TY - JOUR
T1 - Crystal structure and bonding in the high-pressure form of fluorite (CaF2)
AU - Morris, Elaine
AU - Groy, Tom
AU - Leinenweber, Kurt
N1 - Funding Information:
This research was funded by a National Science Foundation grant EAR-0074089 to K. Leinenweber.
PY - 2001/6/1
Y1 - 2001/6/1
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.
KW - A. Inorganic compounds
KW - B. Crystal growth
KW - C. High pressure
KW - C. X-ray diffraction
KW - D. Crystal structure
UR - http://www.scopus.com/inward/record.url?scp=0035372073&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035372073&partnerID=8YFLogxK
U2 - 10.1016/S0022-3697(00)00291-2
DO - 10.1016/S0022-3697(00)00291-2
M3 - Article
AN - SCOPUS:0035372073
SN - 0022-3697
VL - 62
SP - 1117
EP - 1122
JO - Journal of Physics and Chemistry of Solids
JF - Journal of Physics and Chemistry of Solids
IS - 6
ER -