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High pressure phase transformation in FeF⊂2 (Rutile)
Author(s) -
Ming Lichung,
Manghnani Murli H.
Publication year - 1978
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/gl005i006p00491
Subject(s) - rutile , diamond anvil cell , materials science , diffraction , crystallography , phase (matter) , fluorite , high pressure , chemistry , thermodynamics , physics , metallurgy , organic chemistry , optics
The structural relationships in FeF 2 have been studied under pressure up to 320 kbar and 25°C by use of the diamond anvil pressure cell. In situ X‐ray diffraction analysis shows that at about 50 kbar, FeF 2 (I) with rutile structure transforms into FeF 2 (II) of distorted fluorite structure and at about 250 kbar FeF 2 (II) further transforms into FeF 2 (III) with a hexagonal unit‐cell structure. The zero‐pressure density increase for the transition FeF 2 (I) → FeF 2 (II) is ∼ 8%, and the density increase for FeF 2 (II) → FeF 2 (III) at 320 kbar is ∼ 5%, if the number of formula units per unit cell is assigned at 2 for the hexagonal unit cell.