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 = 820 K Note: beta angle has been altered in order to reproduce bond lengths ; _database_code_amcsd 0007745 _chemical_formula_sum 'Al Na3 F6' _cell_length_a 5.5443 _cell_length_b 5.6391 _cell_length_c 7.9127 _cell_angle_alpha 90 _cell_angle_beta 90.098 _cell_angle_gamma 90 _cell_volume 247.389 _exptl_crystal_density_diffrn 2.818 _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 -0.00740 0.46570 0.25110 F1 0.08730 0.03310 0.21770 F2 0.23410 0.32470 0.53990 F3 0.16800 0.26420 0.94860 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 0.03745 0.03924 0.06959 0.00082 -0.00029 -0.00011 Na1 0.06824 0.06631 0.12783 -0.01049 -0.00078 0.00158 Na2 0.09697 0.10138 0.20703 -0.01242 0.00200 0.00538 F1 0.10997 0.14732 0.09062 0.00545 -0.02058 -0.01777 F2 0.07532 0.08361 0.21233 -0.03665 0.02429 -0.00653 F3 0.08704 0.07295 0.25026 -0.02707 0.00287 0.03339