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The effect of pressure on the structure and volume of ferromagnesian post‐perovskite
Author(s) -
Mao Wendy L.,
Mao Hokwang,
Prakapenka Vitali B.,
Shu Jinfu,
Hemley Russell J.
Publication year - 2006
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 - 10.1029/2006gl025770
Subject(s) - volume (thermodynamics) , bulk modulus , materials science , perovskite (structure) , stacking , diffraction , modulus , crystallography , analytical chemistry (journal) , mineralogy , geology , chemistry , thermodynamics , composite material , nuclear magnetic resonance , optics , physics , chromatography
We determined pressure‐volume ( P‐V ) data for (Mg 0.6 Fe 0.4 )SiO 3 post‐perovskite (ppv) upon decompression from 140 GPa. The data can be divided into four regions: above 95 GPa, diffraction peaks are sharp and follow a smooth and tight P‐V curve; below 90 GPa, peak widths increase, and a kink develops in the P‐V curve; below 60 GPa, the broadening plateaus; below 4.6 GPa, the ppv pattern disappears. This suggests that defects and stacking faults start to develop in ppv at 90 GPa and saturate at 60 GPa, and the structure disintegrates below 4.6 GPa. The volume and density of the (Mg 0.6 Fe 0.4 )SiO 3 ppv is well constrained by our data at the pressures relevant to the Earth's D″ layer. Our bulk modulus in this region is much higher than theoretical calculations for pure MgSiO 3 ppv.