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 = 840 K
_database_code_amcsd 0007746
5.5558 5.6437 7.9263 90 90.001 90 P2_1/n
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 .02563 .02502 .02326  .00082  .00040  .00045
Na1       0     0    .5 .04577 .04314 .04277 -.00544 -.00116  .00212
Na2  -.0072 .4675 .2509 .06496 .06740 .06875 -.00792  .00129  .00306
F1    .0858 .0317 .2179 .07351 .09534 .03171  .00326 -.00877 -.00838
F2    .2351 .3240 .5388 .04939 .05567 .07315 -.02429  .01265 -.00352
F3    .1684 .2637 .9500 .05921 .04693 .08735 -.01838  .00123  .01652