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 = 840 K ; _database_code_amcsd 0007746 _chemical_formula_sum 'Al Na3 F6' _cell_length_a 5.5558 _cell_length_b 5.6437 _cell_length_c 7.9263 _cell_angle_alpha 90 _cell_angle_beta 90.001 _cell_angle_gamma 90 _cell_volume 248.531 _exptl_crystal_density_diffrn 2.805 _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 -0.00720 0.46750 0.25090 F1 0.08580 0.03170 0.21790 F2 0.23510 0.32400 0.53880 F3 0.16840 0.26370 0.95000 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 0.04008 0.04037 0.07403 0.00130 0.00089 0.00102 Na1 0.07157 0.06961 0.13613 -0.00864 -0.00259 0.00480 Na2 0.10158 0.10876 0.21882 -0.01258 0.00288 0.00693 F1 0.11495 0.15384 0.10093 0.00518 -0.01957 -0.01899 F2 0.07723 0.08983 0.23282 -0.03858 0.02822 -0.00798 F3 0.09259 0.07573 0.27802 -0.02920 0.00274 0.03744