The structure described by Na2TbO3 is Caswellsilverite-like structured and crystallizes in the triclinic P-1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form NaO6 octahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Tb(1)O6 octahedra,  a cornercorner with one Tb(2)O6 octahedra, corners with two equivalent Na(2)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Tb(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with four equivalent Na(3)O6 octahedra, and edges with four equivalent Tb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-13°. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Tb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Tb(2)O6 octahedra, edges with three equivalent Na(2)O6 octahedra, and edges with three equivalent Tb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-15°. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form NaO6 octahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Tb(1)O6 octahedra,  a cornercorner with one Tb(2)O6 octahedra, corners with two equivalent Na(2)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Tb(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Tb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-15°. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TbO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Tb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Tb(2)O6 octahedra, and edges with six equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-8°. In the second Tb site, Tb(2) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form TbO6 octahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Tb(1)O6 octahedra,  a cornercorner with one Tb(2)O6 octahedra, corners with two equivalent Na(2)O6 octahedra,  an edgeedge with one Tb(1)O6 octahedra,  an edgeedge with one Tb(2)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Na(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. 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(2), one Tb(1), and one Tb(2) atom to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-15°. In the second O site, O(2) is bonded to one Na(1), one Na(3), two equivalent Na(2), one Tb(1), and one Tb(2) atom to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the third O site, O(3) is bonded to one Na(1), one Na(3), two equivalent Na(2), one Tb(1), and one Tb(2) atom to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-15°. In the fourth O site, O(4) is bonded to two equivalent Na(1), two equivalent Na(3), and two equivalent Tb(2) atoms to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 4-12°. In the fifth O site, O(5) is bonded to two equivalent Na(1), two equivalent Na(3), and two equivalent Tb(2) atoms to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 2-6°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2TbO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.852
_cell_length_b   5.918
_cell_length_c   8.893
_cell_angle_alpha   70.912
_cell_angle_beta   72.388
_cell_angle_gamma   61.211
_symmetry_Int_Tables_number   1
_cell_volume   251.140
_cell_formula_units_Z   3
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  0.716  0.052  0.334  1.0
  Na  Na1  1  0.826  0.848  0.001  1.0
  Na  Na2  1  0.174  0.152  0.999  1.0
  Na  Na3  1  0.392  0.725  0.334  1.0
  Na  Na4  1  0.284  0.948  0.666  1.0
  Na  Na5  1  0.608  0.275  0.666  1.0
  Tb  Tb6  1  0.500  0.500  0.000  1.0
  Tb  Tb7  1  0.045  0.375  0.333  1.0
  Tb  Tb8  1  0.955  0.625  0.667  1.0
  O  O9  1  0.136  0.728  0.163  1.0
  O  O10  1  0.864  0.272  0.837  1.0
  O  O11  1  0.231  0.558  0.829  1.0
  O  O12  1  0.419  0.151  0.169  1.0
  O  O13  1  0.581  0.849  0.831  1.0
  O  O14  1  0.283  0.354  0.506  1.0
  O  O15  1  0.769  0.442  0.171  1.0
  O  O16  1  0.717  0.646  0.494  1.0
  O  O17  1  0.000  0.000  0.500  1.0
[/CIF]
.
The structure described by Na2TbO3 is Caswellsilverite-like structured and crystallizes in the triclinic P-1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form NaO6 octahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Tb(1)O6 octahedra,  a cornercorner with one Tb(2)O6 octahedra, corners with two equivalent Na(2)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Tb(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with four equivalent Na(3)O6 octahedra, and edges with four equivalent Tb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-13°. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form NaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Tb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Tb(2)O6 octahedra, edges with three equivalent Na(2)O6 octahedra, and edges with three equivalent Tb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-15°. In the third Na site, Na(3) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form NaO6 octahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Tb(1)O6 octahedra,  a cornercorner with one Tb(2)O6 octahedra, corners with two equivalent Na(2)O6 octahedra,  an edgeedge with one Na(3)O6 octahedra,  an edgeedge with one Tb(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Tb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-15°. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TbO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(3)O6 octahedra, corners with two equivalent Tb(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(3)O6 octahedra, edges with two equivalent Tb(2)O6 octahedra, and edges with six equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-8°. In the second Tb site, Tb(2) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form TbO6 octahedra that share  a cornercorner with one Na(1)O6 octahedra,  a cornercorner with one Na(3)O6 octahedra,  a cornercorner with one Tb(1)O6 octahedra,  a cornercorner with one Tb(2)O6 octahedra, corners with two equivalent Na(2)O6 octahedra,  an edgeedge with one Tb(1)O6 octahedra,  an edgeedge with one Tb(2)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Na(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-10°. 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(2), one Tb(1), and one Tb(2) atom to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-15°. In the second O site, O(2) is bonded to one Na(1), one Na(3), two equivalent Na(2), one Tb(1), and one Tb(2) atom to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the third O site, O(3) is bonded to one Na(1), one Na(3), two equivalent Na(2), one Tb(1), and one Tb(2) atom to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 0-15°. In the fourth O site, O(4) is bonded to two equivalent Na(1), two equivalent Na(3), and two equivalent Tb(2) atoms to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 4-12°. In the fifth O site, O(5) is bonded to two equivalent Na(1), two equivalent Na(3), and two equivalent Tb(2) atoms to form a mixture of edge and corner-sharing ONa4Tb2 octahedra. The corner-sharing octahedral tilt angles range from 2-6°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2TbO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.852
_cell_length_b   5.918
_cell_length_c   8.893
_cell_angle_alpha   70.912
_cell_angle_beta   72.388
_cell_angle_gamma   61.211
_symmetry_Int_Tables_number   1
_cell_volume   251.140
_cell_formula_units_Z   3
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  0.716  0.052  0.334  1.0
  Na  Na1  1  0.826  0.848  0.001  1.0
  Na  Na2  1  0.174  0.152  0.999  1.0
  Na  Na3  1  0.392  0.725  0.334  1.0
  Na  Na4  1  0.284  0.948  0.666  1.0
  Na  Na5  1  0.608  0.275  0.666  1.0
  Tb  Tb6  1  0.500  0.500  0.000  1.0
  Tb  Tb7  1  0.045  0.375  0.333  1.0
  Tb  Tb8  1  0.955  0.625  0.667  1.0
  O  O9  1  0.136  0.728  0.163  1.0
  O  O10  1  0.864  0.272  0.837  1.0
  O  O11  1  0.231  0.558  0.829  1.0
  O  O12  1  0.419  0.151  0.169  1.0
  O  O13  1  0.581  0.849  0.831  1.0
  O  O14  1  0.283  0.354  0.506  1.0
  O  O15  1  0.769  0.442  0.171  1.0
  O  O16  1  0.717  0.646  0.494  1.0
  O  O17  1  0.000  0.000  0.500  1.0
[/CIF]
.