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Mössbauer modeling to interpret the spin state of iron in (Mg,Fe)SiO 3 perovskite
Author(s) -
Bengtson Amelia,
Li Jie,
Morgan Dane
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl038340
Subject(s) - quadrupole splitting , mössbauer spectroscopy , perovskite (structure) , quadrupole , valence (chemistry) , spin states , electronic structure , condensed matter physics , spin (aerodynamics) , ab initio , materials science , yield (engineering) , chemistry , atomic physics , physics , crystallography , thermodynamics , quantum mechanics , metallurgy
The properties of (Mg,Fe)SiO 3 perovskite at lower mantle conditions are still not well understood, and particular attention has recently been given to determining the Fe spin state. A major challenge in spin states studies is interpretation of Mössbauer spectra to determine the electronic structure of iron under extreme conditions. In this paper ab initio methods are used to predict quadrupole splitting values of high‐, intermediate‐ and low‐spin Fe 2+ and Fe 3+ in perovskite, as a function of pressure and composition. The calculations in (Mg 0.75 Fe 0.25 )SiO 3 yield quadrupole splitting values in the range of 0.7–1.7 mm/s for all spin and valence states except high‐spin Fe 2+ , which has two possible quadrupole splittings, 2.3 and 3.3 mm/s. The unexpected multiple quadrupole splitting values for high‐spin Fe 2+ are explained in terms of small changes in local structure and d ‐orbital occupations. The computed results are applied to interpret existing perovskite Mössbauer data for iron's spin state.