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 = 673 K
;
_database_code_amcsd 0007743
_chemical_formula_sum 'Al Na3 F6'
_cell_length_a 5.5022
_cell_length_b 5.6284
_cell_length_c 7.8725
_cell_angle_alpha 90
_cell_angle_beta 90.055
_cell_angle_gamma 90
_cell_volume 243.800
_exptl_crystal_density_diffrn      2.860
_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  -0.00930   0.45760   0.25170
F1   0.09440   0.03980   0.21800
F2   0.23100   0.32620   0.54230
F3   0.16510   0.26680   0.94300
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 0.02983 0.03049 0.05174 -0.00039 0.00053 -0.00224
Na1 0.05261 0.04993 0.09096 -0.00861 -0.00252 0.00409
Na2 0.07552 0.07116 0.15492 -0.01224 0.00029 0.00233
F1 0.07688 0.09387 0.06455 0.00337 -0.01578 -0.01190
F2 0.05365 0.06350 0.14936 -0.02491 0.01545 -0.00368
F3 0.06222 0.05375 0.17426 -0.02049 0.00287 0.01863