TY - JOUR
T1 - Elastic anomalies in a spin-crossover system
T2 - Ferropericlase at lower mantle conditions
AU - Wu, Zhongqing
AU - Justo, João F.
AU - Wentzcovitch, Renata M.
PY - 2013/5/30
Y1 - 2013/5/30
N2 - The discovery of a pressure induced iron-related spin crossover in Mg (1-x)FexO ferropericlase (Fp) and Mg-silicate perovskite, the major phases of Earth's lower mantle, has raised new questions about mantle properties which are of central importance to seismology. Despite extensive experimental work on the anomalous elasticity of Fp throughout the crossover, inconsistencies reported in the literature are still unexplained. Here we introduce a formulation for thermoelasticity of spin crossover systems, apply it to Fp by combining it with predictive first principles density-functional theory with on-site repulsion parameter U calculations, and contrast results with available data on samples with various iron concentrations. We explain why the shear modulus of Fp should not soften along the crossover, as observed in some experiments, predict its velocities at lower mantle conditions, and show the importance of constraining the elastic properties of minerals without extrapolations for analyses of the thermochemical state of this region.
AB - The discovery of a pressure induced iron-related spin crossover in Mg (1-x)FexO ferropericlase (Fp) and Mg-silicate perovskite, the major phases of Earth's lower mantle, has raised new questions about mantle properties which are of central importance to seismology. Despite extensive experimental work on the anomalous elasticity of Fp throughout the crossover, inconsistencies reported in the literature are still unexplained. Here we introduce a formulation for thermoelasticity of spin crossover systems, apply it to Fp by combining it with predictive first principles density-functional theory with on-site repulsion parameter U calculations, and contrast results with available data on samples with various iron concentrations. We explain why the shear modulus of Fp should not soften along the crossover, as observed in some experiments, predict its velocities at lower mantle conditions, and show the importance of constraining the elastic properties of minerals without extrapolations for analyses of the thermochemical state of this region.
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U2 - 10.1103/PhysRevLett.110.228501
DO - 10.1103/PhysRevLett.110.228501
M3 - Article
C2 - 23767753
AN - SCOPUS:84878356089
SN - 0031-9007
VL - 110
JO - Physical review letters
JF - Physical review letters
IS - 22
M1 - 228501
ER -