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 = 573 K ; _database_code_amcsd 0007742 _chemical_formula_sum 'Al Na3 F6' _cell_length_a 5.4766 _cell_length_b 5.6227 _cell_length_c 7.8461 _cell_angle_alpha 90 _cell_angle_beta 90.089 _cell_angle_gamma 90 _cell_volume 241.607 _exptl_crystal_density_diffrn 2.886 _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 -0.00960 0.45420 0.25190 F1 0.09670 0.04180 0.21820 F2 0.22990 0.32640 0.54330 F3 0.16400 0.26800 0.94130 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 0.02451 0.02519 0.04544 -0.00080 -0.00024 -0.00089 Na1 0.04248 0.04320 0.07840 -0.00702 -0.00235 0.00539 Na2 0.06061 0.05873 0.13239 -0.00969 -0.00146 0.00054 F1 0.06342 0.07499 0.05423 0.00228 -0.01239 -0.01133 F2 0.04420 0.05357 0.12519 -0.02016 0.01169 -0.00083 F3 0.05046 0.04451 0.15129 -0.01666 -0.00002 0.01721