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Spin crossover in Fe 2 SiO 4 liquid at high pressure
Author(s) -
Ramo David Muñoz,
Stixrude Lars
Publication year - 2014
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 - 10.1002/2014gl060473
Subject(s) - eutectic system , spin crossover , materials science , molecular dynamics , oxide , high pressure , density functional theory , condensed matter physics , thermodynamics , chemistry , physics , computational chemistry , alloy , metallurgy , composite material
We combine spin‐polarized density functional theory with first principle molecular dynamics (FPMD) to study the spin crossover in liquid Fe 2 SiO 4 , up to 300 GPa and 6000 K. In contrast to the much sharper transition seen in crystals, we find that the high‐ to low‐spin transition occurs over a very broad pressure interval (>200 GPa) due to structural disorder in the liquid. We find excellent agreement with the experimental Hugoniot. We combine our results with previous FPMD calculations to derive the partial molar volumes of the oxide components MgO, FeO, and SiO 2 . We find that eutectic melts in the MgO‐FeO‐SiO 2 system are denser than coexisting solids in the bottom 600 km of Earth's mantle.