Premium
Effect of chemistry on the stability and elasticity of the perovskite and post‐perovskite phases in the MgSiO 3 ‐FeSiO 3 ‐Al 2 O 3 system and implications for the lowermost mantle
Author(s) -
Caracas R.,
Cohen R. E.
Publication year - 2005
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 - 10.1029/2005gl023164
Subject(s) - perovskite (structure) , elasticity (physics) , post perovskite , phase transition , mineralogy , thermodynamics , geology , stability (learning theory) , materials science , transition zone , chemistry , physics , crystallography , geophysics , machine learning , computer science
Using first‐principles calculations we predict the effects of composition on the perovskite to post‐perovskite phase transition. The transition is predicted at 107 GPa for pure MgSiO 3 . The addition of Al 2 O 3 slightly increases this transition pressure, and the addition of Fe 2+ considerably reduces it; the FeSiO 3 end‐member term is stable in the post‐perovskite modification with respect to perovskite at all pressures. We also determine the static equations of state, densities, elasticity and seismic wave velocities. At the transition V p increases slightly, and V s increases significantly, consistent with the seismic observations for D″. The addition of both Fe 2+ and Al 2 O 3 decrease the seismic wave velocities.