<i>Ab initio</i> investigation of post-PPV transitions in MgGeO<sub>3</sub> and NaMgF<sub>3</sub>
ORAL
Abstract
We present an ab initio investigation of the pressure induced behavior of MgGeO3 and NaMgF3, traditional low-pressure analogs (LPAs) of MgSiO3. The latter undergoes post-post-perovskite (post-PPV) transitions which are exceedingly important in planetary sciences, but at very high pressures of >~500 GPa [1-3]. Although neither MgGeO3 nor NaMgF3 are perfect LPAs of MgSiO3, in overall both display similar dissociation and recombination transitions and the novel types of phases displayed by MgSiO3 but at much lower pressures easily achievable in diamond anvil cells. Both systems also confirm the ultimate tendency of MgSiO3 toward the dissociation into its elementary binaries, i.e., AX and BX2. We also predict potential metastable phase transitions that may occur more easily than dissociation/recombination reactions under insufficiently heated compression.
[1] S. Q. Wu et al., J. Phys.: Condens. Matter, 26, 035402 (2014).
[2] H. Niu et al., Scientic Reports 5, 18347 (2015).
[3] K. Umemoto et al., Earth Planet. Sci. Lett. 478, 40-45 (2017).
[1] S. Q. Wu et al., J. Phys.: Condens. Matter, 26, 035402 (2014).
[2] H. Niu et al., Scientic Reports 5, 18347 (2015).
[3] K. Umemoto et al., Earth Planet. Sci. Lett. 478, 40-45 (2017).
*This research was supported by JSPS-Kakenhi and MEXT as “Exploratory Challenge on Post-K computer”.
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Presenters
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Koichiro Umemoto
- Earth-Life Science Institute, Tokyo Institute of Technology
- ELSI, Tokyo Institute of Technology