The material described by MgY2Nb2O8 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form MgO4 tetrahedra that share corners with two equivalent Y(2)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and  an edgeedge with one Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-68°. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. In the second Y site, Y(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted YO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles are 35°. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NbO6 octahedra that share edges with two equivalent Y(2)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. In the second Nb site, Nb(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share corners with two equivalent Y(2)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Y(2)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 35°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), one Nb(1), and one Nb(2) atom to form a mixture of distorted edge and corner-sharing OY2Nb2 trigonal pyramids. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Y(2), and one Nb(2) atom. In the third O site, O(3) is bonded to one Y(1), one Y(2), one Nb(1), and one Nb(2) atom to form a mixture of distorted edge and corner-sharing OY2Nb2 trigonal pyramids. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Mg(1), one Y(1), and one Nb(1) atom. is represented by the CIF card [CIF]
data_Y2MgNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.255
_cell_length_b   5.316
_cell_length_c   8.013
_cell_angle_alpha   105.264
_cell_angle_beta   104.992
_cell_angle_gamma   102.046
_symmetry_Int_Tables_number   1
_cell_volume   199.214
_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
  Y  Y0  1  0.597  0.847  0.194  1.0
  Y  Y1  1  0.424  0.174  0.848  1.0
  Mg  Mg2  1  0.269  0.519  0.538  1.0
  Nb  Nb3  1  0.074  0.324  0.148  1.0
  Nb  Nb4  1  0.929  0.679  0.859  1.0
  O  O5  1  0.800  0.529  0.079  1.0
  O  O6  1  0.280  0.050  0.079  1.0
  O  O7  1  0.118  0.766  0.687  1.0
  O  O8  1  0.569  0.420  0.687  1.0
  O  O9  1  0.210  0.482  0.943  1.0
  O  O10  1  0.733  0.961  0.943  1.0
  O  O11  1  0.967  0.203  0.347  1.0
  O  O12  1  0.380  0.644  0.347  1.0
[/CIF]
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The material described by MgY2Nb2O8 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(2) and two equivalent O(4) atoms to form MgO4 tetrahedra that share corners with two equivalent Y(2)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and  an edgeedge with one Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-68°. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. In the second Y site, Y(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted YO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Nb(1)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles are 35°. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NbO6 octahedra that share edges with two equivalent Y(2)O6 octahedra, edges with two equivalent Nb(2)O6 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. In the second Nb site, Nb(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share corners with two equivalent Y(2)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, edges with two equivalent Y(2)O6 octahedra, and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles are 35°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Y(1), one Y(2), one Nb(1), and one Nb(2) atom to form a mixture of distorted edge and corner-sharing OY2Nb2 trigonal pyramids. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Y(2), and one Nb(2) atom. In the third O site, O(3) is bonded to one Y(1), one Y(2), one Nb(1), and one Nb(2) atom to form a mixture of distorted edge and corner-sharing OY2Nb2 trigonal pyramids. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Mg(1), one Y(1), and one Nb(1) atom. is represented by the CIF card [CIF]
data_Y2MgNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.255
_cell_length_b   5.316
_cell_length_c   8.013
_cell_angle_alpha   105.264
_cell_angle_beta   104.992
_cell_angle_gamma   102.046
_symmetry_Int_Tables_number   1
_cell_volume   199.214
_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
  Y  Y0  1  0.597  0.847  0.194  1.0
  Y  Y1  1  0.424  0.174  0.848  1.0
  Mg  Mg2  1  0.269  0.519  0.538  1.0
  Nb  Nb3  1  0.074  0.324  0.148  1.0
  Nb  Nb4  1  0.929  0.679  0.859  1.0
  O  O5  1  0.800  0.529  0.079  1.0
  O  O6  1  0.280  0.050  0.079  1.0
  O  O7  1  0.118  0.766  0.687  1.0
  O  O8  1  0.569  0.420  0.687  1.0
  O  O9  1  0.210  0.482  0.943  1.0
  O  O10  1  0.733  0.961  0.943  1.0
  O  O11  1  0.967  0.203  0.347  1.0
  O  O12  1  0.380  0.644  0.347  1.0
[/CIF]
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