The compound described by Na4Bi2O5 crystallizes in the triclinic P-1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra, edges with three equivalent Na(3)O6 octahedra, and edges with four equivalent Na(2)O5 square pyramids. The corner-sharing octahedral tilt angles are 7°. In the second Na site, Na(2) is bonded to one O(5), two equivalent O(3), and two equivalent O(4) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Na(3)O6 octahedra, corners with two equivalent Na(2)O5 square pyramids,  an edgeedge with one Na(3)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and  an edgeedge with one Na(2)O5 square pyramid. The corner-sharing octahedral tilt angles are 16°. In the third Na site, Na(3) is bonded to one O(1), one O(4), one O(5), and three equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra,  a cornercorner with one Na(2)O5 square pyramid, edges with two equivalent Na(3)O6 octahedra, edges with three equivalent Na(1)O6 octahedra, and  an edgeedge with one Na(2)O5 square pyramid. The corner-sharing octahedral tilt angles are 7°. In the fourth Na site, Na(4) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(5), and two equivalent O(1) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(3), and two equivalent O(5) atoms. In the second Bi site, Bi(2) is bonded in a 3-coordinate geometry to one O(1), one O(2), and one O(4) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(3), two equivalent Na(4), and one Bi(2) atom to form distorted ONa4Bi trigonal bipyramids that share  a cornercorner with one O(2)Na4Bi2 octahedra, corners with two equivalent O(3)Na5Bi octahedra, corners with two equivalent O(4)Na5Bi octahedra,  a cornercorner with one O(5)Na3Bi2 square pyramid,  an edgeedge with one O(3)Na5Bi octahedra,  an edgeedge with one O(4)Na5Bi octahedra, edges with two equivalent O(2)Na4Bi2 octahedra,  an edgeedge with one O(5)Na3Bi2 square pyramid, and  an edgeedge with one O(1)Na4Bi trigonal bipyramid. The corner-sharing octahedral tilt angles range from 10-85°. In the second O site, O(2) is bonded to one Na(1), three equivalent Na(3), one Bi(1), and one Bi(2) atom to form ONa4Bi2 octahedra that share  a cornercorner with one O(3)Na5Bi octahedra, corners with two equivalent O(2)Na4Bi2 octahedra, corners with three equivalent O(5)Na3Bi2 square pyramids,  a cornercorner with one O(1)Na4Bi trigonal bipyramid,  an edgeedge with one O(3)Na5Bi octahedra, edges with two equivalent O(2)Na4Bi2 octahedra, edges with three equivalent O(4)Na5Bi octahedra,  an edgeedge with one O(5)Na3Bi2 square pyramid, and edges with two equivalent O(1)Na4Bi trigonal bipyramids. The corner-sharing octahedral tilt angles range from 5-7°. In the third O site, O(3) is bonded to one Na(4), two equivalent Na(1), two equivalent Na(2), and one Bi(1) atom to form ONa5Bi octahedra that share  a cornercorner with one O(2)Na4Bi2 octahedra, corners with two equivalent O(3)Na5Bi octahedra,  a cornercorner with one O(5)Na3Bi2 square pyramid, corners with two equivalent O(1)Na4Bi trigonal bipyramids,  an edgeedge with one O(2)Na4Bi2 octahedra,  an edgeedge with one O(3)Na5Bi octahedra, edges with four equivalent O(4)Na5Bi octahedra, edges with two equivalent O(5)Na3Bi2 square pyramids, and  an edgeedge with one O(1)Na4Bi trigonal bipyramid. The corner-sharing octahedral tilt angles range from 5-19°. In the fourth O site, O(4) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Bi(2) atom to form ONa5Bi octahedra that share corners with two equivalent O(4)Na5Bi octahedra,  a cornercorner with one O(5)Na3Bi2 square pyramid, corners with two equivalent O(1)Na4Bi trigonal bipyramids,  an edgeedge with one O(4)Na5Bi octahedra, edges with three equivalent O(2)Na4Bi2 octahedra, edges with four equivalent O(3)Na5Bi octahedra,  an edgeedge with one O(5)Na3Bi2 square pyramid, and  an edgeedge with one O(1)Na4Bi trigonal bipyramid. The