The material described by MgNb2O5 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(5) atoms to form MgO5 trigonal bipyramids that share corners with four equivalent Mg(1)O5 trigonal bipyramids, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Nb(1)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(5) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-38°. In the second Nb site, Nb(2) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-40°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1) and two equivalent Nb(2) atoms. In the third O site, O(3) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Nb(2) atoms. In the fifth O site, O(5) is bonded to two equivalent Mg(1), one Nb(2), and two equivalent Nb(1) atoms to form distorted corner-sharing OMg2Nb3 trigonal bipyramids. is represented by the CIF card [CIF]
data_MgNb2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.888
_cell_length_b   4.144
_cell_length_c   7.196
_cell_angle_alpha   90.228
_cell_angle_beta   105.652
_cell_angle_gamma   90.006
_symmetry_Int_Tables_number   1
_cell_volume   111.630
_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
  Mg  Mg0  1  0.703  0.500  0.408  1.0
  Nb  Nb1  1  0.136  1.000  0.272  1.0
  Nb  Nb2  1  0.860  0.004  0.720  1.0
  O  O3  1  0.147  0.500  0.295  1.0
  O  O4  1  0.847  0.505  0.695  1.0
  O  O5  1  0.997  0.003  0.995  1.0
  O  O6  1  0.309  0.005  0.618  1.0
  O  O7  1  0.684  1.000  0.368  1.0
[/CIF]
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The material described by MgNb2O5 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(5) atoms to form MgO5 trigonal bipyramids that share corners with four equivalent Mg(1)O5 trigonal bipyramids, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Nb(1)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(5) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with four equivalent Nb(1)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and edges with four equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-38°. In the second Nb site, Nb(2) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-40°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1) and two equivalent Nb(2) atoms. In the third O site, O(3) is bonded in a linear geometry to one Nb(1) and one Nb(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Nb(1) and two equivalent Nb(2) atoms. In the fifth O site, O(5) is bonded to two equivalent Mg(1), one Nb(2), and two equivalent Nb(1) atoms to form distorted corner-sharing OMg2Nb3 trigonal bipyramids. is represented by the CIF card [CIF]
data_MgNb2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.888
_cell_length_b   4.144
_cell_length_c   7.196
_cell_angle_alpha   90.228
_cell_angle_beta   105.652
_cell_angle_gamma   90.006
_symmetry_Int_Tables_number   1
_cell_volume   111.630
_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
  Mg  Mg0  1  0.703  0.500  0.408  1.0
  Nb  Nb1  1  0.136  1.000  0.272  1.0
  Nb  Nb2  1  0.860  0.004  0.720  1.0
  O  O3  1  0.147  0.500  0.295  1.0
  O  O4  1  0.847  0.505  0.695  1.0
  O  O5  1  0.997  0.003  0.995  1.0
  O  O6  1  0.309  0.005  0.618  1.0
  O  O7  1  0.684  1.000  0.368  1.0
[/CIF]
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