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 V23: Materials in Extremes: Static CompressionFocus Live
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Sponsoring Units: GSCCM Chair: Maxim Bykov, Howard University |
Thursday, March 18, 2021 3:00PM - 3:12PM Live |
V23.00001: Pressure-induced amorphization and existence of molecular and polymeric amorphous forms in dense SO2 Huichao Zhang, Ondrej Toth, Xiao-Di Liu, Roberto Bini, Eugene Gregoryanz, Philip Dalladay-Simpson, Simone De Panfilis, Mario Santoro, Federico Aiace Gorelli, Roman Martonak We report here the pressure-induced amorphization and reversible structural transformation between two amorphous forms of SO2: molecular amorphous and polymeric amorphous, with the transition found at 26 GPa over a broad temperature regime, 77 K to 300 K. The transformation was observed by both Raman spectroscopy and X-ray diffraction in a diamond anvil cell. The results were corroborated by ab initio MD simulations, where both forward and reverse transitions were detected, allowing a detailed analysis of the respective local structures. The high-pressure polymeric amorphous form was found to consist mainly of disordered polymeric chains made of 3-coordinated sulfur atoms connected via oxygen atoms, with few residual intact molecules. Our study provides an example of polyamorphism in a system consisting of simple molecules with multiple bonds [1]. |
Thursday, March 18, 2021 3:12PM - 3:24PM Live |
V23.00002: Electronic correlations and transport in iron at Earth’s core conditions Leonid V. Pourovskii, Jernej Mravlje, Monica Pozzo, Dario Alfe The transport properties of iron under Earth’s inner core conditions are essential input for the geophysical modelling but are poorly constrained experimentally. Here we show that the thermal and electrical conductivity of iron at those conditions remains high even if the electron-electron-scattering (EES) is properly taken into account. This result is obtained by ab initio simulations taking into account consistently both thermal disorder and electronic correlations. Thermal disorder suppresses the non-Fermi-liquid behaviour of the body-centred cubic (bcc) iron phase, hence, reducing the EES; the total calculated thermal conductivity of this phase is 220 Wm-1K-1 with the EES reduction not exceeding 20%. The EES and electron-lattice scattering are intertwined and cannot be treated separately. The total conductivity thus exhibits a markedly weaker dependence on the EES as compared with predictions of the Matthiessen’s rule. In the hexagonal close-packed iron the EES is also not increased by thermal disorder and remains weak; the calculated total thermal conductivity, 214 Wm-1K-1, is very close to that in bcc-Fe. Our main finding thus holds for the both likely iron phases in the inner core. |
Thursday, March 18, 2021 3:24PM - 3:36PM Live |
V23.00003: Energy Gap Closure of Crystalline Molecular Hydrogen with Pressure Vitaly Gorelov, Markus Holzmann, David M Ceperley, CARLO PIERLEONI We study the gap closure with pressure in Phases III and IV of molecular crystalline hydrogen by Quantum Monte Carlo methods [1]. Nuclear quantum and thermal effects are considered from first principles with Coupled Electron Ion Monte Carlo. The fundamental electronic gaps are obtained from grand-canonical Quantum Monte Carlo methods [2] properly extended to quantum crystals. Nuclear zero point effects cause a large reduction in the gap (~2eV ). As a consequence the fundamental gap closes at 530GPa for ideal crystals while at 360GPa for quantum crystals. Since the direct gap remains open until ~450GPa, the emerging scenario is that upon increasing pressure in phase III (C2/c-24 crystal symmetry) the fundamental (indirect)gap closes and the system enters into a bad metal phase where the density of states at the Fermi level increases with pressure up to ~450GPa when the direct gap closes. Our work partially supports the interpretation of recent experiments in high pressure hydrogen. |
Thursday, March 18, 2021 3:36PM - 3:48PM Live |
V23.00004: Emergence of order from disorder in amorphous silica under extreme deformation Md Hossain The mechanical behavior of glass has been a subject of active research for many decades. Yet the underlying mechanisms that govern crack nucleation and propagation in amorphous silica remains less understood. In this talk, we will present an atomistic scale understanding of the relative roles of Si and O atoms in governing the crack nucleation and propagation criteria at finite temperatures. Our results suggest that both crack nucleation and propagation are governed by chainlike nanoscale virial stress-fibers that form as a collection of regularly spaced atoms. They belong to a set of interacting tetrahedral structures comprising Si and O atoms, and they form and break continuously during the crack nucleation and propagation process. Additionally, the virial stress fields in the domain exhibit a highly heterogeneous and species-dependent structure at low deformation. However, with increased deformation, a set of ordered structure emerges prior to undergoing failure. This transition from disorder to order forms the physical foundation for complex deformation and fracture behavior of amorphous silica. The details of the atomistic process regulating the underlying mechanisms are undetectable from the macroscopic stress-strain data. |
