The structure described by Rb3NbO8 crystallizes in the tetragonal I-42m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to four equivalent O(1) and four equivalent O(2) atoms to form RbO8 hexagonal bipyramids that share corners with four equivalent Nb(1)O8 hexagonal bipyramids, corners with four equivalent O(1)Rb3NbO trigonal bipyramids, and edges with two equivalent Nb(1)O8 hexagonal bipyramids. In the second Rb site, Rb(2) is bonded in a 12-coordinate geometry to four equivalent O(1) and eight equivalent O(2) atoms. Nb(1) is bonded to four equivalent O(1) and four equivalent O(2) atoms to form distorted NbO8 hexagonal bipyramids that share corners with four equivalent Rb(1)O8 hexagonal bipyramids, corners with four equivalent O(1)Rb3NbO trigonal bipyramids, and edges with two equivalent Rb(1)O8 hexagonal bipyramids. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Rb(1), two equivalent Rb(2), one Nb(1), and one O(2) atom to form distorted ORb3NbO trigonal bipyramids that share  a cornercorner with one Rb(1)O8 hexagonal bipyramid,  a cornercorner with one Nb(1)O8 hexagonal bipyramid, corners with ten equivalent O(1)Rb3NbO trigonal bipyramids, and  an edgeedge with one O(1)Rb3NbO trigonal bipyramid. In the second O site, O(2) is bonded in a 7-coordinate geometry to one Rb(1), four equivalent Rb(2), one Nb(1), and one O(1) atom. is represented by the CIF file [CIF]
data_Rb3NbO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.418
_cell_length_b   6.418
_cell_length_c   6.418
_cell_angle_alpha   103.286
_cell_angle_beta   112.650
_cell_angle_gamma   112.650
_symmetry_Int_Tables_number   1
_cell_volume   201.792
_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  0.500  0.500  1.0
  Rb  Rb1  1  0.500  0.750  0.250  1.0
  Rb  Rb2  1  0.500  0.250  0.750  1.0
  Nb  Nb3  1  0.000  0.000  0.000  1.0
  O  O4  1  0.274  0.951  0.951  1.0
  O  O5  1  0.000  0.049  0.324  1.0
  O  O6  1  0.000  0.324  0.049  1.0
  O  O7  1  0.726  0.676  0.676  1.0
  O  O8  1  0.587  0.773  0.773  1.0
  O  O9  1  0.000  0.227  0.814  1.0
  O  O10  1  0.000  0.814  0.227  1.0
  O  O11  1  0.413  0.186  0.186  1.0
[/CIF]
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The structure described by Rb3NbO8 crystallizes in the tetragonal I-42m space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded to four equivalent O(1) and four equivalent O(2) atoms to form RbO8 hexagonal bipyramids that share corners with four equivalent Nb(1)O8 hexagonal bipyramids, corners with four equivalent O(1)Rb3NbO trigonal bipyramids, and edges with two equivalent Nb(1)O8 hexagonal bipyramids. In the second Rb site, Rb(2) is bonded in a 12-coordinate geometry to four equivalent O(1) and eight equivalent O(2) atoms. Nb(1) is bonded to four equivalent O(1) and four equivalent O(2) atoms to form distorted NbO8 hexagonal bipyramids that share corners with four equivalent Rb(1)O8 hexagonal bipyramids, corners with four equivalent O(1)Rb3NbO trigonal bipyramids, and edges with two equivalent Rb(1)O8 hexagonal bipyramids. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Rb(1), two equivalent Rb(2), one Nb(1), and one O(2) atom to form distorted ORb3NbO trigonal bipyramids that share  a cornercorner with one Rb(1)O8 hexagonal bipyramid,  a cornercorner with one Nb(1)O8 hexagonal bipyramid, corners with ten equivalent O(1)Rb3NbO trigonal bipyramids, and  an edgeedge with one O(1)Rb3NbO trigonal bipyramid. In the second O site, O(2) is bonded in a 7-coordinate geometry to one Rb(1), four equivalent Rb(2), one Nb(1), and one O(1) atom. is represented by the CIF file [CIF]
data_Rb3NbO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.418
_cell_length_b   6.418
_cell_length_c   6.418
_cell_angle_alpha   103.286
_cell_angle_beta   112.650
_cell_angle_gamma   112.650
_symmetry_Int_Tables_number   1
_cell_volume   201.792
_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  0.500  0.500  1.0
  Rb  Rb1  1  0.500  0.750  0.250  1.0
  Rb  Rb2  1  0.500  0.250  0.750  1.0
  Nb  Nb3  1  0.000  0.000  0.000  1.0
  O  O4  1  0.274  0.951  0.951  1.0
  O  O5  1  0.000  0.049  0.324  1.0
  O  O6  1  0.000  0.324  0.049  1.0
  O  O7  1  0.726  0.676  0.676  1.0
  O  O8  1  0.587  0.773  0.773  1.0
  O  O9  1  0.000  0.227  0.814  1.0
  O  O10  1  0.000  0.814  0.227  1.0
  O  O11  1  0.413  0.186  0.186  1.0
[/CIF]
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