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Title: Abnormal Elastic and Vibrational Behaviors of Magnetite at High Pressures

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Energy Frontier Research in Extreme Environments (EFree)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1387145
DOE Contract Number:
SC0001057
Resource Type:
Journal Article
Resource Relation:
Journal Name: Scientific Reports; Journal Volume: 4; Journal Issue: 1; Related Information: EFree partners with Carnegie Institution of Washington (lead); California Institute of Technology; Colorado School of Mines; Cornell University; Lehigh University; Pennsylvania State University
Country of Publication:
United States
Language:
English
Subject:
catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel cells, superconductivity, charge transport, mesostructured materials, materials and chemistry by design, synthesis (novel materials)

Citation Formats

Lin, Jung-Fu, Wu, Junjie, Zhu, Jie, Mao, Zhu, Said, Ayman H., Leu, Bogdan M., Cheng, Jinguang, Uwatoko, Yoshiya, Jin, Changqing, and Zhou, Jianshi. Abnormal Elastic and Vibrational Behaviors of Magnetite at High Pressures. United States: N. p., 2014. Web. doi:10.1038/srep06282.
Lin, Jung-Fu, Wu, Junjie, Zhu, Jie, Mao, Zhu, Said, Ayman H., Leu, Bogdan M., Cheng, Jinguang, Uwatoko, Yoshiya, Jin, Changqing, & Zhou, Jianshi. Abnormal Elastic and Vibrational Behaviors of Magnetite at High Pressures. United States. doi:10.1038/srep06282.
Lin, Jung-Fu, Wu, Junjie, Zhu, Jie, Mao, Zhu, Said, Ayman H., Leu, Bogdan M., Cheng, Jinguang, Uwatoko, Yoshiya, Jin, Changqing, and Zhou, Jianshi. Thu . "Abnormal Elastic and Vibrational Behaviors of Magnetite at High Pressures". United States. doi:10.1038/srep06282.
@article{osti_1387145,
title = {Abnormal Elastic and Vibrational Behaviors of Magnetite at High Pressures},
author = {Lin, Jung-Fu and Wu, Junjie and Zhu, Jie and Mao, Zhu and Said, Ayman H. and Leu, Bogdan M. and Cheng, Jinguang and Uwatoko, Yoshiya and Jin, Changqing and Zhou, Jianshi},
abstractNote = {},
doi = {10.1038/srep06282},
journal = {Scientific Reports},
number = 1,
volume = 4,
place = {United States},
year = {Thu Sep 04 00:00:00 EDT 2014},
month = {Thu Sep 04 00:00:00 EDT 2014}
}
  • An irreversible structural transformation from the cubic phase to a hexagonal high-pressure phase was verified in Gd2O3 between 7.0 and 15 GPa. The compressibility and bond distances of both phases were determined by the refinement of the x-ray diffraction data. The high-pressure phase of Gd2O3 is 9.2% denser than the cubic phase at 7 GPa. After release of pressure, the high-pressure phase transformed to a monoclinic structure. The pressure-induced phase transition from the monoclinic to the hexagonal phase is reversible. Unlike the case at atmospheric pressure, the hexagonal phase was found to transform to the monoclinic phase by increase ofmore » temperature at high pressures. The lattice potential energies and electronic density of states of the cubic, monoclinic, and hexagonal high-pressure phases of Gd2O3 were calculated from the known structural models with density-functional method. The observed phase stability, transition pressure, and volume change are well explained by theoretical calculations.« less
  • {ital Ab} {ital initio} electronic-structure calculations, based on density-functional theory and a full-potential linear-muffin-tin-orbital method, have been used to predict crystal-structure phase stabilities, elastic constants, and Brillouin-zone-boundary phonons for iron under compression. Total energies for five crystal structures, bcc, fcc, bct, hcp, and dhcp, have been calculated over a wide volume range. In agreement with experiment and previous theoretical calculations, a magnetic bcc ground state is obtained at ambient pressure and a nonmagnetic hcp ground state is found at high pressure, with a predicted bcc {r_arrow} hcp phase transition at about 10 GPa. Also in agreement with very recent diamond-anvil-cellmore » experiments, a metastable dhcp phase is found at high pressure, which remains magnetic and consequently accessible at high temperature up to about 50 GPa. In addition, the bcc structure becomes mechanically unstable at pressures above 2 Mbar (200 GPa) and a metastable, but still magnetic, bct phase ({ital c}/{ital a} {approx_equal} 0.875) develops. For high-pressure nonmagnetic iron, fcc and hcp elastic constants and fcc phonon frequencies have been calculated to above 4 Mbar. These quantities rise smoothly with pressure, but an increasing tendency towards elastic anisotropy as a function of compression is observed, and this has important implications for the solid inner-core of the earth. The fcc elastic-constant and phonon data have also been used in combination with generalized pseudopotential theory to develop many-body interatomic potentials, from which high-temperature thermodynamic properties and melting can be obtained. In this paper, these potentials have been used to calculate full fcc and hcp phonon spectra and corresponding Debye temperatures as a function of compression. {copyright} {ital 1996 The American Physical Society.}« less
  • Infrared-visible sum frequency generation (SFG) is a surface-specific vibrational spectroscopy that can operate in a pressure range from ultrahigh vacuum (uhv) to atmospheric pressures. SFG is therefore one of the few surface science techniques that permits atomic scale monitoring of surface species during catalytic reactions at high pressures (around 1 atm) and high temperatures. Using single-crystal surfaces of transition metals, platinum and rhodium, reaction rates can be simultaneously determined by gas chromatography, and correlations between the concentration of adsorbates under reaction conditions and the observed turnover numbers can help to elucidate the reaction mechanism. To bridge the gap to traditionalmore » surface science experiments, SFG is also employed under uhv or low pressures. The technique has been successfully applied to the adsorption and oxidation of CO, hydrocarbon conversion such as ethylene hydrogenation and cyclohexene hydrogenation and dehydrogenation on Pt(111). The experiments demonstrate that the key intermediates of high-pressure catalytic reactions are not present under low-pressure (uhv) conditions. Furthermore, the identification of active intermediates and their concentration at ambient conditions allows calculation of turnover frequencies per active surface species rather than simply per surface metal atom.« less