The crystal structure described by NaMgCr3O8 crystallizes in the monoclinic C2 space group. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(4) atoms. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(4) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-56°. In the second Cr site, Cr(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing CrO6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Cr(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Cr(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(1), one Mg(1), and one Cr(1) atom. is represented by the CIF file [CIF]
data_NaMgCr3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.139
_cell_length_b   5.139
_cell_length_c   7.061
_cell_angle_alpha   91.144
_cell_angle_beta   91.144
_cell_angle_gamma   69.917
_symmetry_Int_Tables_number   1
_cell_volume   175.078
_cell_formula_units_Z   1
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  0.829  0.171  0.000  1.0
  Mg  Mg1  1  0.314  0.686  0.000  1.0
  Cr  Cr2  1  0.656  0.609  0.699  1.0
  Cr  Cr3  1  0.019  0.981  0.500  1.0
  Cr  Cr4  1  0.391  0.344  0.301  1.0
  O  O5  1  0.780  0.253  0.689  1.0
  O  O6  1  0.747  0.220  0.311  1.0
  O  O7  1  0.232  0.721  0.283  1.0
  O  O8  1  0.279  0.768  0.717  1.0
  O  O9  1  0.244  0.213  0.465  1.0
  O  O10  1  0.787  0.756  0.535  1.0
  O  O11  1  0.709  0.674  0.938  1.0
  O  O12  1  0.326  0.291  0.062  1.0
[/CIF]
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The crystal structure described by NaMgCr3O8 crystallizes in the monoclinic C2 space group. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(4) atoms. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(4) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-56°. In the second Cr site, Cr(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing CrO6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Cr(1), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Cr(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(1), one Mg(1), and one Cr(1) atom. is represented by the CIF file [CIF]
data_NaMgCr3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.139
_cell_length_b   5.139
_cell_length_c   7.061
_cell_angle_alpha   91.144
_cell_angle_beta   91.144
_cell_angle_gamma   69.917
_symmetry_Int_Tables_number   1
_cell_volume   175.078
_cell_formula_units_Z   1
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  0.829  0.171  0.000  1.0
  Mg  Mg1  1  0.314  0.686  0.000  1.0
  Cr  Cr2  1  0.656  0.609  0.699  1.0
  Cr  Cr3  1  0.019  0.981  0.500  1.0
  Cr  Cr4  1  0.391  0.344  0.301  1.0
  O  O5  1  0.780  0.253  0.689  1.0
  O  O6  1  0.747  0.220  0.311  1.0
  O  O7  1  0.232  0.721  0.283  1.0
  O  O8  1  0.279  0.768  0.717  1.0
  O  O9  1  0.244  0.213  0.465  1.0
  O  O10  1  0.787  0.756  0.535  1.0
  O  O11  1  0.709  0.674  0.938  1.0
  O  O12  1  0.326  0.291  0.062  1.0
[/CIF]
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