The crystal structure described by Na5TaO5 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted NaO4 trigonal pyramids that share corners with four equivalent Na(2)O5 square pyramids, corners with two equivalent Na(3)O5 trigonal bipyramids, corners with two equivalent Ta(1)O5 trigonal bipyramids,  a cornercorner with one Na(1)O4 trigonal pyramid, edges with two equivalent Na(2)O5 square pyramids,  an edgeedge with one Na(3)O5 trigonal bipyramid,  an edgeedge with one Ta(1)O5 trigonal bipyramid, and  an edgeedge with one Na(1)O4 trigonal pyramid. In the second Na site, Na(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Na(2)O5 square pyramid,  a cornercorner with one Na(3)O5 trigonal bipyramid, corners with three equivalent Ta(1)O5 trigonal bipyramids, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Na(2)O5 square pyramids,  an edgeedge with one Ta(1)O5 trigonal bipyramid, edges with two equivalent Na(3)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. In the third Na site, Na(3) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Na(2)O5 square pyramids,  a cornercorner with one Ta(1)O5 trigonal bipyramid, corners with four equivalent Na(1)O4 trigonal pyramids, edges with four equivalent Na(2)O5 square pyramids, edges with two equivalent Ta(1)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. Ta(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form TaO5 trigonal bipyramids that share corners with six equivalent Na(2)O5 square pyramids,  a cornercorner with one Na(3)O5 trigonal bipyramid, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Na(2)O5 square pyramids, edges with two equivalent Na(3)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Ta(1) atom to form distorted ONa5Ta octahedra that share corners with four equivalent O(3)Na5Ta octahedra, corners with two equivalent O(2)Na4Ta square pyramids, edges with four equivalent O(3)Na5Ta octahedra, and edges with four equivalent O(2)Na4Ta square pyramids. The corner-sharing octahedral tilt angles range from 16-30°. In the second O site, O(2) is bonded to one Na(1), one Na(3), two equivalent Na(2), and one Ta(1) atom to form distorted ONa4Ta square pyramids that share  a cornercorner with one O(1)Na5Ta octahedra, corners with two equivalent O(3)Na5Ta octahedra, corners with two equivalent O(2)Na4Ta square pyramids, edges with two equivalent O(1)Na5Ta octahedra, edges with four equivalent O(3)Na5Ta octahedra, and  an edgeedge with one O(2)Na4Ta square pyramid. The corner-sharing octahedral tilt angles range from 31-68°. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Ta(1) atom to form distorted ONa5Ta octahedra that share corners with two equivalent O(1)Na5Ta octahedra, corners with two equivalent O(3)Na5Ta octahedra, corners with two equivalent O(2)Na4Ta square pyramids, edges with two equivalent O(1)Na5Ta octahedra, edges with two equivalent O(3)Na5Ta octahedra, and edges with four equivalent O(2)Na4Ta square pyramids. The corner-sharing octahedral tilt angles range from 9-33°. is represented by the CIF file [CIF]
data_Na5TaO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.970
_cell_length_b   5.970
_cell_length_c   9.976
_cell_angle_alpha   81.330
_cell_angle_beta   81.330
_cell_angle_gamma   116.780
_symmetry_Int_Tables_number   1
_cell_volume   304.014
_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  0.324  0.006  0.922  1.0
  Na  Na1  1  0.994  0.676  0.578  1.0
  Na  Na2  1  0.444  0.214  0.549  1.0
  Na  Na3  1  0.786  0.556  0.951  1.0
  Na  Na4  1  0.556  0.786  0.451  1.0
  Na  Na5  1  0.214  0.444  0.049  1.0
  Na  Na6  1  0.670  0.330  0.250  1.0
  Na  Na7  1  0.330  0.670  0.750  1.0
  Na  Na8  1  0.006  0.324  0.422  1.0
  Na  Na9  1  0.676  0.994  0.078  1.0
  Ta  Ta10  1  0.092  0.908  0.250  1.0
  Ta  Ta11  1  0.908  0.092  0.750  1.0
  O  O12  1  0.905  0.095  0.250  1.0
  O  O13  1  0.095  0.905  0.750  1.0
  O  O14  1  0.304  0.962  0.382  1.0
  O  O15  1  0.038  0.696  0.118  1.0
  O  O16  1  0.404  0.190  0.104  1.0
  O  O17  1  0.810  0.596  0.396  1.0
  O  O18  1  0.596  0.810  0.896  1.0
  O  O19  1  0.190  0.404  0.604  1.0
  O  O20  1  0.696  0.038  0.618  1.0
  O  O21  1  0.962  0.304  0.882  1.0
[/CIF]
.
