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Equations of state of α-SiC (6H) and βʹ-Mg₂Si₁.₁ from single-crystal X-ray diffraction data and novel high-pressure magnesium silicide Mg₂Si₇

DOI zum Zitieren der Version auf EPub Bayreuth: https://doi.org/10.15495/EPub_UBT_00006657
URN to cite this document: urn:nbn:de:bvb:703-epub-6657-0

Title data

Koemets, Iuliia ; Ishii, Takayuki ; Hanfland, Michael ; Dubrovinsky, Leonid:
Equations of state of α-SiC (6H) and βʹ-Mg₂Si₁.₁ from single-crystal X-ray diffraction data and novel high-pressure magnesium silicide Mg₂Si₇.
In: Physics and Chemistry of Minerals. Vol. 49 (2022) Issue 5 . - No. 12.
ISSN 1432-2021
DOI der Verlagsversion: https://doi.org/10.1007/s00269-022-01189-3

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Abstract

SiC and (Fe, Mg)-silicide are candidate phases forming under reducing conditions in the Earth and planetary interiors. However, structural studies of SiC and Mg₂Si at high pressure and their thermal stability are presently lacking. In this work, we applied single-crystal X-ray diffraction in a diamond anvil cell at high pressure and determined the equations of state of α-SiC (6H) and βʹ-Mg₂Si₁.₁ up to 60 and 40 GPa, respectively, yielding bulk moduli of 226.0(4) and 56(1) GPa. We also report the formation of a novel orthorhombic Mg₂Si₇ phase upon laser heating βʹ-Mg₂Si₁.₁ at ~ 45 GPa and 2000 °C [Pbam, a = 7.16(1) Å, b = 12.490(3) Å, c = 2.6545(3) Å, V = 237.5(3) Å3]. The structure of this compound contains layers formed by irregular 12-member silicon rings, which are arranged in channels filled with both Mg and Si atoms. No signs of the Mg₂Si₇ phase were detected upon releasing the pressure in the DAC, which suggests that this phase is unstable under ambient conditions.

Further data

Item Type: Article in a journal
Keywords: Singe-crystal X-ray diffraction; Diamond anvil cell; Magnesium silicide; Silicon carbide
DDC Subjects: 500 Science > 500 Natural sciences
500 Science > 550 Earth sciences, geology
Institutions of the University: Research Institutions > Research Centres > Bavarian Research Institute of Experimental Geochemistry and Geophysics - BGI
Research Institutions
Research Institutions > Research Centres
Language: English
Originates at UBT: Yes
URN: urn:nbn:de:bvb:703-epub-6657-0
Date Deposited: 16 Sep 2022 06:42
Last Modified: 16 Sep 2022 06:42
URI: https://epub.uni-bayreuth.de/id/eprint/6657

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