The material structure described by Na8MgCr2O8 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(3), one O(6), and one O(8) atom. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(3), one O(4), one O(6), and one O(8) atom. In the third Na site, Na(3) is bonded to one O(1), one O(3), one O(4), and one O(8) atom to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Na(7)O5 square pyramid,  a cornercorner with one Cr(1)O4 tetrahedra, corners with three equivalent Cr(2)O4 tetrahedra,  an edgeedge with one Na(6)O5 square pyramid,  an edgeedge with one Na(7)O5 square pyramid, and  an edgeedge with one Mg(1)O4 tetrahedra. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(5), one O(6), and one O(7) atom. In the fifth Na site, Na(5) is bonded in a 4-coordinate geometry to one O(1), one O(4), one O(5), and one O(7) atom. In the sixth Na site, Na(6) is bonded to one O(2), one O(3), one O(5), one O(6), and one O(8) atom to form distorted NaO5 square pyramids that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Cr(1)O4 tetrahedra, corners with two equivalent Cr(2)O4 tetrahedra, edges with two equivalent Na(7)O5 square pyramids,  an edgeedge with one Cr(1)O4 tetrahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. In the seventh Na site, Na(7) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form distorted NaO5 square pyramids that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Cr(2)O4 tetrahedra,  a cornercorner with one Na(3)O4 trigonal pyramid, edges with two equivalent Na(6)O5 square pyramids,  an edgeedge with one Cr(1)O4 tetrahedra,  an edgeedge with one Cr(2)O4 tetrahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. In the eighth Na site, Na(8) is bonded in a 4-coordinate geometry to one O(2), one O(5), one O(6), and one O(7) atom. Mg(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Na(6)O5 square pyramid,  a cornercorner with one Na(7)O5 square pyramid, corners with two equivalent Cr(2)O4 tetrahedra,  an edgeedge with one Cr(1)O4 tetrahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form CrO4 tetrahedra that share  a cornercorner with one Na(6)O5 square pyramid,  a cornercorner with one Na(3)O4 trigonal pyramid,  an edgeedge with one Na(6)O5 square pyramid,  an edgeedge with one Na(7)O5 square pyramid, and  an edgeedge with one Mg(1)O4 tetrahedra. In the second Cr site, Cr(2) is bonded to one O(3), one O(4), one O(7), and one O(8) atom to form CrO4 tetrahedra that share  a cornercorner with one Na(7)O5 square pyramid, corners with two equivalent Na(6)O5 square pyramids, corners with two equivalent Mg(1)O4 tetrahedra, corners with three equivalent Na(3)O4 trigonal pyramids, and  an edgeedge with one Na(7)O5 square pyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(3), one Na(4), one Na(5), one Mg(1), and one Cr(1) atom. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(6), one Na(7), one Na(8), and one Cr(1) atom to form ONa5Cr octahedra that share corners with two equivalent O(4)Na4MgCr octahedra and edges with two equivalent O(3)Na5Cr octahedra. The corner-sharing octahedral tilt angles range from 6-9°. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Na(3), one Na(6), one Na(7), and one Cr(2) atom to form distorted ONa5Cr octahedra that share edges with two equivalent O(4)Na4MgCr octahedra and edges with two equivalent O(2)Na5Cr octahedra. In the fourth O site, O(4) is bonded to one Na(2), one Na(3), one Na(5), one Na(7), one Mg(1), and one Cr(2) atom to form a mixture of distorted corner and edge-sharing ONa4MgCr octahedra. The corner-sharing octahedral tilt angles range from 6-9°. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Na(4), one Na(5), one Na(6), one Na(8), one Mg(1), and one Cr(1) atom. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(4), one Na(6), one Na(7), one Na(8), and one Cr(1) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Na(4), one Na(5), one Na(8), one Mg(1), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(6), one Na(7), and one Cr(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na8MgCr2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.567
_cell_length_b   6.045
_cell_length_c   9.274
_cell_angle_alpha   69.064
_cell_angle_beta   79.751
_cell_angle_gamma   70.553
_symmetry_Int_Tables_number   1
_cell_volume   274.244
_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  0.765  0.000  0.424  1.0
  Na  Na1  1  0.742  0.418  0.587  1.0
  Na  Na2  1  0.261  0.332  0.773  1.0
  Na  Na3  1  0.413  0.882  0.061  1.0
  Na  Na4  1  0.760  0.236  0.984  1.0
  Na  Na5  1  0.251  0.521  0.422  1.0
  Na  Na6  1  0.249  0.909  0.587  1.0
  Na  Na7  1  0.765  0.562  0.218  1.0
  Mg  Mg8  1  0.192  0.600  0.965  1.0
  Cr  Cr9  1  0.269  0.192  0.242  1.0
  Cr  Cr10  1  0.711  0.801  0.758  1.0
  O  O11  1  0.140  0.263  0.042  1.0
  O  O12  1  0.018  0.255  0.400  1.0
  O  O13  1  0.966  0.652  0.628  1.0
  O  O14  1  0.479  0.598  0.802  1.0
  O  O15  1  0.381  0.492  0.159  1.0
  O  O16  1  0.473  0.856  0.334  1.0
  O  O17  1  0.845  0.847  0.937  1.0
  O  O18  1  0.526  0.116  0.635  1.0
[/CIF]
.
