The material described by RbMg6Nb crystallizes in the tetragonal P4/mmm space group. Rb(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form RbMg12 cuboctahedra that share corners with four equivalent Rb(1)Mg12 cuboctahedra, corners with eight equivalent Nb(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra, faces with two equivalent Rb(1)Mg12 cuboctahedra, faces with four equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra, and faces with four equivalent Nb(1)Mg12 cuboctahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Rb(1), eight equivalent Mg(2), and two equivalent Nb(1) atoms to form distorted MgRb2Mg8Nb2 cuboctahedra that share corners with twelve equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra, edges with four equivalent Rb(1)Mg12 cuboctahedra, edges with four equivalent Nb(1)Mg12 cuboctahedra, faces with two equivalent Rb(1)Mg12 cuboctahedra, faces with two equivalent Nb(1)Mg12 cuboctahedra, and faces with six equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Rb(1), two equivalent Mg(2), four equivalent Mg(1), and two equivalent Nb(1) atoms. Nb(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form NbMg12 cuboctahedra that share corners with four equivalent Nb(1)Mg12 cuboctahedra, corners with eight equivalent Rb(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra, faces with two equivalent Nb(1)Mg12 cuboctahedra, faces with four equivalent Rb(1)Mg12 cuboctahedra, and faces with four equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_RbMg6Nb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.782
_cell_length_b   6.782
_cell_length_c   4.492
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   206.593
_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
  Rb  Rb0  1  0.000  0.000  0.500  1.0
  Mg  Mg1  1  0.000  0.500  0.500  1.0
  Mg  Mg2  1  0.500  0.000  0.500  1.0
  Mg  Mg3  1  0.714  0.286  0.000  1.0
  Mg  Mg4  1  0.286  0.714  0.000  1.0
  Mg  Mg5  1  0.714  0.714  0.000  1.0
  Mg  Mg6  1  0.286  0.286  0.000  1.0
  Nb  Nb7  1  0.500  0.500  0.500  1.0
[/CIF]
.
The material described by RbMg6Nb crystallizes in the tetragonal P4/mmm space group. Rb(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form RbMg12 cuboctahedra that share corners with four equivalent Rb(1)Mg12 cuboctahedra, corners with eight equivalent Nb(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra, faces with two equivalent Rb(1)Mg12 cuboctahedra, faces with four equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra, and faces with four equivalent Nb(1)Mg12 cuboctahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Rb(1), eight equivalent Mg(2), and two equivalent Nb(1) atoms to form distorted MgRb2Mg8Nb2 cuboctahedra that share corners with twelve equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra, edges with four equivalent Rb(1)Mg12 cuboctahedra, edges with four equivalent Nb(1)Mg12 cuboctahedra, faces with two equivalent Rb(1)Mg12 cuboctahedra, faces with two equivalent Nb(1)Mg12 cuboctahedra, and faces with six equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Rb(1), two equivalent Mg(2), four equivalent Mg(1), and two equivalent Nb(1) atoms. Nb(1) is bonded to four equivalent Mg(1) and eight equivalent Mg(2) atoms to form NbMg12 cuboctahedra that share corners with four equivalent Nb(1)Mg12 cuboctahedra, corners with eight equivalent Rb(1)Mg12 cuboctahedra, edges with eight equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra, faces with two equivalent Nb(1)Mg12 cuboctahedra, faces with four equivalent Rb(1)Mg12 cuboctahedra, and faces with four equivalent Mg(1)Rb2Mg8Nb2 cuboctahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_RbMg6Nb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.782
_cell_length_b   6.782
_cell_length_c   4.492
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   206.593
_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
  Rb  Rb0  1  0.000  0.000  0.500  1.0
  Mg  Mg1  1  0.000  0.500  0.500  1.0
  Mg  Mg2  1  0.500  0.000  0.500  1.0
  Mg  Mg3  1  0.714  0.286  0.000  1.0
  Mg  Mg4  1  0.286  0.714  0.000  1.0
  Mg  Mg5  1  0.714  0.714  0.000  1.0
  Mg  Mg6  1  0.286  0.286  0.000  1.0
  Nb  Nb7  1  0.500  0.500  0.500  1.0
[/CIF]
.