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