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 J23: Materials in Extremes: Carbon and Related MaterialsLive
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Sponsoring Units: GSCCM Chair: Rebecca Lindsey, Lawrence Livermore Natl Lab |
Tuesday, March 16, 2021 3:00PM - 3:12PM Live |
J23.00001: Atomistic Evidence of Carbon Allotropes Recovered from High-pressure and High-Temperatures Jianguo Wen, Duan Luo, Srilok Srinivasan, Subramanian Sankaranarayanan It is of importance to form new carbon allotropes as well as understand the transformation mechanism from graphite to diamond. Extensive theoretical studies have been carried out including the prediction of several tens of new forms of carbon allotropes using machine learning, and the understanding of the direct graphite to diamond nucleation mechanism using quality neural-network potential. Here we bridge the gap between the simulation predictions and experimental observations using aberration corrected TEM. First, we report the observation of hexagonal and cubic diamonds with a diaphite structure, which has both diamond-like and graphite-like bond lengths. We will also show atomic observations of the direct transformation pathway from graphite to diamond through an intermediate metastable graphite phase. Overall, the creation of the new carbon forms clues that under modulated high pressure and temperature conditions, the great diversity of carbon covalent bonds could be assembled into carbon allotropes. |
Tuesday, March 16, 2021 3:12PM - 3:24PM Live |
J23.00002: Facile diamond synthesis from lower diamondoids Sulgiye Park, Iwnetim I Abate, Jin Liu, Chenxu Wang, Jeremy Dahl, Robert Carlson, Liuxiang Yang, Vitali B. Prakapenka, Eran Greenberg, Thomas Devereaux, Chunjing Jia, Rodney Ewing, Wendy Mao, Yu Lin Carbon-based nanomaterials have exceptional properties that make them attractive for a variety of technological applications. Here, we report on the use of diamondoids (diamond-like, saturated hydrocarbons) as promising precursors for laser-induced high-pressure, high-temperature diamond synthesis. The lowest pressure and temperature (P-T) conditions that yielded diamond were 12 GPa (at ~2000 K) and 900 K (at ~20 GPa), respectively. This represents a significantly reduced transformation barrier compared with diamond synthesis from conventional (hydro)carbon allotropes. At 20 GPa, diamondoid-to-diamond conversion occurs rapidly within < 19 us. Molecular dynamics simulations indicate that once dehydrogenated, the remaining diamondoid carbon cages reconstruct themselves into diamond-like structures at high P-T. The surprisingly low P-T regime necessary to grow diamond from diamondoids is attributed to the similarities in the structure and full sp3 hybridization of diamondoids and bulk diamond. This study is the first successful mapping of the P-T conditions and onset timing of the diamondoid-to-diamond conversion and elucidates the physical and chemical factors that facilitate diamond synthesis. |
Tuesday, March 16, 2021 3:24PM - 3:36PM Live |
J23.00003: Kinetics of carbon clustering in detonation of high explosives: Particle growth along hydrodynamic streamlines Kirill Velizhanin Chemical reactions in detonation of carbon-rich high explosives yield solid carbon as a major constituent of the products. Efforts to theoretically describe the kinetics of carbon clustering go back to the seminal paper by Shaw and Johnson, where it was modeled as a diffusion-limited irreversible coagulation of smaller clusters into larger ones. In this talk, we will discuss recent direct experimental observations of carbon cluster growth in detonation of high explosives, based on time-resolved small-angle X-ray scattering (TR-SAXS). We will focus on comparison of these results with calculations based on (i) realistic hydrodynamic modeling of detonation of PBX 9502 high explosive, (ii) the Shaw-Johnson model of carbon particulate growth along the streamline obtained from the hydrodynamic simulations, and (iii) accurate simulations of the TR-SAXS signal. We demonstrate that this three-step simulation approach agrees well with the recent experimental results. The implications of this agreement on our present understanding of in-detonation carbon clustering processes will be discussed. |
Tuesday, March 16, 2021 3:36PM - 3:48PM Live |
