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Experimental vibrational Grüneisen ratio values for ϵ‐iron up to 330 GPa at 300 K
Author(s) -
Anderson Orson L.,
Dubrovinsky Leonid,
Saxena Surendra K.,
LeBihan T.
Publication year - 2001
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 - 10.1029/2000gl008544
Subject(s) - diffraction , debye model , materials science , diamond anvil cell , debye , rietveld refinement , analytical chemistry (journal) , diamond , intensity (physics) , inner core , amplitude , x ray crystallography , powder diffraction , compression (physics) , crystallography , thermodynamics , condensed matter physics , chemistry , optics , physics , metallurgy , chromatography , composite material
Experimental values for the vibrational Grüneisen ratio, γ υ , for hexagonal close‐packed (hcp) iron, called epsilon (ϵ)‐iron, were obtained over a large compression range corresponding to Earth's inner‐core pressure. This was done by measuring the intensity change in x‐ray diffraction lines under pressure, P . X‐ray structural refinement using the Rietveld method on powder diffraction data yielded information on mean square displacement used to obtain the Debye temperature, Θ, as a function of compression, V/V 0 . The value of Θ was determined from the measured intensity of the diffraction lines, which arises from the mean squared amplitude < u ² > measured in‐situ in the diamond cell. From the Debye relationship, γ υ =−(∂ ln Θ/∂ ln V ) T , we determined experimental data on γ υ versus V of Fe (hcp) up to 330 GPa at 300 K. The measured value of γ υ ( V ) is 1.18 at 330 GPa and 1.41 at 135 GPa.