The material structure described by Na8MgCr2O8 crystallizes in the triclinic P1 space group. There are eight inequivalent Na sites. In the first Na site, Na(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(3), one O(6), and one O(8) atom. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(3), one O(4), one O(6), and one O(8) atom. In the third Na site, Na(3) is bonded to one O(1), one O(3), one O(4), and one O(8) atom to form distorted NaO4 trigonal pyramids that share  a cornercorner with one Na(7)O5 square pyramid,  a cornercorner with one Cr(1)O4 tetrahedra, corners with three equivalent Cr(2)O4 tetrahedra,  an edgeedge with one Na(6)O5 square pyramid,  an edgeedge with one Na(7)O5 square pyramid, and  an edgeedge with one Mg(1)O4 tetrahedra. In the fourth Na site, Na(4) is bonded in a 4-coordinate geometry to one O(1), one O(5), one O(6), and one O(7) atom. In the fifth Na site, Na(5) is bonded in a 4-coordinate geometry to one O(1), one O(4), one O(5), and one O(7) atom. In the sixth Na site, Na(6) is bonded to one O(2), one O(3), one O(5), one O(6), and one O(8) atom to form distorted NaO5 square pyramids that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Cr(1)O4 tetrahedra, corners with two equivalent Cr(2)O4 tetrahedra, edges with two equivalent Na(7)O5 square pyramids,  an edgeedge with one Cr(1)O4 tetrahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. In the seventh Na site, Na(7) is bonded to one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form distorted NaO5 square pyramids that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Cr(2)O4 tetrahedra,  a cornercorner with one Na(3)O4 trigonal pyramid, edges with two equivalent Na(6)O5 square pyramids,  an edgeedge with one Cr(1)O4 tetrahedra,  an edgeedge with one Cr(2)O4 tetrahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. In the eighth Na site, Na(8) is bonded in a 4-coordinate geometry to one O(2), one O(5), one O(6), and one O(7) atom. Mg(1) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Na(6)O5 square pyramid,  a cornercorner with one Na(7)O5 square pyramid, corners with two equivalent Cr(2)O4 tetrahedra,  an edgeedge with one Cr(1)O4 tetrahedra, and  an edgeedge with one Na(3)O4 trigonal pyramid. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form CrO4 tetrahedra that share  a cornercorner with one Na(6)O5 square pyramid,  a cornercorner with one Na(3)O4 trigonal pyramid,  an edgeedge with one Na(6)O5 square pyramid,  an edgeedge with one Na(7)O5 square pyramid, and  an edgeedge with one Mg(1)O4 tetrahedra. In the second Cr site, Cr(2) is bonded to one O(3), one O(4), one O(7), and one O(8) atom to form CrO4 tetrahedra that share  a cornercorner with one Na(7)O5 square pyramid, corners with two equivalent Na(6)O5 square pyramids, corners with two equivalent Mg(1)O4 tetrahedra, corners with three equivalent Na(3)O4 trigonal pyramids, and  an edgeedge with one Na(7)O5 square pyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(3), one Na(4), one Na(5), one Mg(1), and one Cr(1) atom. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(6), one Na(7), one Na(8), and one Cr(1) atom to form ONa5Cr octahedra that share corners with two equivalent O(4)Na4MgCr octahedra and edges with two equivalent O(3)Na5Cr octahedra. The corner-sharing octahedral tilt angles range from 6-9°. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Na(3), one Na(6), one Na(7), and one Cr(2) atom to form distorted ONa5Cr octahedra that share edges with two equivalent O(4)Na4MgCr octahedra and edges with two equivalent O(2)Na5Cr octahedra. In the fourth O site, O(4) is bonded to one Na(2), one Na(3), one Na(5), one Na(7), one Mg(1), and one Cr(2) atom to form a mixture of distorted corner and edge-sharing ONa4MgCr octahedra. The corner-sharing octahedral tilt angles range from 6-9°. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Na(4), one Na(5), one Na(6), one Na(8), one Mg(1), and one Cr(1) atom. In the sixth O site, O(6) is bonded in a 7-coordinate geometry to one Na(1), one Na(2), one Na(4), one Na(6), one Na(7), one Na(8), and one Cr(1) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Na(4), one Na(5), one Na(8), one Mg(1), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(6), one Na(7), and one Cr(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na8MgCr2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.567
_cell_length_b   6.045
_cell_length_c   9.274
_cell_angle_alpha   69.064
_cell_angle_beta   79.751
_cell_angle_gamma   70.553
_symmetry_Int_Tables_number   1
_cell_volume   274.244
_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  0.765  0.000  0.424  1.0
  Na  Na1  1  0.742  0.418  0.587  1.0
  Na  Na2  1  0.261  0.332  0.773  1.0
  Na  Na3  1  0.413  0.882  0.061  1.0
  Na  Na4  1  0.760  0.236  0.984  1.0
  Na  Na5  1  0.251  0.521  0.422  1.0
  Na  Na6  1  0.249  0.909  0.587  1.0
  Na  Na7  1  0.765  0.562  0.218  1.0
  Mg  Mg8  1  0.192  0.600  0.965  1.0
  Cr  Cr9  1  0.269  0.192  0.242  1.0
  Cr  Cr10  1  0.711  0.801  0.758  1.0
  O  O11  1  0.140  0.263  0.042  1.0
  O  O12  1  0.018  0.255  0.400  1.0
  O  O13  1  0.966  0.652  0.628  1.0
  O  O14  1  0.479  0.598  0.802  1.0
  O  O15  1  0.381  0.492  0.159  1.0
  O  O16  1  0.473  0.856  0.334  1.0
  O  O17  1  0.845  0.847  0.937  1.0
  O  O18  1  0.526  0.116  0.635  1.0
[/CIF]
.