The material structure described by MgPr2Nb2O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(7), and one O(8) atom. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. In the second Pr site, Pr(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted octahedral geometry to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. In the second Nb site, Nb(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Pr(2), and one Nb(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), one Pr(1), one Pr(2), and one Nb(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Pr(1), one Pr(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Pr(1), one Pr(2), and one Nb(1) atom. In the fifth O site, O(5) is bonded to one Pr(1), one Pr(2), one Nb(1), and one Nb(2) atom to form distorted corner-sharing OPr2Nb2 trigonal pyramids. In the sixth O site, O(6) is bonded to one Pr(1), one Pr(2), one Nb(1), and one Nb(2) atom to form distorted corner-sharing OPr2Nb2 tetrahedra. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Mg(1), one Pr(1), one Pr(2), one Nb(1), and one Nb(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Mg(1), one Pr(1), one Pr(2), one Nb(1), and one Nb(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Pr2MgNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.508
_cell_length_b   5.719
_cell_length_c   6.664
_cell_angle_alpha   114.410
_cell_angle_beta   102.019
_cell_angle_gamma   100.387
_symmetry_Int_Tables_number   1
_cell_volume   178.401
_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
  Pr  Pr0  1  0.847  0.116  0.723  1.0
  Pr  Pr1  1  0.120  0.829  0.225  1.0
  Mg  Mg2  1  0.416  0.275  0.885  1.0
  Nb  Nb3  1  0.349  0.594  0.636  1.0
  Nb  Nb4  1  0.646  0.382  0.354  1.0
  O  O5  1  0.339  0.143  0.113  1.0
  O  O6  1  0.776  0.433  0.091  1.0
  O  O7  1  0.659  0.828  0.870  1.0
  O  O8  1  0.204  0.514  0.893  1.0
  O  O9  1  0.498  0.711  0.408  1.0
  O  O10  1  0.957  0.251  0.427  1.0
  O  O11  1  0.487  0.252  0.584  1.0
  O  O12  1  0.102  0.828  0.597  1.0
[/CIF]
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The material structure described by MgPr2Nb2O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(7), and one O(8) atom. There are two inequivalent Pr sites. In the first Pr site, Pr(1) is bonded in a 7-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. In the second Pr site, Pr(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a distorted octahedral geometry to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. In the second Nb site, Nb(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Pr(2), and one Nb(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), one Pr(1), one Pr(2), and one Nb(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Pr(1), one Pr(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), one Pr(1), one Pr(2), and one Nb(1) atom. In the fifth O site, O(5) is bonded to one Pr(1), one Pr(2), one Nb(1), and one Nb(2) atom to form distorted corner-sharing OPr2Nb2 trigonal pyramids. In the sixth O site, O(6) is bonded to one Pr(1), one Pr(2), one Nb(1), and one Nb(2) atom to form distorted corner-sharing OPr2Nb2 tetrahedra. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Mg(1), one Pr(1), one Pr(2), one Nb(1), and one Nb(2) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one Mg(1), one Pr(1), one Pr(2), one Nb(1), and one Nb(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Pr2MgNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.508
_cell_length_b   5.719
_cell_length_c   6.664
_cell_angle_alpha   114.410
_cell_angle_beta   102.019
_cell_angle_gamma   100.387
_symmetry_Int_Tables_number   1
_cell_volume   178.401
_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
  Pr  Pr0  1  0.847  0.116  0.723  1.0
  Pr  Pr1  1  0.120  0.829  0.225  1.0
  Mg  Mg2  1  0.416  0.275  0.885  1.0
  Nb  Nb3  1  0.349  0.594  0.636  1.0
  Nb  Nb4  1  0.646  0.382  0.354  1.0
  O  O5  1  0.339  0.143  0.113  1.0
  O  O6  1  0.776  0.433  0.091  1.0
  O  O7  1  0.659  0.828  0.870  1.0
  O  O8  1  0.204  0.514  0.893  1.0
  O  O9  1  0.498  0.711  0.408  1.0
  O  O10  1  0.957  0.251  0.427  1.0
  O  O11  1  0.487  0.252  0.584  1.0
  O  O12  1  0.102  0.828  0.597  1.0
[/CIF]
.