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High pressure phase transformations in MgF 2 (rutile)
Author(s) -
Ming Lichung,
Manghnana Murli H.
Publication year - 1979
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/gl006i001p00013
Subject(s) - rutile , diamond anvil cell , phase diagram , materials science , phase (matter) , crystallite , diffraction , analytical chemistry (journal) , volume (thermodynamics) , x ray crystallography , high pressure , mineralogy , crystallography , thermodynamics , chemistry , optics , metallurgy , physics , organic chemistry , chromatography
Employing a diamond‐anvil pressure cell and a YAG laser as a heating source, phase relationships in polycrystalline MgF 2 (rutile) were investigated to ∼330 kbar at both room temperature (∼23°C), and high temperature (∼1300°C). In situ high pressure X‐ray diffraction data show that MgF 2 (I) of rutile structure transforms into MgF 2 (II) of a cubic structure at ∼300 kbar at room temperature, and at ∼190 kbar at high temperature (∼1300°C), resulting in a negative d P /d T slope for the univariant line between MgF 2 (I) and MgF 2 (II) in the P‐T phase diagram. The molar volume differences at room temperature between MgF 2 (I) and MgF 2 (II) at 190 kbar and 300 kbar are ∼8% and ∼5%, respectively.