The structure described by Na4Bi2O5 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form NaO4 trigonal pyramids that share corners with two equivalent Na(4)O4 trigonal pyramids, edges with two equivalent Na(3)O5 square pyramids, and  an edgeedge with one Na(4)O4 trigonal pyramid. In the second Na site, Na(2) is bonded in a distorted see-saw-like geometry to one O(2), one O(5), and two equivalent O(1) atoms. In the third Na site, Na(3) is bonded to one O(2), one O(4), one O(5), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share corners with two equivalent Na(4)O4 trigonal pyramids,  an edgeedge with one Na(3)O5 square pyramid, and edges with two equivalent Na(1)O4 trigonal pyramids. In the fourth Na site, Na(4) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form distorted NaO4 trigonal pyramids that share corners with two equivalent Na(3)O5 square pyramids, corners with two equivalent Na(1)O4 trigonal pyramids,  an edgeedge with one Na(1)O4 trigonal pyramid, and  an edgeedge with one Na(4)O4 trigonal pyramid. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 3-coordinate geometry to one O(1), one O(2), and one O(5) atom. In the second Bi site, Bi(2) is bonded in a distorted trigonal non-coplanar geometry to one O(3), one O(4), and one O(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), two equivalent Na(2), two equivalent Na(3), and one Bi(1) atom to form distorted ONa5Bi octahedra that share  a cornercorner with one O(4)Na3Bi trigonal pyramid, edges with two equivalent O(1)Na5Bi octahedra, edges with three equivalent O(2)Na4Bi square pyramids, and  an edgeedge with one O(4)Na3Bi trigonal pyramid. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), and one Bi(1) atom to form ONa4Bi square pyramids that share corners with three equivalent O(4)Na3Bi trigonal pyramids and edges with three equivalent O(1)Na5Bi octahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(4), and one Bi(2) atom. In the fourth O site, O(4) is bonded to one Na(1), one Na(3), one Na(4), and one Bi(2) atom to form distorted ONa3Bi trigonal pyramids that share  a cornercorner with one O(1)Na5Bi octahedra, corners with three equivalent O(2)Na4Bi square pyramids, and  an edgeedge with one O(1)Na5Bi octahedra. The corner-sharing octahedral tilt angles are 67°. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), one Na(3), one Bi(1), and one Bi(2) atom. is represented by the CIF card [CIF]
data_Na4Bi2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.186
_cell_length_b   8.744
_cell_length_c   16.205
_cell_angle_alpha   62.677
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   778.673
_cell_formula_units_Z   4
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  0.966  0.229  0.968  1.0
  Na  Na1  1  0.541  0.691  0.950  1.0
  Na  Na2  1  0.118  0.606  0.900  1.0
  Na  Na3  1  0.341  0.073  0.921  1.0
  Na  Na4  1  0.618  0.394  0.600  1.0
  Na  Na5  1  0.841  0.927  0.579  1.0
  Na  Na6  1  0.466  0.771  0.532  1.0
  Na  Na7  1  0.959  0.691  0.450  1.0
  Na  Na8  1  0.041  0.309  0.550  1.0
  Na  Na9  1  0.534  0.229  0.468  1.0
  Na  Na10  1  0.159  0.073  0.421  1.0
  Na  Na11  1  0.382  0.606  0.400  1.0
  Na  Na12  1  0.659  0.927  0.079  1.0
  Na  Na13  1  0.882  0.394  0.100  1.0
  Na  Na14  1  0.459  0.309  0.050  1.0
  Na  Na15  1  0.034  0.771  0.032  1.0
  Bi  Bi16  1  0.578  0.464  0.832  1.0
  Bi  Bi17  1  0.078  0.536  0.668  1.0
  Bi  Bi18  1  0.837  0.039  0.807  1.0
  Bi  Bi19  1  0.337  0.961  0.693  1.0
  Bi  Bi20  1  0.663  0.039  0.307  1.0
  Bi  Bi21  1  0.163  0.961  0.193  1.0
  Bi  Bi22  1  0.922  0.464  0.332  1.0
  Bi  Bi23  1  0.422  0.536  0.168  1.0
  O  O24  1  0.755  0.469  0.941  1.0
  O  O25  1  0.300  0.350  0.909  1.0
  O  O26  1  0.718  0.106  0.908  1.0
  O  O27  1  0.120  0.910  0.875  1.0
  O  O28  1  0.461  0.722  0.799  1.0
  O  O29  1  0.800  0.650  0.591  1.0
  O  O30  1  0.961  0.278  0.701  1.0
  O  O31  1  0.620  0.090  0.625  1.0
  O  O32  1  0.255  0.531  0.559  1.0
  O  O33  1  0.218  0.894  0.592  1.0
  O  O34  1  0.782  0.106  0.408  1.0
  O  O35  1  0.745  0.469  0.441  1.0
  O  O36  1  0.380  0.910  0.375  1.0
  O  O37  1  0.039  0.722  0.299  1.0
  O  O38  1  0.200  0.350  0.409  1.0
  O  O39  1  0.539  0.278  0.201  1.0
  O  O40  1  0.880  0.090  0.125  1.0
  O  O41  1  0.282  0.894  0.092  1.0
  O  O42  1  0.700  0.650  0.091  1.0
  O  O43  1  0.245  0.531  0.059  1.0
[/CIF]
.
