data_1010023
_chemical_name_systematic          'Sodium chromate'
_chemical_formula_structural       'Na2 Cr O4'
_chemical_formula_sum              'Cr Na2 O4'
_publ_section_title
;
The crystal structure of anhydrous sodium chromate, Na~2~ Cr O~4~
;
_publ_author_name                  'Miller, J J'
_journal_name_full
;
Zeitschrift fuer Kristallographie, Kristallgeometrie, Kristallphysik,
Kristallchemie (-144,1977)
;
_journal_coden_ASTM                ZEKGAX
_journal_volume                    94
_journal_year                      1936
_journal_page_first                131
_journal_page_last                 136
_cell_length_a                     5.91
_cell_length_b                     9.23
_cell_length_c                     7.2
_cell_angle_alpha                  90
_cell_angle_beta                   90
_cell_angle_gamma                  90
_cell_volume                       392.8
_cell_formula_units_Z              4
_exptl_crystal_density_meas        2.73
_symmetry_space_group_name_H-M     'P b n n'
_symmetry_Int_Tables_number        52
_symmetry_cell_setting             orthorhombic
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  'x,1/2-y,-z'
  '1/2-x,y,1/2-z'
  '1/2-x,1/2-y,1/2+z'
  '-x,-y,-z'
  '-x,1/2+y,z'
  '1/2+x,-y,1/2+z'
  '1/2+x,1/2+y,1/2-z'
loop_
_atom_type_symbol
_atom_type_oxidation_number
  Na1+   1.000
  Cr6+   6.000
  O2-   -2.000
loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_symmetry_multiplicity
_atom_site_Wyckoff_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_attached_hydrogens
_atom_site_calc_flag
  Na1   Na1+   4 d 0.25 0.45 0.25 1.  0 d
  Na2   Na1+   4 c -0.25 0.25 0. 1.  0 d
  Cr1   Cr6+   4 d 0.25 0.0972 0.25 1.  0 d
  O1    O2-    8 e 0.0278 0.2 0.25 1.  0 d
  O2    O2-    8 e 0.25 0. 0.0694 1.  0 d