The compound described by Mg6CeNb crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ce(1), and two equivalent Nb(1) atoms. In the second Mg site, Mg(2) is bonded in a 12-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ce(1) atoms. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ce(1), and two equivalent Nb(1) atoms to form distorted MgCe2Mg8Nb2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with ten equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, and faces with four equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Nb(1) atoms to form distorted MgMg10Nb2 cuboctahedra that share corners with six equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with eight equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra, edges with four equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, and faces with four equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra. Ce(1) is bonded in a 2-coordinate geometry to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Nb(1) atoms. Nb(1) is bonded in a 2-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ce(1) atoms. is represented by the CIF card [CIF]
data_CeMg6Nb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.646
_cell_length_b   6.646
_cell_length_c   4.886
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   121.990
_symmetry_Int_Tables_number   1
_cell_volume   183.007
_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
  Ce  Ce0  1  0.200  0.300  0.250  1.0
  Mg  Mg1  1  0.186  0.830  0.250  1.0
  Mg  Mg2  1  0.670  0.314  0.250  1.0
  Mg  Mg3  1  0.666  0.834  0.250  1.0
  Mg  Mg4  1  0.329  0.683  0.750  1.0
  Mg  Mg5  1  0.817  0.171  0.750  1.0
  Mg  Mg6  1  0.828  0.672  0.750  1.0
  Nb  Nb7  1  0.304  0.196  0.750  1.0
[/CIF]
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The compound described by Mg6CeNb crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ce(1), and two equivalent Nb(1) atoms. In the second Mg site, Mg(2) is bonded in a 12-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ce(1) atoms. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ce(1), and two equivalent Nb(1) atoms to form distorted MgCe2Mg8Nb2 cuboctahedra that share corners with four equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with ten equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra, edges with two equivalent Mg(4)Mg10Nb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, and faces with four equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Nb(1) atoms to form distorted MgMg10Nb2 cuboctahedra that share corners with six equivalent Mg(4)Mg10Nb2 cuboctahedra, corners with eight equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra, edges with four equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra, faces with two equivalent Mg(4)Mg10Nb2 cuboctahedra, and faces with four equivalent Mg(3)Ce2Mg8Nb2 cuboctahedra. Ce(1) is bonded in a 2-coordinate geometry to two equivalent Mg(2), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Nb(1) atoms. Nb(1) is bonded in a 2-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), four equivalent Mg(3), and two equivalent Ce(1) atoms. is represented by the CIF card [CIF]
data_CeMg6Nb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.646
_cell_length_b   6.646
_cell_length_c   4.886
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   121.990
_symmetry_Int_Tables_number   1
_cell_volume   183.007
_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
  Ce  Ce0  1  0.200  0.300  0.250  1.0
  Mg  Mg1  1  0.186  0.830  0.250  1.0
  Mg  Mg2  1  0.670  0.314  0.250  1.0
  Mg  Mg3  1  0.666  0.834  0.250  1.0
  Mg  Mg4  1  0.329  0.683  0.750  1.0
  Mg  Mg5  1  0.817  0.171  0.750  1.0
  Mg  Mg6  1  0.828  0.672  0.750  1.0
  Nb  Nb7  1  0.304  0.196  0.750  1.0
[/CIF]
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