The compound described by Na2CrO4 crystallizes in the trigonal R-3 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(4), and two equivalent O(1) atoms to form NaO4 tetrahedra that share corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, and corners with four equivalent Cr(1)O4 tetrahedra. In the second Na site, Na(2) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form NaO4 tetrahedra that share corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, and corners with four equivalent Cr(1)O4 tetrahedra. Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form CrO4 tetrahedra that share corners with four equivalent Na(1)O4 tetrahedra and corners with four equivalent Na(2)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Na(1) and one Cr(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Na(2) and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one Cr(1) atom. is represented by the CIF card [CIF]
data_Na2CrO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.718
_cell_length_b   9.718
_cell_length_c   9.718
_cell_angle_alpha   107.560
_cell_angle_beta   107.560
_cell_angle_gamma   107.560
_symmetry_Int_Tables_number   1
_cell_volume   752.299
_cell_formula_units_Z   6
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Na  Na0  1  0.941  0.112  0.706  1.0
  Na  Na1  1  0.888  0.294  0.059  1.0
  Na  Na2  1  0.775  0.378  0.604  1.0
  Na  Na3  1  0.294  0.059  0.888  1.0
  Na  Na4  1  0.622  0.396  0.225  1.0
  Na  Na5  1  0.396  0.225  0.622  1.0
  Na  Na6  1  0.604  0.775  0.378  1.0
  Na  Na7  1  0.378  0.604  0.775  1.0
  Na  Na8  1  0.706  0.941  0.112  1.0
  Na  Na9  1  0.225  0.622  0.396  1.0
  Na  Na10  1  0.112  0.706  0.941  1.0
  Na  Na11  1  0.059  0.888  0.294  1.0
  Cr  Cr12  1  0.447  0.040  0.265  1.0
  Cr  Cr13  1  0.960  0.735  0.553  1.0
  Cr  Cr14  1  0.735  0.553  0.960  1.0
  Cr  Cr15  1  0.265  0.447  0.040  1.0
  Cr  Cr16  1  0.040  0.265  0.447  1.0
  Cr  Cr17  1  0.553  0.960  0.735  1.0
  O  O18  1  0.914  0.199  0.256  1.0
  O  O19  1  0.939  0.261  0.558  1.0
  O  O20  1  0.744  0.086  0.801  1.0
  O  O21  1  0.442  0.061  0.739  1.0
  O  O22  1  0.516  0.178  0.451  1.0
  O  O23  1  0.853  0.537  0.869  1.0
  O  O24  1  0.463  0.131  0.147  1.0
  O  O25  1  0.739  0.442  0.061  1.0
  O  O26  1  0.822  0.549  0.484  1.0
  O  O27  1  0.549  0.484  0.822  1.0
  O  O28  1  0.801  0.744  0.086  1.0
  O  O29  1  0.131  0.147  0.463  1.0
  O  O30  1  0.869  0.853  0.537  1.0
  O  O31  1  0.199  0.256  0.914  1.0
  O  O32  1  0.451  0.516  0.178  1.0
  O  O33  1  0.178  0.451  0.516  1.0
  O  O34  1  0.261  0.558  0.939  1.0
  O  O35  1  0.537  0.869  0.853  1.0
  O  O36  1  0.147  0.463  0.131  1.0
  O  O37  1  0.484  0.822  0.549  1.0
  O  O38  1  0.558  0.939  0.261  1.0
  O  O39  1  0.256  0.914  0.199  1.0
  O  O40  1  0.061  0.739  0.442  1.0
  O  O41  1  0.086  0.801  0.744  1.0
[/CIF]
.
The compound described by Na2CrO4 crystallizes in the trigonal R-3 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(2), one O(4), and two equivalent O(1) atoms to form NaO4 tetrahedra that share corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, and corners with four equivalent Cr(1)O4 tetrahedra. In the second Na site, Na(2) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form NaO4 tetrahedra that share corners with two equivalent Na(1)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, and corners with four equivalent Cr(1)O4 tetrahedra. Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form CrO4 tetrahedra that share corners with four equivalent Na(1)O4 tetrahedra and corners with four equivalent Na(2)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Na(1) and one Cr(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Na(2) and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Na(1), one Na(2), and one Cr(1) atom. is represented by the CIF card [CIF]
data_Na2CrO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.718
_cell_length_b   9.718
_cell_length_c   9.718
_cell_angle_alpha   107.560
_cell_angle_beta   107.560
_cell_angle_gamma   107.560
_symmetry_Int_Tables_number   1
_cell_volume   752.299
_cell_formula_units_Z   6
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Na  Na0  1  0.941  0.112  0.706  1.0
  Na  Na1  1  0.888  0.294  0.059  1.0
  Na  Na2  1  0.775  0.378  0.604  1.0
  Na  Na3  1  0.294  0.059  0.888  1.0
  Na  Na4  1  0.622  0.396  0.225  1.0
  Na  Na5  1  0.396  0.225  0.622  1.0
  Na  Na6  1  0.604  0.775  0.378  1.0
  Na  Na7  1  0.378  0.604  0.775  1.0
  Na  Na8  1  0.706  0.941  0.112  1.0
  Na  Na9  1  0.225  0.622  0.396  1.0
  Na  Na10  1  0.112  0.706  0.941  1.0
  Na  Na11  1  0.059  0.888  0.294  1.0
  Cr  Cr12  1  0.447  0.040  0.265  1.0
  Cr  Cr13  1  0.960  0.735  0.553  1.0
  Cr  Cr14  1  0.735  0.553  0.960  1.0
  Cr  Cr15  1  0.265  0.447  0.040  1.0
  Cr  Cr16  1  0.040  0.265  0.447  1.0
  Cr  Cr17  1  0.553  0.960  0.735  1.0
  O  O18  1  0.914  0.199  0.256  1.0
  O  O19  1  0.939  0.261  0.558  1.0
  O  O20  1  0.744  0.086  0.801  1.0
  O  O21  1  0.442  0.061  0.739  1.0
  O  O22  1  0.516  0.178  0.451  1.0
  O  O23  1  0.853  0.537  0.869  1.0
  O  O24  1  0.463  0.131  0.147  1.0
  O  O25  1  0.739  0.442  0.061  1.0
  O  O26  1  0.822  0.549  0.484  1.0
  O  O27  1  0.549  0.484  0.822  1.0
  O  O28  1  0.801  0.744  0.086  1.0
  O  O29  1  0.131  0.147  0.463  1.0
  O  O30  1  0.869  0.853  0.537  1.0
  O  O31  1  0.199  0.256  0.914  1.0
  O  O32  1  0.451  0.516  0.178  1.0
  O  O33  1  0.178  0.451  0.516  1.0
  O  O34  1  0.261  0.558  0.939  1.0
  O  O35  1  0.537  0.869  0.853  1.0
  O  O36  1  0.147  0.463  0.131  1.0
  O  O37  1  0.484  0.822  0.549  1.0
  O  O38  1  0.558  0.939  0.261  1.0
  O  O39  1  0.256  0.914  0.199  1.0
  O  O40  1  0.061  0.739  0.442  1.0
  O  O41  1  0.086  0.801  0.744  1.0
[/CIF]
.