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 = 473 K _database_code_amcsd 0007741 5.4544 5.6155 7.8220 90 90.118 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 .01445 .01304 .01227 -.00018 .00065 -.00026 Na1 0 0 .5 .02344 .02155 .01941 -.00373 -.00017 .00232 Na2 -.0111 .4510 .2521 .03310 .02923 .03424 -.00608 .00130 .00122 F1 .0998 .0432 .2184 .03351 .03298 .01463 .00059 -.00371 -.00283 F2 .2286 .3266 .5442 .02516 .02502 .03253 -.01167 .00488 .00053 F3 .1630 .2678 .9398 .02678 .02256 .03817 -.00775 .00202 .00754