skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Phase transitions and equation of state of forsterite to 90 GPa from single-crystal X-ray diffraction and molecular modeling

Authors:
; ; ; ; ; ;  [1];  [2];  [2];  [2];  [2]
  1. Princeton
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
DOE - BASIC ENERGY SCIENCESNSF
OSTI Identifier:
1114839
Resource Type:
Journal Article
Resource Relation:
Journal Name: American Mineralogist; Journal Volume: 99; Journal Issue: 1
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Finkelstein, Gregory J., Dera, Przemyslaw K., Jahn, Sandro, Oganov, Artem R, Holl, Christopher M., Meng, Yue, Duffy, Thomas S., UC), GFZ), CIW), and SBU). Phase transitions and equation of state of forsterite to 90 GPa from single-crystal X-ray diffraction and molecular modeling. United States: N. p., 2016. Web. doi:10.2138/am.2014.4526.
Finkelstein, Gregory J., Dera, Przemyslaw K., Jahn, Sandro, Oganov, Artem R, Holl, Christopher M., Meng, Yue, Duffy, Thomas S., UC), GFZ), CIW), & SBU). Phase transitions and equation of state of forsterite to 90 GPa from single-crystal X-ray diffraction and molecular modeling. United States. doi:10.2138/am.2014.4526.
Finkelstein, Gregory J., Dera, Przemyslaw K., Jahn, Sandro, Oganov, Artem R, Holl, Christopher M., Meng, Yue, Duffy, Thomas S., UC), GFZ), CIW), and SBU). 2016. "Phase transitions and equation of state of forsterite to 90 GPa from single-crystal X-ray diffraction and molecular modeling". United States. doi:10.2138/am.2014.4526.
@article{osti_1114839,
title = {Phase transitions and equation of state of forsterite to 90 GPa from single-crystal X-ray diffraction and molecular modeling},
author = {Finkelstein, Gregory J. and Dera, Przemyslaw K. and Jahn, Sandro and Oganov, Artem R and Holl, Christopher M. and Meng, Yue and Duffy, Thomas S. and UC) and GFZ) and CIW) and SBU)},
abstractNote = {},
doi = {10.2138/am.2014.4526},
journal = {American Mineralogist},
number = 1,
volume = 99,
place = {United States},
year = 2016,
month = 7
}
  • Pressure-volume equations of state of solid normal hydrogen and deuterium are determined from single-crystal x-ray diffraction measurements to maximum pressures of 26.5 GPa (265 kbar) at 300 K. Experimental data for deuterium are presented and used with the previously reported results for hydrogen. The measurements for deuterium indicate that the structure remains hexagonal closed packed to at least 14.2 GPa at 300 K. The {ital P}-{ital V} data are analyzed with both phenomenological equation-of-state formalisms and pair-potential models. The thermal contributions are calculated from a Mie-Gruneisen model and from lattice-dynamics calculations using effective potentials. A {ital P}-{ital V} equation ofmore » state is determined that accurately describes both the high-pressure diffraction data (to {ital V}/{ital V}{sub 0}=0.2) and previous low-pressure compression results ({ital V}/{ital V}{sub 0}=1.0 to 0.4). There is a significant softening of the equation of state relative to the predictions of lattice-dynamics calculations using previously reported pair potentials, and several effective potentials are examined. Possible corrections to the equation of state at higher pressures, above the range of the present experiments, include effects associated with order-disorder transitions, vibron softening, and band overlap.« less
  • Cited by 9
  • Synchrotron-based high-pressure single-crystal X-ray diffraction experiments were conducted on ~Mg 0.9Fe 0.1SiO 3 (En 90) orthopyroxene crystals at room temperature to a maximum pressure of 48.5 GPa. The sample was compressed in a diamond anvil cell with a neon pressure medium and a gold pressure calibrant. In addition to the previously described orthopyroxene to β-opx transition (designated HPCEN2 in previous studies), we observe two further phase transitions at 29.9 GPa and 40.3 GPa. However, we do not observe the γ-opx phase recently described in an Fe-rich orthopyroxene composition. The structures of both of the new phases were solved in spacemore » group Pca21. While their Mg-O layers remain pyroxene-like, their Si-O layers transform in a stepwise fashion to akimotoite-like sheets, with sites in 4-, 5-, or 6-fold coordination, depending on the specific structure and layer. Due to the increased Si-O coordination number, we designate the new structures α- and β-post-orthopyroxene (α-popx and β-popx). α-popx has one Si-O layer that is entirely tetrahedral, and one layer that contains both tetrahedra and 5-coordinated Si in distorted square pyramids. β-popx retains the mixed 4- and 5-coordinated Si layer found in α-popx, while the other Si layer adopts fully octahedral coordination. The α- and β-popx structures show a progressive transformation towards the arrangement of Si layers found in akimotoite, a potentially important phase in the earth’s transition zone. Metastable transformations in pyroxenes are of interest for understanding possible metastability in geological environments such as subducting slabs and meteorite impacts« less