Thursday, March 18, 2021 3:48PM - 4:00PM Live |
V23.00005: Strength, deformation, and equation of state of tungsten carbide to 66 GPa Benjamin Brugman, Feng Lin, Mingda Lv, Curtis Kenney-Benson, Dmitry Popov, Lowell Miyagi, Susannah Dorfman Hard ceramics like tungsten carbide exhibit remarkable physical properties such as wear-resistance, ultra-incompressibility, and high yield stress, yet the quasi-static yield strength and deformation of WC have not been studied at high pressure. Its equation of state is also debated, with a reported bulk modulus from 329 to 452 GPa and pressure derivative from 1.25 to 5.45. We compressed bulk and nano-crystalline WC to 66 GPa in the diamond anvil cell with synchrotron X-ray diffraction at the Advanced Photon Source Sector 16. In quasi-hydrostatic Ne medium, nano WC is slightly more compressible than bulk WC, with respective bulk moduli of K0 = 377 ± 7 and 397 ± 7 GPa and pressure derivatives K0’ = 3.8 ± 0.3 and 3.3 ± 0.3. Strength and plasticity were determined by Rietveld refinement of lattice strain and texture. Slip mechanisms were determined by Elasto-viscoplastic self-consistent simulations of strain and texture. Preferred orientation occurs at ~30 GPa, with WC sustaining differential stress of ~12-15 GPa. Above yielding, WC has similar strength to other hard materials. Deformation is accommodated by prismatic slip on {10-10}<-12-10> and {10-10}<0001>, with pyramidal slip on {10-10}<-2113> activated at ~40-50 GPa. These mechanisms differ from basal slip in W and hcp metals. |
Thursday, March 18, 2021 4:00PM - 4:12PM Live |
V23.00006: First-principles predictions of electrical and thermal conductivity of platinum and iridium at high pressure conditions Kai Luo, Jan Minar, Ronald Cohen Platinum-group metals, such as iridium (Ir) are important elements for their unique high density, high melting temperature, and high corrosion resistance. Platinum (Pt) has a high stability solid-phase over a range of pressure and temperature and is often used as a pressure standard. We investigate the fundamental properties, thermal and electrical conductivities of Ir and Pt at high pressure and temperature conditions using the first-principles methods. We compare experimental data with results from two theoretical approaches in the framework of Kubo-Greenwood theory. The scattering mechanism is simulated by (1) coherent potential approximation via Debye model, and (2) first-principles molecular dynamics. The study provides electrical and thermal conductivity at high (P, T) conditions and discusses the violation of the Wiedemann-Franz law. |
Thursday, March 18, 2021 4:12PM - 4:24PM Live |
V23.00007: Anomalous Electronic Switching Behavior in Compressed La2S3 Hiranya Pasan Vindana Wadhurawa Mudiyanselage, Arnab Majumdar, Elliot Snider, Nathan Dasenbrock-Gammon, Raymond McBride, Rajeev Ahuja, Ranga P Dias Insulator-to-metal transitions (IMT) are a hallmark of many families of quantum materials. Impulsively induced electronic phases are typically short-lived, with lifetimes on the order of the electromagnetic pulse width or the energy relaxation time of the material. Yet, in quantum materials with wrinkled free-energy landscapes, impulsive stimulation can trap the system in new metastable states and 'hidden' phases not apparent in common phase diagrams of quantum materials. Lanthanide sesquisulfides (Ln2S3) manifest unusual magnetic and electronic behavior. However, very few studies on Lanthanide sesquisulfides have been reported under pressure. In an effort to expand the understanding of La2S3, we performed Raman and resistance measurements up to 20 GPa. At low pressures between 16-18 GPa an interesting softening of the low frequency modes in the Raman was accompanied with laser driven resistance change, which provide an exciting opportunity to tune their exotic properties by impulsive stimulation harvesting metastable hidden phases of these materials. |
Thursday, March 18, 2021 4:24PM - 4:36PM Live |
V23.00008: Nature of high-pressure electride phases and their possible detection with x-ray diffraction Rafi Ullah, Stanimir Bonev The direct experimental detection of high pressure electride phases of matter is a challenging problem. It was suggested that the interstitial localization of valence electrons - a signature of the electride phase - could be detected using x-ray diffraction experiments. Using first-principles calculations we have studied the change in the features of underlying physical quantities such as electronic charge density. We have obtained structure factor from the high pressure electronic charge density to quantify detectable changes in the x-ray scattering pattern. We have also compared the electron localisation function and the first principles charge density to corroborate the nature and extent of interstitial electron localisation. |
Thursday, March 18, 2021 4:36PM - 5:12PM Live |
V23.00009: Experimental observations on microstructure of iron and other metals at high pressures and temperatures Invited Speaker: Rostislav Hrubiak Materials subjected to high pressure (P) and high/low temperature (T) treatments in the diamond anvil cell (DAC) often exhibit complexity and inhomogeneity, on length scales ranging from nanometers to tens of microns. A recently developed ability to perform detailed spatially resolved characterizations of the inhomogeneity under high P, or in the high P-T treated samples, has allowed to unlock some of the complexity and to gain an understanding of several of emerging physical phenomena in high pressure sciences. |
