The material described by Ba3MgNb2CoO9 crystallizes in the triclinic P1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one O(1), one O(3), one O(4), one O(6), one O(7), one O(9), two equivalent O(2), two equivalent O(5), and two equivalent O(8) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(1)O12 cuboctahedra, faces with two equivalent Nb(2)O6 octahedra, faces with three equivalent Nb(1)O6 octahedra, and faces with three equivalent Co(1)O6 octahedra. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one Mg(1), one O(1), one O(2), one O(5), one O(6), one O(8), one O(9), and two equivalent O(4) atoms. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to one Mg(1), one O(2), one O(3), one O(4), one O(5), one O(7), one O(8), and two equivalent O(6) atoms. Mg(1) is bonded in a rectangular see-saw-like geometry to one Ba(2), one Ba(3), one O(1), one O(3), one O(7), and one O(9) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(8), and one O(9) atom to form NbO6 octahedra that share corners with three equivalent Nb(2)O6 octahedra, corners with three equivalent Co(1)O6 octahedra, and faces with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the second Nb site, Nb(2) is bonded to one O(1), one O(3), one O(4), one O(6), one O(7), and one O(9) atom to form NbO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Co(1)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-8°. Co(1) is bonded to one O(2), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form distorted CoO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Nb(2)O6 octahedra, and faces with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-6°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Nb(1), and one Co(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Mg(1), one Nb(2), and one Co(1) atom. In the fourth O site, O(4) is bonded to one Ba(1), one Ba(3), two equivalent Ba(2), one Nb(1), and one Nb(2) atom to form distorted corner-sharing OBa4Nb2 octahedra. The corner-sharing octahedral tilt angles are 22°. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Nb(1), and one Co(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Nb(2), and one Co(1) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Mg(1), one Nb(2), and one Co(1) atom. In the eighth O site, O(8) is bonded in a 1-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Nb(1), and one Co(1) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Ba(1), one Ba(2), one Mg(1), one Nb(1), and one Nb(2) atom. is represented by the CIF card [CIF]
data_Ba3MgNb2CoO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.192
_cell_length_b   5.917
_cell_length_c   7.491
_cell_angle_alpha   90.061
_cell_angle_beta   84.970
_cell_angle_gamma   118.483
_symmetry_Int_Tables_number   1
_cell_volume   240.036
_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
  Ba  Ba0  1  0.669  0.336  0.344  1.0
  Ba  Ba1  1  0.074  0.038  0.054  1.0
  Ba  Ba2  1  0.228  0.616  0.631  1.0
  Mg  Mg3  1  0.676  0.837  0.820  1.0
  Nb  Nb4  1  0.338  0.670  0.177  1.0
  Nb  Nb5  1  0.657  0.328  0.830  1.0
  Co  Co6  1  0.001  0.001  0.490  1.0
  O  O7  1  0.509  0.520  0.992  1.0
  O  O8  1  0.173  0.344  0.325  1.0
  O  O9  1  0.826  0.665  0.674  1.0
  O  O10  1  1.000  0.500  0.003  1.0
  O  O11  1  0.173  0.831  0.324  1.0
  O  O12  1  0.378  0.187  0.691  1.0
  O  O13  1  0.829  0.159  0.677  1.0
  O  O14  1  0.628  0.815  0.308  1.0
  O  O15  1  0.509  0.988  0.992  1.0
[/CIF]
.
The material described by Ba3MgNb2CoO9 crystallizes in the triclinic P1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one O(1), one O(3), one O(4), one O(6), one O(7), one O(9), two equivalent O(2), two equivalent O(5), and two equivalent O(8) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(1)O12 cuboctahedra, faces with two equivalent Nb(2)O6 octahedra, faces with three equivalent Nb(1)O6 octahedra, and faces with three equivalent Co(1)O6 octahedra. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one Mg(1), one O(1), one O(2), one O(5), one O(6), one O(8), one O(9), and two equivalent O(4) atoms. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to one Mg(1), one O(2), one O(3), one O(4), one O(5), one O(7), one O(8), and two equivalent O(6) atoms. Mg(1) is bonded in a rectangular see-saw-like geometry to one Ba(2), one Ba(3), one O(1), one O(3), one O(7), and one O(9) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(8), and one O(9) atom to form NbO6 octahedra that share corners with three equivalent Nb(2)O6 octahedra, corners with three equivalent Co(1)O6 octahedra, and faces with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the second Nb site, Nb(2) is bonded to one O(1), one O(3), one O(4), one O(6), one O(7), and one O(9) atom to form NbO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Co(1)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-8°. Co(1) is bonded to one O(2), one O(3), one O(5), one O(6), one O(7), and one O(8) atom to form distorted CoO6 octahedra that share corners with three equivalent Nb(1)O6 octahedra, corners with three equivalent Nb(2)O6 octahedra, and faces with three equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-6°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Nb(1), and one Co(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Mg(1), one Nb(2), and one Co(1) atom. In the fourth O site, O(4) is bonded to one Ba(1), one Ba(3), two equivalent Ba(2), one Nb(1), and one Nb(2) atom to form distorted corner-sharing OBa4Nb2 octahedra. The corner-sharing octahedral tilt angles are 22°. In the fifth O site, O(5) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Nb(1), and one Co(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Nb(2), and one Co(1) atom. In the seventh O site, O(7) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Mg(1), one Nb(2), and one Co(1) atom. In the eighth O site, O(8) is bonded in a 1-coordinate geometry to one Ba(2), one Ba(3), two equivalent Ba(1), one Nb(1), and one Co(1) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Ba(1), one Ba(2), one Mg(1), one Nb(1), and one Nb(2) atom. is represented by the CIF card [CIF]
data_Ba3MgNb2CoO9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.192
_cell_length_b   5.917
_cell_length_c   7.491
_cell_angle_alpha   90.061
_cell_angle_beta   84.970
_cell_angle_gamma   118.483
_symmetry_Int_Tables_number   1
_cell_volume   240.036
_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
  Ba  Ba0  1  0.669  0.336  0.344  1.0
  Ba  Ba1  1  0.074  0.038  0.054  1.0
  Ba  Ba2  1  0.228  0.616  0.631  1.0
  Mg  Mg3  1  0.676  0.837  0.820  1.0
  Nb  Nb4  1  0.338  0.670  0.177  1.0
  Nb  Nb5  1  0.657  0.328  0.830  1.0
  Co  Co6  1  0.001  0.001  0.490  1.0
  O  O7  1  0.509  0.520  0.992  1.0
  O  O8  1  0.173  0.344  0.325  1.0
  O  O9  1  0.826  0.665  0.674  1.0
  O  O10  1  1.000  0.500  0.003  1.0
  O  O11  1  0.173  0.831  0.324  1.0
  O  O12  1  0.378  0.187  0.691  1.0
  O  O13  1  0.829  0.159  0.677  1.0
  O  O14  1  0.628  0.815  0.308  1.0
  O  O15  1  0.509  0.988  0.992  1.0
[/CIF]
.