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 = 880 K ; _database_code_amcsd 0007748 _chemical_formula_sum 'Al Na3 F6' _cell_length_a 5.5732 _cell_length_b 5.6414 _cell_length_c 7.9365 _cell_angle_alpha 90 _cell_angle_beta 89.990 _cell_angle_gamma 90 _cell_volume 249.529 _exptl_crystal_density_diffrn 2.794 _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 -0.00600 0.47150 0.25170 F1 0.08160 0.02950 0.21720 F2 0.23740 0.32240 0.53880 F3 0.17040 0.26280 0.95210 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 0.04159 0.04268 0.07949 0.00239 0.00085 -0.00082 Na1 0.07917 0.07442 0.14404 -0.00838 0.00038 0.00082 Na2 0.11171 0.11854 0.23250 -0.01512 0.00022 0.00401 F1 0.13555 0.16642 0.10744 0.00836 -0.02326 -0.01765 F2 0.08584 0.10461 0.26881 -0.04156 0.03092 -0.00569 F3 0.10592 0.08276 0.30145 -0.03429 -0.00246 0.04394