TY - JOUR
T1 - Ultrahigh-pressure disordered eight-coordinated phase of Mg2GeO4
T2 - Analogue for super-Earth mantles
AU - Dutta, Rajkrishna
AU - Tracy, Sally June
AU - Cohen, R. E.
AU - Miozzi, Francesca
AU - Luo, Kai
AU - Yang, Jing
AU - Burnley, Pamela C.
AU - Smith, Dean
AU - Meng, Yue
AU - Chariton, Stella
AU - Prakapenka, Vitali B.
AU - Duffy, Thomas S.
N1 - Funding Information:
We acknowledge helpful discussions with Michael Walter. We are also grateful to Peng Ni for his assistance with staring sample synthesis. This research was supported by the NSF-Earth Sciences (EAR-1836852). R.D. is grateful for support from the Carnegie Endowment. We acknowledge the support of GeoSoilEnviroCARS (Sector 13), which is supported by the NSF-Earth Sciences (EAR-1634415) and the US Department of Energy (DOE), Geosciences (DE-FG02-94ER14466). Portions of this work were performed at HPCAT (Sector 16), APS, Argonne National Laboratory. HPCAT operations are supported by DOE-National Nuclear Security Administration Office of Experimental Sciences. This research used resources of the APS, a DOE Office of Science User Facility operated by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. R.E.C. gratefully acknowledges the Gauss Centre for Supercomputing e.V. (https://www.gauss-centre.eu/) for funding this project by providing computing time on the GCS Supercomputer SuperMUC-NG at Leibniz Supercomputing Centre (LRZ, http://www.lrz.de).
Funding Information:
ACKNOWLEDGMENTS. We acknowledge helpful discussions with Michael Walter. We are also grateful to Peng Ni for his assistance with staring sample synthesis. This research was supported by the NSF—Earth Sciences (EAR-1836852). R.D. is grateful for support from the Carnegie Endowment. We acknowledge the support of GeoSoilEnviroCARS (Sector 13), which is supported by the NSF—Earth Sciences (EAR-1634415) and the US Department of Energy (DOE), Geosciences (DE-FG02-94ER14466). Portions of this work were performed at HPCAT (Sector 16), APS, Argonne National Laboratory. HPCAT operations are supported by DOE-National Nuclear Security Administration Office of Experimental Sciences. This research used resources of the APS, a DOE Office of Science User Facility operated by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. R.E.C. gratefully acknowledges the Gauss Centre for Supercomputing e.V. (https://www.gauss-centre.eu/) for funding this project by providing computing time on the GCS Supercomputer SuperMUC-NG at Leibniz Supercomputing Centre (LRZ, http://www.lrz.de).
Publisher Copyright:
© 2022 National Academy of Sciences. All rights reserved.
PY - 2022/2/22
Y1 - 2022/2/22
N2 - Mg2GeO4 is important as an analog for the ultrahigh-pressure behavior of Mg2SiO4, a major component of planetary interiors. In this study, we have investigated magnesium germanate to 275 GPa and over 2,000 K using a laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction and density functional theory (DFT) computations. The experimental results are consistent with the formation of a phase with disordered Mg and Ge, in which germanium adopts eightfold coordination with oxygen: the cubic, Th3P4-type structure. DFT computations suggest partial Mg-Ge order, resulting in a tetragonal I42 - d structure indistinguishable from I43 - d Th3P4 in our experiments. If applicable to silicates, the formation of this highly coordinated and intrinsically disordered phase may have important implications for the interior mineralogy of large, rocky extrasolar planets.
AB - Mg2GeO4 is important as an analog for the ultrahigh-pressure behavior of Mg2SiO4, a major component of planetary interiors. In this study, we have investigated magnesium germanate to 275 GPa and over 2,000 K using a laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction and density functional theory (DFT) computations. The experimental results are consistent with the formation of a phase with disordered Mg and Ge, in which germanium adopts eightfold coordination with oxygen: the cubic, Th3P4-type structure. DFT computations suggest partial Mg-Ge order, resulting in a tetragonal I42 - d structure indistinguishable from I43 - d Th3P4 in our experiments. If applicable to silicates, the formation of this highly coordinated and intrinsically disordered phase may have important implications for the interior mineralogy of large, rocky extrasolar planets.
KW - Order-disorder transition
KW - Post-postperovskite
KW - Super-Earth mineralogy
UR - http://www.scopus.com/inward/record.url?scp=85124680394&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85124680394&partnerID=8YFLogxK
U2 - 10.1073/pnas.2114424119
DO - 10.1073/pnas.2114424119
M3 - Article
C2 - 35165195
AN - SCOPUS:85124680394
SN - 0027-8424
VL - 119
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 8
M1 - e2114424119
ER -