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Isothermal equation of state and phase stability of Fe 5 Si 3 up to 96 GPa and 3000 K
Author(s) -
McGuire C.,
SantamariaPérez D.,
Makhluf A.,
Kavner A.
Publication year - 2017
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 - 10.1002/2017jb014136
Subject(s) - isothermal process , diamond anvil cell , equation of state , diffraction , bulk modulus , thermodynamics , materials science , ambient pressure , thermal stability , phase (matter) , volume (thermodynamics) , analytical chemistry (journal) , thermal expansion , high pressure , chemistry , metallurgy , optics , physics , organic chemistry , chromatography
The composition of Earth's core has first‐order implications for understanding the thermal and chemical history of the deep Earth. The present work measures the pressure‐volume equation of state of Fe 5 Si 3 to 96 GPa in a diamond anvil cell using noble gas pressure media and demonstrates that Fe 5 Si 3 is not stable at high temperature and pressure but reappears during thermal quench. The isothermal equation of state at ambient temperature of Fe 5 Si 3 is given by the bulk modulus K T ,0 = 167 (8) and K T ,0 ′ = 5.1 (2), with V 0 = 56.29 cm 3 mol −1 . At high temperatures and pressures we observed the disappearance of hexagonal Fe 5 Si 3 diffraction peaks and the appearance of peaks corresponding to cubic FeSi and Fe 3 Si structures at 18 GPa and at the lowest measurable temperature (~1300 K), indicating that Fe 5 Si 3 is not stable at high temperature. Upon temperature quench diffraction peaks corresponding to Fe 5 Si 3 reappear, confirming its stability at ambient temperature and high pressure.