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Title: High-pressure single-crystal elasticity study of CO{sub 2} across phase I-III transition

Sound velocities and elastic moduli of solid single-crystal CO{sub 2} were measured at pressures up to 11.7(3) GPa by Brillouin spectroscopy. The aggregate adiabatic bulk modulus (K{sub S}), shear modulus (G), and their pressure derivatives for CO{sub 2} Phase I are K{sub S0} = 3.4(6) GPa, G{sub 0} = 1.8(2) GPa, (dK{sub S}/dP){sub 0} = 7.8(3), (dG/dP){sub 0} = 2.5(1), (d{sup 2}K{sub S}/dP{sup 2}){sub 0} = −0.23(3) GPa{sup −1}, and (d{sup 2}G/dP{sup 2}){sub 0} = −0.10(1) GPa{sup −1}. A small increase of elastic properties was observed between 9.8(1) and 10.5(3) GPa, in agreement with the CO{sub 2} I-III transition pressure determined from previous x-ray diffraction experiments. Above the transition pressure P{sub T}, we observed a mixture dominated by CO{sub 2}-I, with minor CO{sub 2}-III. The CO{sub 2}-I + III mixture shows slightly increased sound velocities compared to pure CO{sub 2}-I. Elastic anisotropy calculated from the single-crystal elasticity tensor exhibits a decrease with pressure beginning at 7.9(1) GPa, which is lower than P{sub T}. Our results coincide with recent X-ray Raman observations, suggesting that a pressure-induced electronic transition is related to local structural and optical changes.
Authors:
;  [1] ;  [2] ;  [3] ;  [4]
  1. Department of Geology, University of Illinois, Urbana-Champaign, Illinois 61801 (United States)
  2. Departments of Earth Sciences and Physics and Astronomy, University of Western Ontario, London, Ontario N6A 5B7 (Canada)
  3. Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawaii 96822 (United States)
  4. Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637 (United States)
Publication Date:
OSTI Identifier:
22261588
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 14; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANISOTROPY; CARBON DIOXIDE; ELASTICITY; MONOCRYSTALS; PRESSURE RANGE GIGA PA; SOUND WAVES; SPECTROSCOPY; TENSORS; VELOCITY; X-RAY DIFFRACTION