Thursday, March 18, 2021 5:12PM - 5:24PM Live |
V23.00010: Water-Gas Shift Reaction in Deep Earth Nore Stolte, Junting Yu, Zixin Chen, Ding Pan The deep carbon cycle plays a critical role in the sustainable development of life. The change in the oxygen fugacity in Earth’s interior leads to stabilization of carbon with different oxidation states, from diamond and methane in the deep Earth to CO2 and carbonate minerals near Earth’s surface. In the industrial water-gas shift reaction, CO is oxidized to CO2 in the presence of water, during which formic acid is considered a short-lived intermediate. Using extensive ab initio molecular dynamics simulations, we found that at the high pressure (P) and high temperature (T) conditions as found in the deep Earth, CO reacts with water to generate formic acid as a product. We also calculated the free energy of formic acid, and predicted the possible P-T range of the existence of formic acid when carbon is not fully oxidized. Our findings have important implications for the formation of diamonds and hydrocarbon reactions inside Earth. |
Thursday, March 18, 2021 5:24PM - 5:36PM On Demand |
V23.00011: Modulating electronic properties of semiconductor materials at large mechanical deformation Zhe Shi, Evgenii Tsymbalov, Ming Dao, Subra Suresh, Alexander Shapeev, Ju Li Elastic strain engineering explores the full 6D space of admissible ultra-large strains and the effects on physical properties. However, the complexity of controllably engineering materials properties by mechanical forces necessitates first-principles computations to design an optimal straining pathway. In our work, to map the 6D strain space, we developed a general machine learning framework that adopts convolutional neural networks, physics informed data representation scheme, and a new active learning algorithm to allow bandgap and band structure prediction, band extrema detection, and effective mass calculations for semiconductor materials. Combining this method with experimentally validated finite-element simulations, we identified the most energy-efficient strain pathways that would reversibly transform an ultrawide-bandgap material to a metalized state without phonon stability. The fast and reliable inference of the proposed model opens a path towards analyzing and scrutinizing general band structures in the vast 6D strain space. |
Thursday, March 18, 2021 5:36PM - 5:48PM On Demand |
V23.00012: Insight into Structural Variations in CaSiO3 Glass under High-Pressure. Young Jay Ryu, Tony Yu, Clemens Prescher, Stella Chariton, Eran Greenberg, Vitali B. Prakapenka, Sergey N. Tkachev, Peter Eng, Joanne Stubbs, Przemyslaw Dera, Heather Watson, Mark L. Rivers, Yanbin Wang Pressure-induced structural modifications in silicate melts play a crucial role in controlling dynamic processes in the Earth's deep interiors and other terrestrial planets. In order to understand the origin and significance of deep melt in Earth’s interiors, it is important to obtain laboratory constraints on thermodynamics and physical properties at high-pressure and high-temperature. However, despite their crucial roles in dynamic processes, little is known about the structures of liquid silicates throughout the Earth’s pressure regime because the high-pressure and high-temperature environments entail severe experimental difficulties. Therefore, there were still many issues that needed to be addressed in the study of silicate melts. Here, we investigate CaSiO3 glass up to ~70 GPa in the diamond anvil cell by using a combination of experimental techniques, including Raman spectroscopy, X-ray scattering, and Brillouin spectroscopy. The detailed structural and property data collected on the CaSiO3 glass allow us to gain first-hand information on how structural changes affect physical properties and uncover missing links between the structure and physical property relationship for silicate melts and glasses. |
Thursday, March 18, 2021 5:48PM - 6:00PM Not Participating |
V23.00013: Discovery of RSAVS superconductors Liling Sun, Cheng Huang, Jing Guo, Kai Liu, Hongming Weng, Zhongyi Lu, Qi Wu, Tao Xiang, Robert Cava The transition temperature (TC) between normal and superconducting states usually exhibits a dramatic increase or decrease with increasing applied pressure. Here we present, in contrast, a new kind of superconductor that exhibits the exotic feature that TC is robust against large volume shrinkages induced by applied pressure (here naming them as “RSAVS superconductors”). This RSAVS behavior, which has never been predicted or proposed as a new kind of superconductors previously, occurs universally in a certain kind of superconductors with body centered cubic lattice. Our electronic structure calculations indicate that in the RSAVS state the contribution of the degenerate dx2-y2 and dz2 orbital electrons remains almost unchanged at the Fermi level, suggesting that these are the electrons that may play a crucial role in stabilizing the TC in the RSAVS state. We preliminarily analyzed the reasonability and validity of this suggestion by the Homes’ law. |
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