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Title: High-pressure single-crystal elasticity study of CO[subscript 2] across phase I-III transition

Authors:
; ; ; ;  [1];  [2];  [2];  [2]
  1. (Hawaii)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
DOE - BASIC ENERGY SCIENCESFOREIGN
OSTI Identifier:
1150132
Resource Type:
Journal Article
Resource Relation:
Journal Name: Appl. Phys. Lett.; Journal Volume: 104; Journal Issue: (14) ; 04, 2014
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Zhang, Jin S., Shieh, Sean R., Bass, Jay D., Dera, Przemyslaw, Prakapenka, Vitali, UC), UWO), and UIUC). High-pressure single-crystal elasticity study of CO[subscript 2] across phase I-III transition. United States: N. p., 2016. Web. doi:10.1063/1.4870526.
Zhang, Jin S., Shieh, Sean R., Bass, Jay D., Dera, Przemyslaw, Prakapenka, Vitali, UC), UWO), & UIUC). High-pressure single-crystal elasticity study of CO[subscript 2] across phase I-III transition. United States. doi:10.1063/1.4870526.
Zhang, Jin S., Shieh, Sean R., Bass, Jay D., Dera, Przemyslaw, Prakapenka, Vitali, UC), UWO), and UIUC). 2016. "High-pressure single-crystal elasticity study of CO[subscript 2] across phase I-III transition". United States. doi:10.1063/1.4870526.
@article{osti_1150132,
title = {High-pressure single-crystal elasticity study of CO[subscript 2] across phase I-III transition},
author = {Zhang, Jin S. and Shieh, Sean R. and Bass, Jay D. and Dera, Przemyslaw and Prakapenka, Vitali and UC) and UWO) and UIUC)},
abstractNote = {},
doi = {10.1063/1.4870526},
journal = {Appl. Phys. Lett.},
number = (14) ; 04, 2014,
volume = 104,
place = {United States},
year = 2016,
month = 7
}
  • 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},more » 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.« less
  • To help our understanding of the structural and superconducting transitions in ferropnictides, partial phonon density of states (PDOS) of iron in a single-crystal SrFe2As2 pnictide have been investigated from both out-ofplane and in-plane polarizations with respect to the basal plane of the crystal structure using nuclear resonant inelastic x-ray scattering in a high-pressure diamond anvil cell at ambient temperature. The partial PDOS of iron in the pnictide crystal changes dramatically at approximately 8 GPa, which can be associated with the tetragonal(T)tocollapsedtetragonal(CT)isostructuraltransitionasevidencedinhigh-pressurex-raydiffraction measurements and theoretic calculations. Across the T-CT phase transition, analysis of the PDOS spectra shows a rapid stiffening ofmore » the optical phonon modes and a dramatic increase of the Lamb-M¨ossbauer factor (fLM) and mean force constant which can be associated with the rapid decrease of the c axis and the anomalous expansion of the a axis. Theoretically calculated Fe partial PDOS and lattice parameters of SrFe2As2 further reveal the strong correlation between the lattice parameters and phonons. Our results show that the T-CT transition can induce significant changes in the vibrational, elastic, and thermodynamic properties of SrFe2As2 single crystal at high pressure.« less
  • We performed the single-crystal X-ray diffraction study of a perovskite-type gold mixed-valence compound, Cs{sub 2}Au{sup I}Au{sup III}Cl{sub 6}, under high pressures up to 18 GPa by using a diamond-anvil-cell with helium gas as an ideal hydrostatic pressure-transmitting medium. The lattice parameters and the variable atomic positional parameters were obtained with reasonable accuracy at various pressures. A structural phase transition at ca. 12.5 GPa from I4/mmm to Pm3m was found. The lattice parameters a {sub 0} and c {sub 0}, denoted in the tetragonal cell setting, result in the relationship 2{sup 1/2} a {sub 0}=c {sub 0}, and the superstructure reflectionsmore » h k l (l is odd), caused by the shift of the Cl ions from the midpoint of the Au ions, disappeared at pressures above the phase transition. Both elongated [Au{sup III}Cl{sub 6}] and compressed [Au{sup I}Cl{sub 6}] octahedra in the low-pressure phase smoothly approach regular octahedra with increasing pressure. Above the structural phase transition at 12.5 GPa, all the [AuCl{sub 6}] octahedra are crystallographically equivalent, which shows that the tetragonal-to-cubic phase transition accompanies the valence transition from the Au{sup I}/Au{sup III} mixed-valence state to the Au{sup II} single-valence state. - Graphical abstract: Single-crystal X-ray diffraction study under high pressures up to 18 GPa by using a diamond-anvil-cell with helium gas as an ideal hydrostatic pressure medium has revealed that a perovskite-type gold mixed-valence compound, Cs{sub 2}Au{sup I}Au{sup III}Cl{sub 6}, exhibits the structural phase transition from tetragonal to cubic at 12.5 GPa accompanying gold valence transition.« less