J23.00004: Examination of the validity of quantum statistical potentials for carbon Heather Whitley, Michael Sean Murillo, Lorin Benedict, John I Castor, Frank R Graziani In recent years, high power laser facilities, such as NIF, and advanced diagnostics have enabled the determination of detailed properties of dense plasmas over unprecedented regimes. Understanding such plasmas, which may be partially degenerate and/or moderately coupled, represents a major challenge to the plasma physics community. One particular challenge for research in this area is the development of interaction potentials which appropriately incorporate the effects of high electron temperature. We examine the accuracy and applicability of approximate effective potentials in the study of structural and dynamic properties carbon in the partially and fully ionized regimes. The diffractive Coulomb potential is derived from an exact quantum solution for a pair of particles while the fermionic character of the electrons is handled via an effective Pauli potential. We compare computed pressures and internal energies for carbon to an equation of state model that was developed based on path integral Monte Carlo and density functional theory. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-795399 |
Tuesday, March 16, 2021 3:48PM - 4:00PM Live |
J23.00005: First-principles phase diagram of carbon at extreme conditions Kien Nguyen Cong, Jonathan Willman, Ashley Williams, Anatoly B Belonoshko, Mitchell Wood, Aidan Thompson, Ivan Oleynik Recent discovery a plethora of the planets outside of our solar system brought a possibility of existence of carbon exoplanets. Therefore, accurate phase diagram of carbon at extreme temperatures and pressures is of critical importance for developing models of the exoplanet interiors. We address a knowledge gap by performing first-principles quantum molecular dynamics (QMD) simulations of thermodynamic properties of carbon at terapascal pressures and up to 10,000 K temperatures with the goal of constructing an accurate phase diagram of carbon. To address the issue of accuracy and reliability, a relatively large number of atoms is used for calculation of melting transitions (melt curve) as a function of pressure using two-phase method. We discuss a possibility of novel phase transitions and possible recovery of new high pressures phases of carbon. |
Tuesday, March 16, 2021 4:00PM - 4:12PM Live |
J23.00006: Detonation NanoDiamond Growth and Aggregation Kinetics during High Explosive Detonations Joshua Hammons, Michael Bagge-Hansen, Michael Nielsen, Saransh Fnu, Elissaios Stavrou, Lisa Lauderbach, Ralph Hodgin, Will Bassett, Nicholas Perez-Marty, Sorin Bastea, Yuelin Li, Nicholas Sinclair, Daniel Anthony Orlikowski, Laurence E. Fried, Trevor M Willey Detonation nanodiamond has many practical applications that rely on its small size. However, during a detonation synthesis, the diamonds can grow too big or aggregate together, requiring significant post processing. In this study, the hierarchical aggregate structure and size of the nanodiamond was investigated using time-resolved X-ray scattering, with an overall global time resolution in this geometry of +/-50 ns. These experiments were performed on different high explosives that condense different carbon allotropes. Our experiments on octol and comp B show that detonation nanodiamond not only forms but rapidly aggregates potentially in the reaction zone and as the detonation products pass through the theoretical Chapman-Jouguet plane and densifies slightly over the subsequent ~ 100 ns. While TATB does not normally produce detonation nanodiamond, an overdriven detonation geometry produced X-ray scattering characteristic of detonation nanodiamond, but ~30 % smaller than the nanodiamond produced with comp B and octol. |
Tuesday, March 16, 2021 4:12PM - 4:24PM Live |
J23.00007: Thermodynamic and Optical Properties of Warm Dense Carbon Derek Schauss, Gennady Miloshevsky The high-fidelity prediction of thermophysical properties of light elements at extreme pressures is essential for interpreting the results of laboratory experiments involving particle beams, short-pulsed lasers, and Z-pinches. In particular, carbon (C) is used as an ablator in inertial confinement fusion targets and a tamping material in laser compression experiments. The equation of state (EOS) of C in the warm dense matter (WDM) regime is the fundamental ingredient for characterizing C properties. The Hartree-Fock-Slater - Collisional-Radiative Steady-State (HFS-CRSS) model and Density Functional Theory Molecular Dynamics (DFT-MD) are used to predict the WDM EOS of C. HFS-CRSS model implements the ab initio HFS methods accounting for the near-degenerate states and the effects of dense plasma environment. DFT-MD combines the classical MD for nuclei and DFT for electrons. The abundances of C ions, level populations, and fractions of bound and free electrons, EOS of solid-density strongly coupled warm C plasma, and radiative emissivity are predicted using the HFS-CRSS model. The differences in the EOS of C in the WDM regime are quantified by comparing the HFS-CRSS and DFT-MD results. |
Tuesday, March 16, 2021 4:24PM - 4:36PM Live |
