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 = 880 K
_database_code_amcsd 0007748
5.5732 5.6414 7.9365 90 89.990 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 .02643 .02647 .02491  .00150  .00038 -.00036
Na1       0     0    .5 .05031 .04616 .04514 -.00526  .00017  .00036
Na2  -.0060 .4715 .2517 .07099 .07352 .07286 -.00949  .00010  .00177
F1    .0816 .0295 .2172 .08614 .10322 .03367  .00525 -.01038 -.00778
F2    .2374 .3224 .5388 .05455 .06488 .08424 -.02609  .01380 -.00251
F3    .1704 .2628 .9521 .06731 .05133 .09447 -.02153 -.00110  .01937