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Two‐stage spin transition of iron in FeAl‐bearing phase D at lower mantle
Author(s) -
Wu Xiang,
Wu Ye,
Lin JungFu,
Liu Jin,
Mao Zhu,
Guo Xinzhuan,
Yoshino Takashi,
McCammon Catherine,
Prakapenka Vitali B.,
Xiao Yuming
Publication year - 2016
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2016jb013209
Subject(s) - feal , transition zone , spin transition , materials science , phase transition , condensed matter physics , bulk modulus , diamond anvil cell , geology , diffraction , geochemistry , metallurgy , composite material , intermetallic , physics , alloy , optics
Hydrous magnesium silicate phase D plays a key role in the transport of water from the upper to the lower mantle via subducted slabs. Here we report pressure dependence hyperfine and lattice parameters of FeAl‐bearing phase D up to megabar pressures using synchrotron nuclear forward scattering and X‐ray diffraction in a diamond anvil cell at room temperature. FeAl‐bearing phase D undergoes a two‐stage high‐spin to low‐spin transition of iron for Fe 2+ at 37–41 GPa and for Fe 3+ at 64–68 GPa. These transitions are accompanied by an increase in density and a significant softening in the bulk modulus and bulk velocity at their respective pressure range. The occurrence of the dense low‐spin FeAl‐bearing phase D with relatively high velocity anisotropies in deep‐subducted slabs can potentially contribute to small‐scale seismic heterogeneities in the middle‐lower mantle beneath the circum‐Pacific area.