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 = 860 K ; _database_code_amcsd 0007747 _chemical_formula_sum 'Al Na3 F6' _cell_length_a 5.5659 _cell_length_b 5.6420 _cell_length_c 7.9322 _cell_angle_alpha 90 _cell_angle_beta 89.989 _cell_angle_gamma 90 _cell_volume 249.093 _exptl_crystal_density_diffrn 2.799 _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 -0.00650 0.46940 0.25200 F1 0.08380 0.03130 0.21700 F2 0.23560 0.32310 0.53870 F3 0.16870 0.26380 0.95070 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 0.03963 0.04262 0.07876 0.00165 -0.00025 0.00086 Na1 0.07398 0.06991 0.14000 -0.00636 -0.00367 0.00231 Na2 0.10479 0.11350 0.22581 -0.01395 -0.00199 0.00544 F1 0.12210 0.16070 0.10468 0.00496 -0.02662 -0.01938 F2 0.08302 0.09468 0.25265 -0.04106 0.02981 -0.00424 F3 0.09967 0.07760 0.29631 -0.03198 0.00076 0.04516