Crystal structure and bonding in the high-pressure form of fluorite (CaF2)

Elaine Morris, Tom Groy, Kurt Leinenweber

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Single crystals of CaF2 in the PbCl2 structure were grown at high pressure in a molten calcium hydroxide flux, and the structure was refined by single crystal X-ray diffraction (Pnma, a = 6.018(2) Å, b = 3.614(1) Å, c = 7.023(2) Å). Calcium is in nine-coordination in this structure, with Ca-F distances range from 2.317 to 2.774 Å. The two distinct fluorine atoms are in four and five coordination with calcium. Both the ambient pressure fluorite phase and the high pressure phase of CaF2 have calcium in a close-packed configuration, cubic in fluorite and hexagonal in the PbCl2 phase. This allows a simple comparison of the Ca arrays between the two phases. It is found that the close-packed array in the PbCl2 phase is contracted along a and b by 4.7 and 6.6%, respectively, and elongated along c by 4.8%, relative to the close-packed array in fluorite.

Original languageEnglish (US)
Pages (from-to)1117-1122
Number of pages6
JournalJournal of Physics and Chemistry of Solids
Volume62
Issue number6
DOIs
StatePublished - Jun 1 2001

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Fluorspar
fluorite
calcium
Calcium
Crystal structure
crystal structure
Single crystals
Calcium Hydroxide
Hydrated lime
Fluorine
Molten materials
single crystals
Fluxes
hydroxides
fluorine
X ray diffraction
Atoms
lead chloride
configurations
diffraction

Keywords

  • A. Inorganic compounds
  • B. Crystal growth
  • C. High pressure
  • C. X-ray diffraction
  • D. Crystal structure

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Crystal structure and bonding in the high-pressure form of fluorite (CaF2). / Morris, Elaine; Groy, Tom; Leinenweber, Kurt.

In: Journal of Physics and Chemistry of Solids, Vol. 62, No. 6, 01.06.2001, p. 1117-1122.

Research output: Contribution to journalArticle

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abstract = "Single crystals of CaF2 in the PbCl2 structure were grown at high pressure in a molten calcium hydroxide flux, and the structure was refined by single crystal X-ray diffraction (Pnma, a = 6.018(2) {\AA}, b = 3.614(1) {\AA}, c = 7.023(2) {\AA}). Calcium is in nine-coordination in this structure, with Ca-F distances range from 2.317 to 2.774 {\AA}. The two distinct fluorine atoms are in four and five coordination with calcium. Both the ambient pressure fluorite phase and the high pressure phase of CaF2 have calcium in a close-packed configuration, cubic in fluorite and hexagonal in the PbCl2 phase. This allows a simple comparison of the Ca arrays between the two phases. It is found that the close-packed array in the PbCl2 phase is contracted along a and b by 4.7 and 6.6{\%}, respectively, and elongated along c by 4.8{\%}, relative to the close-packed array in fluorite.",
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N2 - Single crystals of CaF2 in the PbCl2 structure were grown at high pressure in a molten calcium hydroxide flux, and the structure was refined by single crystal X-ray diffraction (Pnma, a = 6.018(2) Å, b = 3.614(1) Å, c = 7.023(2) Å). Calcium is in nine-coordination in this structure, with Ca-F distances range from 2.317 to 2.774 Å. The two distinct fluorine atoms are in four and five coordination with calcium. Both the ambient pressure fluorite phase and the high pressure phase of CaF2 have calcium in a close-packed configuration, cubic in fluorite and hexagonal in the PbCl2 phase. This allows a simple comparison of the Ca arrays between the two phases. It is found that the close-packed array in the PbCl2 phase is contracted along a and b by 4.7 and 6.6%, respectively, and elongated along c by 4.8%, relative to the close-packed array in fluorite.

AB - Single crystals of CaF2 in the PbCl2 structure were grown at high pressure in a molten calcium hydroxide flux, and the structure was refined by single crystal X-ray diffraction (Pnma, a = 6.018(2) Å, b = 3.614(1) Å, c = 7.023(2) Å). Calcium is in nine-coordination in this structure, with Ca-F distances range from 2.317 to 2.774 Å. The two distinct fluorine atoms are in four and five coordination with calcium. Both the ambient pressure fluorite phase and the high pressure phase of CaF2 have calcium in a close-packed configuration, cubic in fluorite and hexagonal in the PbCl2 phase. This allows a simple comparison of the Ca arrays between the two phases. It is found that the close-packed array in the PbCl2 phase is contracted along a and b by 4.7 and 6.6%, respectively, and elongated along c by 4.8%, relative to the close-packed array in fluorite.

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