV−centers are formed in regions where electronic stopping processes dominate and not at the end of the ion range where elastic collisions lead to formation of vacancies. Thermal annealing further increases NV yields afterirradiation with SHI preferentially in regions with high vacancy densities. NV centers formed along the tracksof single swift heavy ions can be isolated with lift-out techniques for explorations of color center qubits inquasi 1D registers with average qubit spacing of a few nm and of order 100 color centers per micron along 10 to 30 micron long percolation chains. |
Friday, March 19, 2021 9:12AM - 9:24AM Live |
X23.00007: Magnetostriction in AlFe2B2 in 25 T DC field near room temperature Shivani Sharma, Alexey E Kovalev, Drew J Rebar, D Mann, V Yannello, Michael Shatruk, Alexey Suslov, Julia H. Smith, Theo Siegrist Using the experimental capability of the novel X-ray diffraction instrument available at the 25 Tesla Florida Split Coil Magnet at the NHMFL, Tallahassee an extensive investigation on the magnetostriction of polycrystalline AlFe2B2 have been performed. The DC magnetization measurements confirm the ferromagnetic transition temperature TC to be 283 K. The magnetostriction was measured near TC, at 250, 290, and 300 K. AlFe2B2 exhibits an anisotropic change in lattice parameters as a function of magnetic field near the TC, and a monotonic variation as a function of applied field has been observed. The c-axis increases significantly while the a- and b-axes decrease with the increasing field in the vicinity of TC, irrespective of the measurement temperature. The volume magnetostriction decreases with decreasing temperature and changes its sign across TC. Density functional theory calculations for the non-polarized and spin-polarized (ferromagnetic) models confirm that the observed changes in lattice parameters due to spin polarization are consistent with the experiment. The relationships for magnetostriction are estimated based on a simplified Landau model that agrees well with the experimental results. |
Friday, March 19, 2021 9:24AM - 9:36AM Live |
X23.00008: Quartz tuning forks as high magnetic field thermometers in liquid 3He. Andrew Woods, Alexander Donald, Lucia Steinke, Mark Meisel Many experiments at the NHMFL High B/T Facility take advantage of the thermal properties of liquid 3He to cool experiments by immersion in the liquid[1], the temperature (T) of which can be measured by a miniature quartz tuning fork[2]. Here, the use of these tuning forks in magnetic fields up to 16 T and for T ≤ 1 mK is reported. A novel thermometer, containing a tuning fork in a small volume of 3He has also been developed, and its thermal response time (50 s) and geometry offers a new path to realizing specific heat and thermal transport measurements in high magnetic fields and ultralow temperatures. |
Friday, March 19, 2021 9:36AM - 9:48AM Live |
X23.00009: New Structural Systematics in the Lanthanide Elements at High Pressure Malcolm McMahon, Sarah Finnegan, Edward Pace, Christian Storm, Michael Stevenson, Simon MacLeod, Evgeny Plekhanov, Nicola Bonini, Cedric Weber The pressure-induced phase transitions in the lanthanide elements provide insight into their electronic structures at high densities. After a series of transitions via close-packed structures, the regular trivalent lanthanides undergo first-order transitions to so-called "collapsed" phases, the structures of which are reported as monoclinic. However, the diffraction data from these phases are not well fitted by the monoclinic structure, and the patterns from Nd and Sm are different to those from the higher-Z lanthanides. Here we present diffraction studies on Sm, Nd, Tb, and Y, which reveal that there are two collapsed structures, neither of which is monoclinic. We also show that these new structures are strikingly similar to those observed in the higher-Z actinides at high pressure, greatly strengthening the structural systematics of the 4f and 5f elements. |
Friday, March 19, 2021 9:48AM - 10:00AM Not Participating |
X23.00010: A new pulse-magnetic field diamond anvil cell Daniel Jackson 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. |
Friday, March 19, 2021 10:00AM - 10:12AM Live |
X23.00011: Anderson-Mott Transition in Elemental Tellurium under pressure jaime ferreira de oliveira, Magda B. Fontes, Marcos Moutinho, Marcelo barbosa da silva neto, Stephen Rowley, Elisa Baggio Saitovitch, Carsten Enderlein Elemental tellurium is a small band-gap which is always p-doped. Under hydrostatic pressure, the band gap narrows, and it has been suggested that below its crystal phase transition at 40 kbar, the gap might close, leading to a transition to a non-trivial state. We show that a high quality elemental tellurium single crystal undergoes a quantum phase transitions at low temperature from an Anderson insulator to a disordered metal around 17 kbar. The critical exponents are consistent with a scenario in which the often-discussed pressure induced Lifshitz transition shifts the Fermi level to a position below the mobility edge. Previous experiments with different results can be linked and explained with the possibility of an Anderson-Mott ground state and the observed quantum phase transition at 17 kbar. |
Friday, March 19, 2021 10:12AM - 10:24AM Live |
X23.00012: Preserving a robust CsPbI3 perovskite phase via pressure-directed octahedral tilt Feng Ke, Chenxu Wang, Chunjing Jia, Nathan R. Wolf, Jiejuan Yan, Shanyuan Niu, Thomas Devereaux, Hemamala Karunadasa, Wendy Mao, Yu Lin Functional CsPbI3 perovskite phases are not stable at ambient conditions and spontaneously convert to a non-perovskite δ phase, limiting their applications as solar cell materials. We demonstrate the preservation of a black CsPbI3 perovskite structure to room temperature by subjecting the δ phase to pressures of 0.1 – 0.6 GPa followed by heating and rapid cooling. Synchrotron X-ray diffraction and Raman spectroscopy indicate that this perovskite phase is consistent with orthorhombic γ-CsPbI3. Once formed, γ-CsPbI3 could be then retained after releasing pressure to ambient conditions and shows substantial stability at 35% relative humidity. First-principles density functional theory calculations indicate that compression directs the out-of-phase and in-phase tilt between the [PbI6]4- octahedra which in turn tune the energy differences between δ- and γ-CsPbI3, leading to the preservation of γ-CsPbI3. Our study presents a new strategy for manipulating the (meta)stability of halide perovskites for the synthesis of desirable phases with enhanced materials functionality. |
Friday, March 19, 2021 10:24AM - 10:36AM Live |
X23.00013: Skyrmion host GaV4S8 under high pressure Yuejian Wang, Saqib Rahman, Elaine Sun, Christopher Knill, Dongzhou Zhang, Lin Wang, Vladimir Tsurkan, István Kézsmárki
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Friday, March 19, 2021 10:36AM - 10:48AM Live |
X23.00014: Shear Strength of Superhard Transition Metal Borides under High Pressures Kaleb Burrage, Changyong Park, Yogesh Kumar Vohra Adding lightweight covalently bonded boron atoms interstitially into lattices of high electron density transition metals (Re, Os) results in a unique class of materials with distinct mechanical properties and resistance to thermal degradation at high temperatures. These Transition Metal Borides boast high bulk modulus comparable to diamond (335-395 GPa) and a hardness value of 25-35 GPa. In this study, we have performed high pressure radial x-ray diffraction measurements on OsB2, Os2B3, and ReB2 to provide unique insight into the shear strength and elastic properties under non-hydrostatic compression. The radial x-ray diffraction data to pressure up to 76 GPa has been combined with the density functional theory calculations of shear modulus to obtain the variation of shear strength of transition metal borides as a function of pressure. |
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