X-ray diffraction and theoretical studies of the high-pressure structures and phase transitions in magnesium fluoride

Download
  1. Get@NRC: X-ray diffraction and theoretical studies of the high-pressure structures and phase transitions in magnesium fluoride (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1103/PhysRevB.64.134110
AuthorSearch for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for:
TypeArticle
Journal titlePhys. Rev. B
Physical Review B
Volume64
Issue13
Pages134110–; # of pages: 1
AbstractMagnesium fluoride is an archetypal simple ionic solid and as such has been subject to numerous theoretical studies with particular emphasis on the rutile to fluorite phase transition. In the present study by angle-dispersive, x-ray powder diffraction and density-functional plane-wave methods, it is shown that the high-pressure behavior of MgF2 is much more complex. A second-order transition from the tetragonal rutile-type to an orthorhombic CaCl2-type phase is observed at 9.1 GPa, prior to the transformation at close to 14 GPa to the cubic phase, which is found to have a modified fluorite structure of the PdF2 type. The structures of these three phases were refined by the Rietveld method, and the pressure dependence of the structural parameters is in good agreement with theory. A denser, cotunnite (?-PbCl2)- type phase is observed at pressures above 35 GPa. Upon decompression, retransformation to the PdF2-type phase is observed and a mixture of the rutile- and ?-PbO2-type forms is recovered at ambient pressure. The results of density-functional calculations yield the following sequence of stable phases: rutile??-PbO2?PdF2??-PbCl2 and indicate that fluorite-type structure always has a higher energy than the PdF2-type structure and is never stable for MgF2.
Publication date
AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedNo
NPARC number12338626
Export citationExport as RIS
Report a correctionReport a correction
Record identifier15c673dd-83a9-4fa9-85a4-bfb0ff83d0df
Record created2009-09-10
Record modified2016-05-09
Bookmark and share
  • Share this page with Facebook (Opens in a new window)
  • Share this page with Twitter (Opens in a new window)
  • Share this page with Google+ (Opens in a new window)
  • Share this page with Delicious (Opens in a new window)
Date modified: