The material structure described by Mg2Nb2CrO8 crystallizes in the monoclinic Cc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one O(6), one O(7), two equivalent O(5), and two equivalent O(8) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(5), one O(8), two equivalent O(6), and two equivalent O(7) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 6-coordinate geometry to one O(3), one O(7), two equivalent O(1), and two equivalent O(5) atoms. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(4), one O(8), two equivalent O(2), and two equivalent O(6) atoms. Cr(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form edge-sharing CrO6 octahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Nb(1) and one Cr(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Nb(2) and one Cr(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Cr(1) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Nb(2) and two equivalent Cr(1) atoms. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(2), two equivalent Mg(1), and two equivalent Nb(1) atoms. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Mg(1), two equivalent Mg(2), and two equivalent Nb(2) atoms. In the seventh O site, O(7) is bonded to one Mg(1), two equivalent Mg(2), and one Nb(1) atom to form a mixture of corner and edge-sharing OMg3Nb trigonal pyramids. In the eighth O site, O(8) is bonded to one Mg(2), two equivalent Mg(1), and one Nb(2) atom to form a mixture of corner and edge-sharing OMg3Nb trigonal pyramids. is represented by the CIF file [CIF]
data_Mg2Nb2CrO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.153
_cell_length_b   10.153
_cell_length_c   5.219
_cell_angle_alpha   89.016
_cell_angle_beta   89.016
_cell_angle_gamma   34.824
_symmetry_Int_Tables_number   1
_cell_volume   307.222
_cell_formula_units_Z   2
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
  Mg  Mg0  1  0.869  0.582  0.754  1.0
  Mg  Mg1  1  0.413  0.126  0.748  1.0
  Mg  Mg2  1  0.126  0.413  0.248  1.0
  Mg  Mg3  1  0.582  0.869  0.254  1.0
  Nb  Nb4  1  0.043  0.717  0.742  1.0
  Nb  Nb5  1  0.283  0.948  0.762  1.0
  Nb  Nb6  1  0.948  0.283  0.262  1.0
  Nb  Nb7  1  0.717  0.043  0.242  1.0
  Cr  Cr8  1  0.651  0.344  0.745  1.0
  Cr  Cr9  1  0.344  0.651  0.245  1.0
  O  O10  1  0.040  0.810  0.074  1.0
  O  O11  1  0.180  0.965  0.432  1.0
  O  O12  1  0.965  0.180  0.932  1.0
  O  O13  1  0.810  0.040  0.574  1.0
  O  O14  1  0.296  0.581  0.574  1.0
  O  O15  1  0.429  0.682  0.913  1.0
  O  O16  1  0.682  0.429  0.413  1.0
  O  O17  1  0.581  0.296  0.074  1.0
  O  O18  1  0.912  0.708  0.454  1.0
  O  O19  1  0.294  0.079  0.045  1.0
  O  O20  1  0.451  0.161  0.380  1.0
  O  O21  1  0.836  0.544  0.121  1.0
  O  O22  1  0.544  0.836  0.621  1.0
  O  O23  1  0.161  0.451  0.880  1.0
  O  O24  1  0.708  0.912  0.954  1.0
  O  O25  1  0.079  0.294  0.545  1.0
[/CIF]
.
The material structure described by Mg2Nb2CrO8 crystallizes in the monoclinic Cc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one O(6), one O(7), two equivalent O(5), and two equivalent O(8) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(5), one O(8), two equivalent O(6), and two equivalent O(7) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 6-coordinate geometry to one O(3), one O(7), two equivalent O(1), and two equivalent O(5) atoms. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(4), one O(8), two equivalent O(2), and two equivalent O(6) atoms. Cr(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form edge-sharing CrO6 octahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Nb(1) and one Cr(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Nb(2) and one Cr(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Cr(1) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Nb(2) and two equivalent Cr(1) atoms. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(2), two equivalent Mg(1), and two equivalent Nb(1) atoms. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Mg(1), two equivalent Mg(2), and two equivalent Nb(2) atoms. In the seventh O site, O(7) is bonded to one Mg(1), two equivalent Mg(2), and one Nb(1) atom to form a mixture of corner and edge-sharing OMg3Nb trigonal pyramids. In the eighth O site, O(8) is bonded to one Mg(2), two equivalent Mg(1), and one Nb(2) atom to form a mixture of corner and edge-sharing OMg3Nb trigonal pyramids. is represented by the CIF file [CIF]
data_Mg2Nb2CrO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.153
_cell_length_b   10.153
_cell_length_c   5.219
_cell_angle_alpha   89.016
_cell_angle_beta   89.016
_cell_angle_gamma   34.824
_symmetry_Int_Tables_number   1
_cell_volume   307.222
_cell_formula_units_Z   2
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
  Mg  Mg0  1  0.869  0.582  0.754  1.0
  Mg  Mg1  1  0.413  0.126  0.748  1.0
  Mg  Mg2  1  0.126  0.413  0.248  1.0
  Mg  Mg3  1  0.582  0.869  0.254  1.0
  Nb  Nb4  1  0.043  0.717  0.742  1.0
  Nb  Nb5  1  0.283  0.948  0.762  1.0
  Nb  Nb6  1  0.948  0.283  0.262  1.0
  Nb  Nb7  1  0.717  0.043  0.242  1.0
  Cr  Cr8  1  0.651  0.344  0.745  1.0
  Cr  Cr9  1  0.344  0.651  0.245  1.0
  O  O10  1  0.040  0.810  0.074  1.0
  O  O11  1  0.180  0.965  0.432  1.0
  O  O12  1  0.965  0.180  0.932  1.0
  O  O13  1  0.810  0.040  0.574  1.0
  O  O14  1  0.296  0.581  0.574  1.0
  O  O15  1  0.429  0.682  0.913  1.0
  O  O16  1  0.682  0.429  0.413  1.0
  O  O17  1  0.581  0.296  0.074  1.0
  O  O18  1  0.912  0.708  0.454  1.0
  O  O19  1  0.294  0.079  0.045  1.0
  O  O20  1  0.451  0.161  0.380  1.0
  O  O21  1  0.836  0.544  0.121  1.0
  O  O22  1  0.544  0.836  0.621  1.0
  O  O23  1  0.161  0.451  0.880  1.0
  O  O24  1  0.708  0.912  0.954  1.0
  O  O25  1  0.079  0.294  0.545  1.0
[/CIF]
.