corner-sharing octahedral tilt angles are 7°. In the fifth O site, O(5) is bonded to one Na(2), one Na(3), one Na(4), and two equivalent Bi(1) atoms to form distorted ONa3Bi2 square pyramids that share  a cornercorner with one O(3)Na5Bi octahedra,  a cornercorner with one O(4)Na5Bi octahedra, corners with three equivalent O(2)Na4Bi2 octahedra,  a cornercorner with one O(1)Na4Bi trigonal bipyramid,  an edgeedge with one O(2)Na4Bi2 octahedra,  an edgeedge with one O(4)Na5Bi octahedra, edges with two equivalent O(3)Na5Bi octahedra,  an edgeedge with one O(5)Na3Bi2 square pyramid, and  an edgeedge with one O(1)Na4Bi trigonal bipyramid. The corner-sharing octahedral tilt angles range from 9-88°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na4Bi2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.025
_cell_length_b   8.752
_cell_length_c   8.908
_cell_angle_alpha   66.937
_cell_angle_beta   74.046
_cell_angle_gamma   73.095
_symmetry_Int_Tables_number   1
_cell_volume   339.043
_cell_formula_units_Z   2
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
  Na  Na0  1  0.081  0.796  0.548  1.0
  Na  Na1  1  0.589  0.005  0.325  1.0
  Na  Na2  1  0.248  0.380  0.626  1.0
  Na  Na3  1  0.907  0.702  0.962  1.0
  Na  Na4  1  0.093  0.298  0.038  1.0
  Na  Na5  1  0.752  0.620  0.374  1.0
  Na  Na6  1  0.411  0.995  0.675  1.0
  Na  Na7  1  0.919  0.204  0.452  1.0
  Bi  Bi8  1  0.760  0.125  0.870  1.0
  Bi  Bi9  1  0.420  0.438  0.233  1.0
  Bi  Bi10  1  0.580  0.562  0.767  1.0
  Bi  Bi11  1  0.240  0.875  0.130  1.0
  O  O12  1  0.161  0.545  0.794  1.0
  O  O13  1  0.247  0.620  0.356  1.0
  O  O14  1  0.883  0.974  0.726  1.0
  O  O15  1  0.417  0.224  0.441  1.0
  O  O16  1  0.181  0.123  0.880  1.0
  O  O17  1  0.819  0.877  0.120  1.0
  O  O18  1  0.583  0.776  0.559  1.0
  O  O19  1  0.117  0.026  0.274  1.0
  O  O20  1  0.753  0.380  0.644  1.0
  O  O21  1  0.839  0.455  0.206  1.0
[/CIF]
.
The compound described by Na4Bi2O5 crystallizes in the triclinic P-1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra, edges with three equivalent Na(3)O6 octahedra, and edges with four equivalent Na(2)O5 square pyramids. The corner-sharing octahedral tilt angles are 7°. In the second Na site, Na(2) is bonded to one O(5), two equivalent O(3), and two equivalent O(4) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Na(3)O6 octahedra, corners with two equivalent Na(2)O5 square pyramids,  an edgeedge with one Na(3)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and  an edgeedge with one Na(2)O5 square pyramid. The corner-sharing octahedral tilt angles are 16°. In the third Na site, Na(3) is bonded to one O(1), one O(4), one O(5), and three equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Na(3)O6 octahedra,  a cornercorner with one Na(2)O5 square pyramid, edges with two equivalent Na(3)O6 octahedra, edges with three equivalent Na(1)O6 octahedra, and  an edgeedge with one Na(2)O5 square pyramid. The corner-sharing octahedral tilt angles are 7°. In the fourth Na site, Na(4) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(5), and two equivalent O(1) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(3), and two equivalent O(5) atoms. In the second Bi site, Bi(2) is bonded in a 3-coordinate geometry to one O(1), one O(2), and one O(4) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(3), two equivalent Na(4), and one Bi(2) atom to form distorted ONa4Bi trigonal bipyramids that share  a cornercorner with one O(2)Na4Bi2 octahedra, corners with two equivalent O(3)Na5Bi octahedra, corners with two equivalent O(4)Na5Bi octahedra,  a cornercorner with one O(5)Na3Bi2 square pyramid,  an edgeedge with one O(3)Na5Bi octahedra,  an edgeedge with one O(4)Na5Bi octahedra, edges with two equivalent O(2)Na4Bi2 octahedra,  an edgeedge with one O(5)Na3Bi2 square pyramid, and  an edgeedge with one O(1)Na4Bi