J23.00008: Germanium under high pressure: In situ and ex situ inelastic neutron scattering Bianca Haberl, Mary-Ellen Donnelly, Garrett E Granroth The fundamentally interesting semiconductor germanium exhibits a rich phase behavior under high pressure. Upon compression to ~11 GPa, diamond-cubic Ge (Fd-3m) transforms to a dense metallic phase (I41/amd). This transition is not reversible upon decompression. Instead several metastable phases with altered band-gap characteristics are recovered. One phase, simple tetragonal st12-Ge (P43212) possesses a relatively large band gap and relatively high thermal stability making it technologically interesting. While these phases and their transitions have been studied with experimental diffraction techniques, theoretical density functional theory (DFT) and other probes, they have not yet been characterized with inelastic neutron scattering (INS), which has prevented detailed correlation to computational understanding. |
Tuesday, March 16, 2021 4:36PM - 4:48PM Live |
J23.00009: High pressure-temperature behavior of long-chain alkanes Abhisek Basu, Christina E Schiffert, Patrick Murphy, Mainak Mookherjee, Bianca Haberl, Reinhard Boehler Carbonaceous chondrites are undifferentiated meteorites that provide valuable insights into the Earth’s pristine chemistry and host a variety of hydrocarbons including polyaromatic hydrocarbons (PAH) and alkanes. It is speculated that these meteorites might have delivered life-essential organic matter to the Earth. Therefore, it is important to understand the survivability of these hydrocarbons inside the meteorites at extreme pressures and temperatures on entry to the Earth’s atmosphere. However, the P-T stability of the long-chain alkanes is not well known. Thus, we have undertaken an in-depth investigation of tricosane-C23H48. Our preliminary study on the high-pressure behavior of C23H48 indicates that upon compression it transforms from a ‘linear’ to a ‘bent’ configuration (Basu et al., 2020). To investigate the combined effect of alkane chain-length and P-T, we explored octadecane-C18H38. Upon compression, we observe a similar transition from a linear to bent configuration, albeit at a lower pressure. On laser-heating in a diamond cell, we note dissociation of C18H38 into smaller alkane chains, elemental carbon (C), and molecular hydrogen (H2), with the formation of binary van der Waals mixtures. |
Tuesday, March 16, 2021 4:48PM - 5:00PM Live |
J23.00010: The mechanical response of glassy carbon recovered from high pressure Xingshuo Huang, Thomas Shiell, Carla de Tomas, Irene Suarez-Martinez, Sherman Wong, Sacha Mann, David McKenzie, Nigel Marks, Dougal McCulloch, Jodie E Bradby Glassy carbon (GC) is a predominately sp2 bonded disordered material. It is considered to have prototypical super-elastic mechanical properties and has been used as a precursor in many high-pressure studies. We have shown that by compressing GC in a diamond anvil cell (DAC) at room temperature, a permanent structural change occurs at pressures above 35-45 GPa. In this current study, GC is compressed to a range of different pressures up to 54 GPa. We show a much lower starting point for the loss of GC’s super-elasticity of ~6 GPa and the material becomes mechanically anisotropic beyond ~30 GPa, measured by nanoindentation probing along both the DAC compression axis and a direction perpendicular to DAC compression axis. Our results show a minimum elasticity of GC at around 30 GPa, with a recovery after compression at higher pressures only along the DAC compression direction. Calculation of the Young’s modulus by molecular dynamics simulations both before and after compression within the same pressure range supported the experimental findings. |
Tuesday, March 16, 2021 5:00PM - 5:12PM Live |
J23.00011: Probing metastability of carbon at extreme conditions Ashley Williams, Kien Nguyen Cong, Jonathan Willman, Anatoly B Belonoshko, Ivan Oleynik In spite of extensive experimental and theoretical efforts, the behavior of carbon at extreme conditions is not completely understood. Previous studies demonstrated the stability of diamond and the absence of other phases of carbon at high pressures up to 1 TPa. However, new metastable phases might appear upon uniaxial compression generated by shock waves. We explore new metastable phases of carbon under both hydrostatic and uniaxial compressions up to 5 TPa using first-principles crystal structure prediction method. Several new metastable phases appear to survive upon decompression to ambient conditions. The experimental validation of these predictions will open up a new avenue in synthesizing new metastable phases of carbon. |
Tuesday, March 16, 2021 5:12PM - 5:24PM Live |
