The Spin state of iron in Fe-bearing Mg-perovskite and its crystal chemistry at high pressure

Mashimo, Izumi*; Otani, Eiji*; Hirao, Naohisa*; Mitsui, Takaya; Masuda, Ryo*; Seto, Makoto*; Sakai, Takeshi*; Takahashi, Suguru*; Nakano, Satoshi*

Valence, spin states, and crystallographic sites of Fe in (Mg,Fe)SiO perovskite were investigated using energy-domain Fe-synchrotron Mssbauer spectroscopy and powder X-ray diffraction up to 86 GPa. The volumes of Fe bearing perovskite in this study are slightly smaller than those of Mg endmember perovskite. Our Mssbauer data suggest that Fe prefers A sites coupled with Mg vacancies, which is consistent with previous data at ambient conditions. Fe in the A site remains in a high spin state up to 86 GPa, and some fraction of the A site is occupied by Fe at pressures above 30 GPa. Fe in the A sites is also in a high spin state up to 86 GPa. The coupled substitution from Mg to a high spin state of Fe and Mg vacancy would make the volume of perovskite smaller than that of Mg endmember perovskite.