trigonal bipyramid. The corner-sharing octahedral tilt angles range from 10-85°. In the second O site, O(2) is bonded to one Na(1), three equivalent Na(3), one Bi(1), and one Bi(2) atom to form ONa4Bi2 octahedra that share  a cornercorner with one O(3)Na5Bi octahedra, corners with two equivalent O(2)Na4Bi2 octahedra, corners with three equivalent O(5)Na3Bi2 square pyramids,  a cornercorner with one O(1)Na4Bi trigonal bipyramid,  an edgeedge with one O(3)Na5Bi octahedra, edges with two equivalent O(2)Na4Bi2 octahedra, edges with three equivalent O(4)Na5Bi octahedra,  an edgeedge with one O(5)Na3Bi2 square pyramid, and edges with two equivalent O(1)Na4Bi trigonal bipyramids. The corner-sharing octahedral tilt angles range from 5-7°. In the third O site, O(3) is bonded to one Na(4), two equivalent Na(1), two equivalent Na(2), and one Bi(1) atom to form ONa5Bi octahedra that share  a cornercorner with one O(2)Na4Bi2 octahedra, corners with two equivalent O(3)Na5Bi octahedra,  a cornercorner with one O(5)Na3Bi2 square pyramid, corners with two equivalent O(1)Na4Bi trigonal bipyramids,  an edgeedge with one O(2)Na4Bi2 octahedra,  an edgeedge with one O(3)Na5Bi octahedra, edges with four equivalent O(4)Na5Bi octahedra, edges with two equivalent O(5)Na3Bi2 square pyramids, and  an edgeedge with one O(1)Na4Bi trigonal bipyramid. The corner-sharing octahedral tilt angles range from 5-19°. In the fourth O site, O(4) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Bi(2) atom to form ONa5Bi octahedra that share corners with two equivalent O(4)Na5Bi octahedra,  a cornercorner with one O(5)Na3Bi2 square pyramid, corners with two equivalent O(1)Na4Bi trigonal bipyramids,  an edgeedge with one O(4)Na5Bi octahedra, edges with three equivalent O(2)Na4Bi2 octahedra, edges with four equivalent O(3)Na5Bi octahedra,  an edgeedge with one O(5)Na3Bi2 square pyramid, and  an edgeedge with one O(1)Na4Bi trigonal bipyramid. The corner-sharing octahedral tilt angles are 7°. In the fifth O site, O(5) is bonded to one Na(2), one Na(3), one Na(4), and two equivalent Bi(1) atoms to form distorted ONa3Bi2 square pyramids that share  a cornercorner with one O(3)Na5Bi octahedra,  a cornercorner with one O(4)Na5Bi octahedra, corners with three equivalent O(2)Na4Bi2 octahedra,  a cornercorner with one O(1)Na4Bi trigonal bipyramid,  an edgeedge with one O(2)Na4Bi2 octahedra,  an edgeedge with one O(4)Na5Bi octahedra, edges with two equivalent O(3)Na5Bi octahedra,  an edgeedge with one O(5)Na3Bi2 square pyramid, and  an edgeedge with one O(1)Na4Bi trigonal bipyramid. The corner-sharing octahedral tilt angles range from 9-88°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na4Bi2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.025
_cell_length_b   8.752
_cell_length_c   8.908
_cell_angle_alpha   66.937
_cell_angle_beta   74.046
_cell_angle_gamma   73.095
_symmetry_Int_Tables_number   1
_cell_volume   339.043
_cell_formula_units_Z   2
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
  Na  Na0  1  0.081  0.796  0.548  1.0
  Na  Na1  1  0.589  0.005  0.325  1.0
  Na  Na2  1  0.248  0.380  0.626  1.0
  Na  Na3  1  0.907  0.702  0.962  1.0
  Na  Na4  1  0.093  0.298  0.038  1.0
  Na  Na5  1  0.752  0.620  0.374  1.0
  Na  Na6  1  0.411  0.995  0.675  1.0
  Na  Na7  1  0.919  0.204  0.452  1.0
  Bi  Bi8  1  0.760  0.125  0.870  1.0
  Bi  Bi9  1  0.420  0.438  0.233  1.0
  Bi  Bi10  1  0.580  0.562  0.767  1.0
  Bi  Bi11  1  0.240  0.875  0.130  1.0
  O  O12  1  0.161  0.545  0.794  1.0
  O  O13  1  0.247  0.620  0.356  1.0
  O  O14  1  0.883  0.974  0.726  1.0
  O  O15  1  0.417  0.224  0.441  1.0
  O  O16  1  0.181  0.123  0.880  1.0
  O  O17  1  0.819  0.877  0.120  1.0
  O  O18  1  0.583  0.776  0.559  1.0
  O  O19  1  0.117  0.026  0.274  1.0
  O  O20  1  0.753  0.380  0.644  1.0
  O  O21  1  0.839  0.455  0.206  1.0
[/CIF]
.