The structure described by MgDy2Nb2O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(2), one O(5), one O(6), and two equivalent O(7) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Nb(1)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and two equivalent O(3) atoms. In the second Dy site, Dy(2) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(7), one O(8), and two equivalent O(6) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(6), one O(8), and two equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 21°. In the second Nb site, Nb(2) is bonded to one O(1), one O(3), one O(7), one O(8), and two equivalent O(5) atoms to form distorted NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 28°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Dy(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1), one Dy(1), and one Nb(1) atom. In the third O site, O(3) is bonded to one Dy(2), two equivalent Dy(1), and one Nb(2) atom to form distorted ODy3Nb tetrahedra that share corners with two equivalent O(3)Dy3Nb tetrahedra and edges with two equivalent O(6)Dy3MgNb trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Dy(2) and two equivalent Nb(1) atoms. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Mg(1), one Dy(1), and two equivalent Nb(2) atoms. In the sixth O site, O(6) is bonded to one Mg(1), one Dy(1), two equivalent Dy(2), and one Nb(1) atom to form distorted ODy3MgNb trigonal pyramids that share corners with two equivalent O(6)Dy3MgNb trigonal pyramids and edges with two equivalent O(3)Dy3Nb tetrahedra. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1), one Dy(2), and one Nb(2) atom. In the eighth O site, O(8) is bonded in a T-shaped geometry to one Dy(2), one Nb(1), and one Nb(2) atom. is represented by the CIF file [CIF]
data_Dy2MgNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.972
_cell_length_b   7.512
_cell_length_c   7.408
_cell_angle_alpha   66.821
_cell_angle_beta   90.001
_cell_angle_gamma   74.707
_symmetry_Int_Tables_number   1
_cell_volume   194.649
_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
  Dy  Dy0  1  0.183  0.644  0.765  1.0
  Dy  Dy1  1  0.821  0.366  0.199  1.0
  Mg  Mg2  1  0.307  0.394  0.507  1.0
  Nb  Nb3  1  0.099  0.806  0.159  1.0
  Nb  Nb4  1  0.914  0.177  0.850  1.0
  O  O5  1  0.051  0.909  0.834  1.0
  O  O6  1  0.162  0.684  0.464  1.0
  O  O7  1  0.753  0.502  0.862  1.0
  O  O8  1  0.623  0.764  0.145  1.0
  O  O9  1  0.378  0.253  0.813  1.0
  O  O10  1  0.265  0.479  0.201  1.0
  O  O11  1  0.854  0.300  0.527  1.0
  O  O12  1  0.962  0.086  0.157  1.0
[/CIF]
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The structure described by MgDy2Nb2O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(2), one O(5), one O(6), and two equivalent O(7) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Nb(1)O6 octahedra, and edges with two equivalent Nb(2)O6 octahedra. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and two equivalent O(3) atoms. In the second Dy site, Dy(2) is bonded in a 6-coordinate geometry to one O(3), one O(4), one O(7), one O(8), and two equivalent O(6) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(6), one O(8), and two equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra,  an edgeedge with one Nb(2)O6 octahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 21°. In the second Nb site, Nb(2) is bonded to one O(1), one O(3), one O(7), one O(8), and two equivalent O(5) atoms to form distorted NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra,  an edgeedge with one Nb(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 28°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Dy(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1), one Dy(1), and one Nb(1) atom. In the third O site, O(3) is bonded to one Dy(2), two equivalent Dy(1), and one Nb(2) atom to form distorted ODy3Nb tetrahedra that share corners with two equivalent O(3)Dy3Nb tetrahedra and edges with two equivalent O(6)Dy3MgNb trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Dy(2) and two equivalent Nb(1) atoms. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Mg(1), one Dy(1), and two equivalent Nb(2) atoms. In the sixth O site, O(6) is bonded to one Mg(1), one Dy(1), two equivalent Dy(2), and one Nb(1) atom to form distorted ODy3MgNb trigonal pyramids that share corners with two equivalent O(6)Dy3MgNb trigonal pyramids and edges with two equivalent O(3)Dy3Nb tetrahedra. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1), one Dy(2), and one Nb(2) atom. In the eighth O site, O(8) is bonded in a T-shaped geometry to one Dy(2), one Nb(1), and one Nb(2) atom. is represented by the CIF file [CIF]
data_Dy2MgNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.972
_cell_length_b   7.512
_cell_length_c   7.408
_cell_angle_alpha   66.821
_cell_angle_beta   90.001
_cell_angle_gamma   74.707
_symmetry_Int_Tables_number   1
_cell_volume   194.649
_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
  Dy  Dy0  1  0.183  0.644  0.765  1.0
  Dy  Dy1  1  0.821  0.366  0.199  1.0
  Mg  Mg2  1  0.307  0.394  0.507  1.0
  Nb  Nb3  1  0.099  0.806  0.159  1.0
  Nb  Nb4  1  0.914  0.177  0.850  1.0
  O  O5  1  0.051  0.909  0.834  1.0
  O  O6  1  0.162  0.684  0.464  1.0
  O  O7  1  0.753  0.502  0.862  1.0
  O  O8  1  0.623  0.764  0.145  1.0
  O  O9  1  0.378  0.253  0.813  1.0
  O  O10  1  0.265  0.479  0.201  1.0
  O  O11  1  0.854  0.300  0.527  1.0
  O  O12  1  0.962  0.086  0.157  1.0
[/CIF]
.