Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session D24: Matter at Extreme Conditions: Planetary Materials II
3:00 PM–5:48 PM,
Monday, March 14, 2022
Room: McCormick Place W-186C
Sponsoring
Units:
GSCCM DCOMP
Chair: Anatoly Belonoshko, Royal Institute of Technology
Abstract: D24.00007 : Ultra-high-pressure behavior of Mg2SiO4 and Mg2GeO4: A combined x-ray diffraction and density functional approach.
4:36 PM–4:48 PM
Presenter:
Rajkrishna Dutta
(Carnegie Inst of Washington)
Authors:
Rajkrishna Dutta
(Carnegie Inst of Washington)
Sally J Tracy
(Carnegie Inst of Washington)
Ronald E Cohen
(Carnegie Inst of Washington)
Jing Yang
(Carnegie Institution for Science)
Dean Smith
(Argonne National Laboratory)
Yue Meng
(Argonne National Laboratory)
Stella Chariton
(University of Chicago)
Vitali Prakapenka
(University of Chicago)
Thomas S Duffy
(Princeton University)
We have explored the high-pressure behavior of magnesium germanate to 275 GPa and over 2000 K using laser-heated diamond anvil cell experiments and density functional theory computations [1]. Our X-ray diffraction patterns are consistent with a disordered cubic Th3P4-type structure at pressures > 190 GPa, in which germanium adopts eight-fold coordination with oxygen. Simulations using the special quasirandom structure (SQS) method are consistent with partially ordered tetragonal structure, indistinguishable from Th3P4 in our experiments. Although, experiments are not feasible for the pressure, temperature ranges necessary for the phases to be stable in the silicate system, we are exploring the stability of these phases in Mg2SiO4 computationally.
[1] R. Dutta, S. J. Tracy, R. E. Cohen, F. Miozzi, K. Luo, J. Yang, P. C. Burnley, D. Smith, Y. Meng, S. Chariton, V. B. Prakapenka, and T. S. Duffy, ArXiv:2101.00347 [Cond-Mat, Physics: Physics] (2021).
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