The material structure described by MgTb2Nb2O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted trigonal pyramidal geometry to one O(1), one O(2), one O(5), and one O(7) atom. There are two inequivalent Tb sites. In the first Tb site, Tb(1) 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. In the second Tb site, Tb(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 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), 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 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), and one Nb(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Tb(1), one Tb(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Tb(1), one Tb(2), one Nb(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), one Nb(1), and one Nb(2) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Tb(1), one Tb(2), one Nb(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Tb(1), one Tb(2), and one Nb(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Tb(1), one Tb(2), and one Nb(2) atom. is represented by the CIF card [CIF]
data_Tb2MgNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.533
_cell_length_b   5.428
_cell_length_c   5.521
_cell_angle_alpha   84.519
_cell_angle_beta   91.155
_cell_angle_gamma   95.209
_symmetry_Int_Tables_number   1
_cell_volume   164.361
_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
  Tb  Tb0  1  0.232  0.997  0.729  1.0
  Tb  Tb1  1  0.739  0.001  0.235  1.0
  Mg  Mg2  1  0.889  0.500  0.377  1.0
  Nb  Nb3  1  0.373  0.493  0.238  1.0
  Nb  Nb4  1  0.744  0.506  0.862  1.0
  O  O5  1  0.017  0.696  0.070  1.0
  O  O6  1  0.104  0.239  0.383  1.0
  O  O7  1  0.405  0.774  0.426  1.0
  O  O8  1  0.449  0.255  0.989  1.0
  O  O9  1  0.583  0.302  0.504  1.0
  O  O10  1  0.505  0.754  0.948  1.0
  O  O11  1  0.891  0.760  0.592  1.0
  O  O12  1  0.928  0.223  0.898  1.0
[/CIF]
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The material structure described by MgTb2Nb2O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted trigonal pyramidal geometry to one O(1), one O(2), one O(5), and one O(7) atom. There are two inequivalent Tb sites. In the first Tb site, Tb(1) 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. In the second Tb site, Tb(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 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), 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 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), and one Nb(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Tb(1), one Tb(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Tb(1), one Tb(2), one Nb(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Tb(1), one Tb(2), one Nb(1), and one Nb(2) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Tb(1), one Tb(2), one Nb(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal pyramidal geometry to one Mg(1), one Tb(1), one Tb(2), and one Nb(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Tb(1), one Tb(2), and one Nb(2) atom. is represented by the CIF card [CIF]
data_Tb2MgNb2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.533
_cell_length_b   5.428
_cell_length_c   5.521
_cell_angle_alpha   84.519
_cell_angle_beta   91.155
_cell_angle_gamma   95.209
_symmetry_Int_Tables_number   1
_cell_volume   164.361
_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
  Tb  Tb0  1  0.232  0.997  0.729  1.0
  Tb  Tb1  1  0.739  0.001  0.235  1.0
  Mg  Mg2  1  0.889  0.500  0.377  1.0
  Nb  Nb3  1  0.373  0.493  0.238  1.0
  Nb  Nb4  1  0.744  0.506  0.862  1.0
  O  O5  1  0.017  0.696  0.070  1.0
  O  O6  1  0.104  0.239  0.383  1.0
  O  O7  1  0.405  0.774  0.426  1.0
  O  O8  1  0.449  0.255  0.989  1.0
  O  O9  1  0.583  0.302  0.504  1.0
  O  O10  1  0.505  0.754  0.948  1.0
  O  O11  1  0.891  0.760  0.592  1.0
  O  O12  1  0.928  0.223  0.898  1.0
[/CIF]
.