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 = 295 K ; _database_code_amcsd 0007739 _chemical_formula_sum 'Al Na3 F6' _cell_length_a 5.4139 _cell_length_b 5.6012 _cell_length_c 7.7769 _cell_angle_alpha 90 _cell_angle_beta 90.183 _cell_angle_gamma 90 _cell_volume 235.828 _exptl_crystal_density_diffrn 2.957 _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 -0.01210 0.44920 0.25260 F1 0.10160 0.04420 0.21880 F2 0.22780 0.32670 0.54500 F3 0.16220 0.26870 0.93830 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 0.01832 0.01682 0.03003 0.00011 0.00092 -0.00013 Na1 0.02832 0.02724 0.04780 -0.00429 -0.00032 0.00483 Na2 0.03920 0.03578 0.08466 -0.00734 0.00160 0.00079 F1 0.03985 0.03994 0.03698 0.00049 -0.00785 -0.00415 F2 0.02971 0.03168 0.08119 -0.01401 0.00804 -0.00055 F3 0.03148 0.02831 0.09109 -0.00917 0.00164 0.01328