Cryolite
Yang H, Ghose S, Hatch D M
Physics and Chemistry of Minerals 19 (1993) 528-544
Ferroelastic phase transition in cryolite, Na3AlF6, a mixed
fluoride perovskite: high temperature single crystal X-ray
diffraction study and symmetry analysis of the transition mechanism
Sample: T = 890 K
_database_code_amcsd 0007749
5.6323 5.6270 7.9580 90 90 90 Immm
atom     x     y     z B(1,1) B(2,2) B(3,3)  B(1,2) B(1,3) B(2,3)
Al       0     0     0 .02372 .02176 .02917       0      0      0
Na1      0     0    .5 .10646 .04986 .04427       0      0      0
Na2      0    .5 .2515 .10782 .07195 .08872       0      0      0
F1       0     0 .2192 .26249 .19499 .02296       0      0      0
F2   .2335 .2166     0 .15988 .11268 .21482 -.07917      0      0