Premium
Ab initio investigation on the high‐temperature thermodynamic properties of Fe 3+ ‐bearing MgSiO 3 perovskite
Author(s) -
Tsuchiya Taku,
Wang Xianlong
Publication year - 2013
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 - 10.1029/2012jb009696
Subject(s) - bulk modulus , thermodynamics , materials science , grüneisen parameter , perovskite (structure) , isothermal process , ab initio , condensed matter physics , chemistry , thermal expansion , crystallography , physics , organic chemistry
High‐pressure ( P ) and high‐temperature ( T ) thermodynamics and spin transition of Fe 3+ ‐bearing MgSiO 3 perovskite (Pv) are investigated by means of the internally consistent LDA + U method combined with the lattice dynamics method. Fe 3+ is found to contribute mainly to the low frequency phonons. The spin transition of iron in the B site occurs at 55 GPa at 300 K and from ~75 to ~90 GPa at lower mantle temperatures. Although high‐spin Fe 3+ expands the volume of Pv, most of the bulk thermodynamic properties of Pv are insensitive to Fe 3+ incorporation at least at X Fe2O3 = 0.0625, with the exception of the Grüneisen parameter. The calculated properties are in good agreement with room temperature experimental data, but a significant increase suggested in the isothermal bulk modulus is not predicted. Results clearly demonstrate that Fe 3+ ‐bearing perovskite alone does not reproduce the density and the bulk sound velocity of the Earth's lower mantle simultaneously.