The material described by Mg2TiNb2O8 crystallizes in the monoclinic C2/c space group. Mg(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(4) atoms. Ti(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TiO6 octahedra that share corners with eight equivalent Nb(1)O6 octahedra and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-52°. Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with four equivalent Ti(1)O6 octahedra and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-52°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ti(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ti(1) and one Nb(1) atom. In the third O site, O(3) is bonded to three equivalent Mg(1) and two equivalent Nb(1) atoms to form distorted OMg3Nb2 trigonal bipyramids that share corners with two equivalent O(3)Mg3Nb2 trigonal bipyramids, corners with three equivalent O(4)Mg3Nb trigonal pyramids, edges with three equivalent O(3)Mg3Nb2 trigonal bipyramids, and edges with four equivalent O(4)Mg3Nb trigonal pyramids. In the fourth O site, O(4) is bonded to three equivalent Mg(1) and one Nb(1) atom to form OMg3Nb trigonal pyramids that share corners with three equivalent O(3)Mg3Nb2 trigonal bipyramids, corners with four equivalent O(4)Mg3Nb trigonal pyramids, edges with four equivalent O(3)Mg3Nb2 trigonal bipyramids, and  an edgeedge with one O(4)Mg3Nb trigonal pyramid. is represented by the CIF file [CIF]
data_Mg2TiNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.992
_cell_length_b   9.992
_cell_length_c   5.228
_cell_angle_alpha   89.775
_cell_angle_beta   89.775
_cell_angle_gamma   34.744
_symmetry_Int_Tables_number   1
_cell_volume   297.454
_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  0.865  0.590  0.756  1.0
  Mg  Mg1  1  0.410  0.135  0.744  1.0
  Mg  Mg2  1  0.135  0.410  0.244  1.0
  Mg  Mg3  1  0.590  0.865  0.256  1.0
  Ti  Ti4  1  0.630  0.370  0.750  1.0
  Ti  Ti5  1  0.370  0.630  0.250  1.0
  Nb  Nb6  1  0.025  0.743  0.740  1.0
  Nb  Nb7  1  0.257  0.975  0.760  1.0
  Nb  Nb8  1  0.975  0.257  0.260  1.0
  Nb  Nb9  1  0.743  0.025  0.240  1.0
  O  O10  1  0.069  0.800  0.096  1.0
  O  O11  1  0.200  0.931  0.404  1.0
  O  O12  1  0.931  0.200  0.904  1.0
  O  O13  1  0.800  0.069  0.596  1.0
  O  O14  1  0.316  0.574  0.581  1.0
  O  O15  1  0.426  0.684  0.919  1.0
  O  O16  1  0.684  0.426  0.419  1.0
  O  O17  1  0.574  0.316  0.081  1.0
  O  O18  1  0.913  0.716  0.437  1.0
  O  O19  1  0.284  0.087  0.063  1.0
  O  O20  1  0.456  0.163  0.373  1.0
  O  O21  1  0.837  0.544  0.127  1.0
  O  O22  1  0.544  0.837  0.627  1.0
  O  O23  1  0.163  0.456  0.873  1.0
  O  O24  1  0.716  0.913  0.937  1.0
  O  O25  1  0.087  0.284  0.563  1.0
[/CIF]
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The material described by Mg2TiNb2O8 crystallizes in the monoclinic C2/c space group. Mg(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(4) atoms. Ti(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TiO6 octahedra that share corners with eight equivalent Nb(1)O6 octahedra and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-52°. Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form NbO6 octahedra that share corners with four equivalent Ti(1)O6 octahedra and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-52°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ti(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ti(1) and one Nb(1) atom. In the third O site, O(3) is bonded to three equivalent Mg(1) and two equivalent Nb(1) atoms to form distorted OMg3Nb2 trigonal bipyramids that share corners with two equivalent O(3)Mg3Nb2 trigonal bipyramids, corners with three equivalent O(4)Mg3Nb trigonal pyramids, edges with three equivalent O(3)Mg3Nb2 trigonal bipyramids, and edges with four equivalent O(4)Mg3Nb trigonal pyramids. In the fourth O site, O(4) is bonded to three equivalent Mg(1) and one Nb(1) atom to form OMg3Nb trigonal pyramids that share corners with three equivalent O(3)Mg3Nb2 trigonal bipyramids, corners with four equivalent O(4)Mg3Nb trigonal pyramids, edges with four equivalent O(3)Mg3Nb2 trigonal bipyramids, and  an edgeedge with one O(4)Mg3Nb trigonal pyramid. is represented by the CIF file [CIF]
data_Mg2TiNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.992
_cell_length_b   9.992
_cell_length_c   5.228
_cell_angle_alpha   89.775
_cell_angle_beta   89.775
_cell_angle_gamma   34.744
_symmetry_Int_Tables_number   1
_cell_volume   297.454
_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  0.865  0.590  0.756  1.0
  Mg  Mg1  1  0.410  0.135  0.744  1.0
  Mg  Mg2  1  0.135  0.410  0.244  1.0
  Mg  Mg3  1  0.590  0.865  0.256  1.0
  Ti  Ti4  1  0.630  0.370  0.750  1.0
  Ti  Ti5  1  0.370  0.630  0.250  1.0
  Nb  Nb6  1  0.025  0.743  0.740  1.0
  Nb  Nb7  1  0.257  0.975  0.760  1.0
  Nb  Nb8  1  0.975  0.257  0.260  1.0
  Nb  Nb9  1  0.743  0.025  0.240  1.0
  O  O10  1  0.069  0.800  0.096  1.0
  O  O11  1  0.200  0.931  0.404  1.0
  O  O12  1  0.931  0.200  0.904  1.0
  O  O13  1  0.800  0.069  0.596  1.0
  O  O14  1  0.316  0.574  0.581  1.0
  O  O15  1  0.426  0.684  0.919  1.0
  O  O16  1  0.684  0.426  0.419  1.0
  O  O17  1  0.574  0.316  0.081  1.0
  O  O18  1  0.913  0.716  0.437  1.0
  O  O19  1  0.284  0.087  0.063  1.0
  O  O20  1  0.456  0.163  0.373  1.0
  O  O21  1  0.837  0.544  0.127  1.0
  O  O22  1  0.544  0.837  0.627  1.0
  O  O23  1  0.163  0.456  0.873  1.0
  O  O24  1  0.716  0.913  0.937  1.0
  O  O25  1  0.087  0.284  0.563  1.0
[/CIF]
.