The crystal structure described by Na5TaO5 crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted NaO4 trigonal pyramids that share corners with four equivalent Na(2)O5 square pyramids, corners with two equivalent Na(3)O5 trigonal bipyramids, corners with two equivalent Ta(1)O5 trigonal bipyramids,  a cornercorner with one Na(1)O4 trigonal pyramid, edges with two equivalent Na(2)O5 square pyramids,  an edgeedge with one Na(3)O5 trigonal bipyramid,  an edgeedge with one Ta(1)O5 trigonal bipyramid, and  an edgeedge with one Na(1)O4 trigonal pyramid. In the second Na site, Na(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Na(2)O5 square pyramid,  a cornercorner with one Na(3)O5 trigonal bipyramid, corners with three equivalent Ta(1)O5 trigonal bipyramids, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Na(2)O5 square pyramids,  an edgeedge with one Ta(1)O5 trigonal bipyramid, edges with two equivalent Na(3)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. In the third Na site, Na(3) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Na(2)O5 square pyramids,  a cornercorner with one Ta(1)O5 trigonal bipyramid, corners with four equivalent Na(1)O4 trigonal pyramids, edges with four equivalent Na(2)O5 square pyramids, edges with two equivalent Ta(1)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. Ta(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form TaO5 trigonal bipyramids that share corners with six equivalent Na(2)O5 square pyramids,  a cornercorner with one Na(3)O5 trigonal bipyramid, corners with four equivalent Na(1)O4 trigonal pyramids, edges with two equivalent Na(2)O5 square pyramids, edges with two equivalent Na(3)O5 trigonal bipyramids, and edges with two equivalent Na(1)O4 trigonal pyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Ta(1) atom to form distorted ONa5Ta octahedra that share corners with four equivalent O(3)Na5Ta octahedra, corners with two equivalent O(2)Na4Ta square pyramids, edges with four equivalent O(3)Na5Ta octahedra, and edges with four equivalent O(2)Na4Ta square pyramids. The corner-sharing octahedral tilt angles range from 16-30°. In the second O site, O(2) is bonded to one Na(1), one Na(3), two equivalent Na(2), and one Ta(1) atom to form distorted ONa4Ta square pyramids that share  a cornercorner with one O(1)Na5Ta octahedra, corners with two equivalent O(3)Na5Ta octahedra, corners with two equivalent O(2)Na4Ta square pyramids, edges with two equivalent O(1)Na5Ta octahedra, edges with four equivalent O(3)Na5Ta octahedra, and  an edgeedge with one O(2)Na4Ta square pyramid. The corner-sharing octahedral tilt angles range from 31-68°. In the third O site, O(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Ta(1) atom to form distorted ONa5Ta octahedra that share corners with two equivalent O(1)Na5Ta octahedra, corners with two equivalent O(3)Na5Ta octahedra, corners with two equivalent O(2)Na4Ta square pyramids, edges with two equivalent O(1)Na5Ta octahedra, edges with two equivalent O(3)Na5Ta octahedra, and edges with four equivalent O(2)Na4Ta square pyramids. The corner-sharing octahedral tilt angles range from 9-33°. is represented by the CIF file [CIF]
data_Na5TaO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.970
_cell_length_b   5.970
_cell_length_c   9.976
_cell_angle_alpha   81.330
_cell_angle_beta   81.330
_cell_angle_gamma   116.780
_symmetry_Int_Tables_number   1
_cell_volume   304.014
_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  0.324  0.006  0.922  1.0
  Na  Na1  1  0.994  0.676  0.578  1.0
  Na  Na2  1  0.444  0.214  0.549  1.0
  Na  Na3  1  0.786  0.556  0.951  1.0
  Na  Na4  1  0.556  0.786  0.451  1.0
  Na  Na5  1  0.214  0.444  0.049  1.0
  Na  Na6  1  0.670  0.330  0.250  1.0
  Na  Na7  1  0.330  0.670  0.750  1.0
  Na  Na8  1  0.006  0.324  0.422  1.0
  Na  Na9  1  0.676  0.994  0.078  1.0
  Ta  Ta10  1  0.092  0.908  0.250  1.0
  Ta  Ta11  1  0.908  0.092  0.750  1.0
  O  O12  1  0.905  0.095  0.250  1.0
  O  O13  1  0.095  0.905  0.750  1.0
  O  O14  1  0.304  0.962  0.382  1.0
  O  O15  1  0.038  0.696  0.118  1.0
  O  O16  1  0.404  0.190  0.104  1.0
  O  O17  1  0.810  0.596  0.396  1.0
  O  O18  1  0.596  0.810  0.896  1.0
  O  O19  1  0.190  0.404  0.604  1.0
  O  O20  1  0.696  0.038  0.618  1.0
  O  O21  1  0.962  0.304  0.882  1.0
[/CIF]
.