The structure described by Na4Bi2O5 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form NaO4 trigonal pyramids that share corners with two equivalent Na(4)O4 trigonal pyramids, edges with two equivalent Na(3)O5 square pyramids, and  an edgeedge with one Na(4)O4 trigonal pyramid. In the second Na site, Na(2) is bonded in a distorted see-saw-like geometry to one O(2), one O(5), and two equivalent O(1) atoms. In the third Na site, Na(3) is bonded to one O(2), one O(4), one O(5), and two equivalent O(1) atoms to form distorted NaO5 square pyramids that share corners with two equivalent Na(4)O4 trigonal pyramids,  an edgeedge with one Na(3)O5 square pyramid, and edges with two equivalent Na(1)O4 trigonal pyramids. In the fourth Na site, Na(4) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form distorted NaO4 trigonal pyramids that share corners with two equivalent Na(3)O5 square pyramids, corners with two equivalent Na(1)O4 trigonal pyramids,  an edgeedge with one Na(1)O4 trigonal pyramid, and  an edgeedge with one Na(4)O4 trigonal pyramid. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 3-coordinate geometry to one O(1), one O(2), and one O(5) atom. In the second Bi site, Bi(2) is bonded in a distorted trigonal non-coplanar geometry to one O(3), one O(4), and one O(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), two equivalent Na(2), two equivalent Na(3), and one Bi(1) atom to form distorted ONa5Bi octahedra that share  a cornercorner with one O(4)Na3Bi trigonal pyramid, edges with two equivalent O(1)Na5Bi octahedra, edges with three equivalent O(2)Na4Bi square pyramids, and  an edgeedge with one O(4)Na3Bi trigonal pyramid. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), and one Bi(1) atom to form ONa4Bi square pyramids that share corners with three equivalent O(4)Na3Bi trigonal pyramids and edges with three equivalent O(1)Na5Bi octahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(4), and one Bi(2) atom. In the fourth O site, O(4) is bonded to one Na(1), one Na(3), one Na(4), and one Bi(2) atom to form distorted ONa3Bi trigonal pyramids that share  a cornercorner with one O(1)Na5Bi octahedra, corners with three equivalent O(2)Na4Bi square pyramids, and  an edgeedge with one O(1)Na5Bi octahedra. The corner-sharing octahedral tilt angles are 67°. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), one Na(3), one Bi(1), and one Bi(2) atom. is represented by the CIF card [CIF]
data_Na4Bi2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.186
_cell_length_b   8.744
_cell_length_c   16.205
_cell_angle_alpha   62.677
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   778.673
_cell_formula_units_Z   4
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  0.966  0.229  0.968  1.0
  Na  Na1  1  0.541  0.691  0.950  1.0
  Na  Na2  1  0.118  0.606  0.900  1.0
  Na  Na3  1  0.341  0.073  0.921  1.0
  Na  Na4  1  0.618  0.394  0.600  1.0
  Na  Na5  1  0.841  0.927  0.579  1.0
  Na  Na6  1  0.466  0.771  0.532  1.0
  Na  Na7  1  0.959  0.691  0.450  1.0
  Na  Na8  1  0.041  0.309  0.550  1.0
  Na  Na9  1  0.534  0.229  0.468  1.0
  Na  Na10  1  0.159  0.073  0.421  1.0
  Na  Na11  1  0.382  0.606  0.400  1.0
  Na  Na12  1  0.659  0.927  0.079  1.0
  Na  Na13  1  0.882  0.394  0.100  1.0
  Na  Na14  1  0.459  0.309  0.050  1.0
  Na  Na15  1  0.034  0.771  0.032  1.0
  Bi  Bi16  1  0.578  0.464  0.832  1.0
  Bi  Bi17  1  0.078  0.536  0.668  1.0
  Bi  Bi18  1  0.837  0.039  0.807  1.0
  Bi  Bi19  1  0.337  0.961  0.693  1.0
  Bi  Bi20  1  0.663  0.039  0.307  1.0
  Bi  Bi21  1  0.163  0.961  0.193  1.0
  Bi  Bi22  1  0.922  0.464  0.332  1.0
  Bi  Bi23  1  0.422  0.536  0.168  1.0
  O  O24  1  0.755  0.469  0.941  1.0
  O  O25  1  0.300  0.350  0.909  1.0
  O  O26  1  0.718  0.106  0.908  1.0
  O  O27  1  0.120  0.910  0.875  1.0
  O  O28  1  0.461  0.722  0.799  1.0
  O  O29  1  0.800  0.650  0.591  1.0
  O  O30  1  0.961  0.278  0.701  1.0
  O  O31  1  0.620  0.090  0.625  1.0
  O  O32  1  0.255  0.531  0.559  1.0
  O  O33  1  0.218  0.894  0.592  1.0
  O  O34  1  0.782  0.106  0.408  1.0
  O  O35  1  0.745  0.469  0.441  1.0
  O  O36  1  0.380  0.910  0.375  1.0
  O  O37  1  0.039  0.722  0.299  1.0
  O  O38  1  0.200  0.350  0.409  1.0
  O  O39  1  0.539  0.278  0.201  1.0
  O  O40  1  0.880  0.090  0.125  1.0
  O  O41  1  0.282  0.894  0.092  1.0
  O  O42  1  0.700  0.650  0.091  1.0
  O  O43  1  0.245  0.531  0.059  1.0
[/CIF]
.