The compound described by Bi2MgO4 is Spinel-like structured and crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3) and three equivalent O(4) atoms to form MgO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra and corners with nine equivalent Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-57°. In the second Mg site, Mg(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form MgO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Bi(1)O4 tetrahedra, and edges with six equivalent Bi(2)O6 octahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(2) and three equivalent O(1) atoms to form BiO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra and corners with nine equivalent Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-66°. In the second Bi site, Bi(2) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form BiO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Bi(1)O4 tetrahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with four equivalent Bi(2)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), one Bi(1), and two equivalent Bi(2) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Bi(1) and three equivalent Bi(2) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1) and three equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mg(2), and two equivalent Bi(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg(BiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.734
_cell_length_b   6.734
_cell_length_c   6.734
_cell_angle_alpha   61.798
_cell_angle_beta   61.798
_cell_angle_gamma   61.798
_symmetry_Int_Tables_number   1
_cell_volume   224.655
_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  0.999  0.999  0.999  1.0
  Mg  Mg1  1  0.375  0.375  0.375  1.0
  Bi  Bi2  1  0.758  0.758  0.758  1.0
  Bi  Bi3  1  0.374  0.881  0.374  1.0
  Bi  Bi4  1  0.881  0.374  0.374  1.0
  Bi  Bi5  1  0.374  0.374  0.881  1.0
  O  O6  1  0.597  0.597  0.162  1.0
  O  O7  1  0.162  0.597  0.597  1.0
  O  O8  1  0.597  0.162  0.597  1.0
  O  O9  1  0.625  0.625  0.625  1.0
  O  O10  1  0.125  0.125  0.125  1.0
  O  O11  1  0.132  0.618  0.132  1.0
  O  O12  1  0.618  0.132  0.132  1.0
  O  O13  1  0.132  0.132  0.618  1.0
[/CIF]
.
The compound described by Bi2MgO4 is Spinel-like structured and crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3) and three equivalent O(4) atoms to form MgO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra and corners with nine equivalent Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-57°. In the second Mg site, Mg(2) is bonded to three equivalent O(1) and three equivalent O(4) atoms to form MgO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Bi(1)O4 tetrahedra, and edges with six equivalent Bi(2)O6 octahedra. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(2) and three equivalent O(1) atoms to form BiO4 tetrahedra that share corners with three equivalent Mg(2)O6 octahedra and corners with nine equivalent Bi(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-66°. In the second Bi site, Bi(2) is bonded to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms to form BiO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Bi(1)O4 tetrahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with four equivalent Bi(2)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), one Bi(1), and two equivalent Bi(2) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Bi(1) and three equivalent Bi(2) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1) and three equivalent Bi(2) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Mg(2), and two equivalent Bi(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg(BiO2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.734
_cell_length_b   6.734
_cell_length_c   6.734
_cell_angle_alpha   61.798
_cell_angle_beta   61.798
_cell_angle_gamma   61.798
_symmetry_Int_Tables_number   1
_cell_volume   224.655
_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  0.999  0.999  0.999  1.0
  Mg  Mg1  1  0.375  0.375  0.375  1.0
  Bi  Bi2  1  0.758  0.758  0.758  1.0
  Bi  Bi3  1  0.374  0.881  0.374  1.0
  Bi  Bi4  1  0.881  0.374  0.374  1.0
  Bi  Bi5  1  0.374  0.374  0.881  1.0
  O  O6  1  0.597  0.597  0.162  1.0
  O  O7  1  0.162  0.597  0.597  1.0
  O  O8  1  0.597  0.162  0.597  1.0
  O  O9  1  0.625  0.625  0.625  1.0
  O  O10  1  0.125  0.125  0.125  1.0
  O  O11  1  0.132  0.618  0.132  1.0
  O  O12  1  0.618  0.132  0.132  1.0
  O  O13  1  0.132  0.132  0.618  1.0
[/CIF]
.