摘要： Using density functional theory+Hubbard U (DFT+U) calculations, we investigate the spin states and nuclear hyperfine interactions of iron incorporated in magnesium silicate (MgSiO3) post-perovskite (Ppv), a major mineral phase in the Earth's D″ layer, where the pressure ranges from ~120 to 135GPa. In this pressure range, ferrous iron (Fe2+) substituting for magnesium at the dodecahedral (A) site remains in the high-spin (HS) state; intermediate-spin (IS) and low-spin (LS) states are highly unfavorable. As to ferric iron (Fe3+), which substitutes magnesium at the A site and silicon at the octahedral (B) site to form (Mg,Fe)(Si,Fe)O3 Ppv, we find the combination of HS Fe3+ at the A site and LS Fe3+ at the B site the most favorable. Neither A-site nor B-site Fe3+ undergoes a spin-state crossover in the D″ pressure range. The computed iron quadrupole splittings are consistent with those observed in Mössbauer spectra. The effects of Fe2+ and Fe3+ on the equation of state of Ppv are found nearly identical, expanding the unit cell volume while barely affecting the bulk modulus. 出版者： Elsevier B.V 出版日期： 2012-05-15 出處： Earth and Planetary Science Letters, 2012-05, Vol.331-332, p.1-7 資源來源： ScienceDirect - Freedom Collection 版權： 2012 Elsevier B.V. 識別號： ISSN: 0012-821X 識別號： EISSN: 1385-013X 識別號： DOI: 10.1016/j.epsl.2012.03.002
