data_global _chemical_name_mineral 'Cryolite' loop_ _publ_author_name 'Yang H' 'Ghose S' 'Hatch D M' _journal_name_full 'Physics and Chemistry of Minerals' _journal_volume 19 _journal_year 1993 _journal_page_first 528 _journal_page_last 544 _publ_section_title ; 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 _chemical_formula_sum 'Al Na3 F6' _cell_length_a 5.4544 _cell_length_b 5.6155 _cell_length_c 7.8220 _cell_angle_alpha 90 _cell_angle_beta 90.118 _cell_angle_gamma 90 _cell_volume 239.581 _exptl_crystal_density_diffrn 2.910 _symmetry_space_group_name_H-M 'P 1 21/n 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2-y,1/2+z' '1/2-x,1/2+y,1/2-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Al 0.00000 0.00000 0.00000 Na1 0.00000 0.00000 0.50000 Na2 -0.01110 0.45100 0.25210 F1 0.09980 0.04320 0.21840 F2 0.22860 0.32660 0.54420 F3 0.16300 0.26780 0.93980 loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 Al 0.02178 0.02083 0.03803 -0.00028 0.00140 -0.00058 Na1 0.03533 0.03443 0.06016 -0.00579 -0.00037 0.00516 Na2 0.04989 0.04670 0.10613 -0.00943 0.00281 0.00271 F1 0.05051 0.05269 0.04535 0.00092 -0.00802 -0.00630 F2 0.03792 0.03997 0.10083 -0.01811 0.01055 0.00118 F3 0.04036 0.03604 0.11831 -0.01203 0.00437 0.01678