J23.00012: Graphene under pressure: Raman and resistive measurements to 40 GPa Nathan Dasenbrock-Gammon, Ranga P Dias Two-dimensional (2D) materials, such as graphene, offer a variety of outstanding properties for a wide range of applications. The exemplary 2D material, graphene, continues to provide a wealth of interesting physics. In this talk we present novel experimental methods that allow us to study this unique material within a diamond anvil cell to high pressure. Using these experimental methods, we present combined Raman spectroscopic data and direct resistivity measurements on pure monolayer graphene up to 40 GPa at room temperature. With simple physical models we are able to extract effective 3D stiffness parameters from the 2D graphene, and relate these parameters to the observed resistances. |
Tuesday, March 16, 2021 5:24PM - 5:36PM Live |
J23.00013: Detonation synthesis of β-SiC using carbon condensate from RDX/TNT detonation Martin Langenderfer, Catherine E Johnson, Jeremy Watts, Yue Zhou, William G Fahrenholtz Direct detonation synthesis of β-SiC was demonstrated using an RDX/TNT explosive charge loaded with elemental silicon powder detonated in an argon environment. The carbon source for the SiC formation was condensed from the detonation of the high explosive composition. β-SiC production was observed in ex-situ analysis using X-ray diffraction and was confirmed through X-ray photoelectron spectroscopy and transmission electron microscopy imaging of characteristic stacking faults along the (111) zone axis. Hydrodynamic modeling was used to estimate temperature and pressure states as a function of time within the detonation product flow of the RDX/TNT explosive charge. Simulated detonation pressures were validated experimentally via the plate dent test with comparison to empirically predicted Chapman-Jouguet steady-state detonation pressures. A simulated phase diagram was established using Gibbs Free Energy minimization to evaluate the potential for SiC/Si3N4 production at the conditions observed in the detonation product flow. Experiments varying the ratio of nitrogen to carbon in the explosive composition to adjust phase production are also discussed. |
Tuesday, March 16, 2021 5:36PM - 5:48PM Live |
J23.00014: Probing the strain field and structural variation in shock-produced amorphous silicon by scanning nano-probe electron diffraction Shiteng Zhao, Ruopeng Zhang, Benjamin H Savitzky, Bruce Remington, Marc A Meyers, Colin Ophus, Thomas Pekin, Andrew M Minor Shock-induced amorphization can occur when crystalline solids are uniaxially strained in an extremely short time scale. This phenomenon also opens a new door for prototyping the exotic amorphous structures when the conventional methods failed. Taking silicon as an example, we have recovered its amorphous phase from laser shock compression experiments and illustrated the formation mechanisms by both experiments and simulations. However, one missing information is whether the amorphous silicon produced by shock wave is fully relaxed, i.e. are they structurally different than the amorphous structure produced by other techniques such as chemical vapor deposition. We use a newly developed scanning nano-probe electron diffraction technique to tackle this question. A nanometer-sized electron probe is focused onto and rastering over the electron-transparent sample and simultaneously, convergent beam electron diffraction patterns at each pixel are collected, which can be used to compute strain distribution of the region of interest. The strain field in the vicinity of the amorphous band and the radial distribution function within the amorphous domain will be discussed. A tremendous amount of structural variation can be found even within the amorphous domain. |
Tuesday, March 16, 2021 5:48PM - 6:00PM Live |
J23.00015: Aqueous Carbon Under Nanoconfinement at High-Pressure and High-Temperature Conditions Nore Stolte, Ding Pan The carbon cycle in deep Earth greatly influences the carbon budget near the Earth’s surface. Aqueous fluids play an important role in the carbon transport in Earth’s crust and upper mantle. In deep Earth, water does not exist alone, and is largely stored within minerals, e.g. silicates. Here, we applied first-principles molecular dynamics simulations to study aqueous carbon solutions under nanoconfinement at high-pressure and high-temperature conditions, as found in Earth’s upper mantle. We compared the confinement effects by graphene layers and silica slabs. We found that CO2(aq) dissociates more in water under confinement than in the bulk solution. The reactions at the SiO2 interfaces also considerably affect the chemical equilibrium of CO2(aq). We will discuss possible implications for the carbon transport in deep Earth. |
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