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