The crystal structure described by Na3Ca2TaO6 is Caswellsilverite-derived structured and crystallizes in the orthorhombic Fddd space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Ca(1)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, edges with four equivalent Ca(1)O6 octahedra, and edges with six equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-16°. In the second Na site, Na(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, edges with three equivalent Na(1)O6 octahedra, and edges with five equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-17°. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Ca(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with three equivalent Ta(1)O6 octahedra, and edges with five equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-18°. Ta(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with six equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), two equivalent Na(2), two equivalent Ca(1), and one Ta(1) atom to form a mixture of distorted corner and edge-sharing ONa3Ca2Ta octahedra. The corner-sharing octahedral tilt angles range from 0-12°. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), two equivalent Ca(1), and one Ta(1) atom to form a mixture of distorted corner and edge-sharing ONa3Ca2Ta octahedra. The corner-sharing octahedral tilt angles range from 2-12°. is represented by the CIF file [CIF]
data_Na3Ca2TaO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.994
_cell_length_b   10.440
_cell_length_c   5.833
_cell_angle_alpha   79.519
_cell_angle_beta   69.035
_cell_angle_gamma   31.446
_symmetry_Int_Tables_number   1
_cell_volume   315.496
_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  0.000  0.000  0.000  1.0
  Na  Na1  1  0.086  0.086  0.414  1.0
  Na  Na2  1  0.836  0.836  0.164  1.0
  Na  Na3  1  0.164  0.164  0.836  1.0
  Na  Na4  1  0.250  0.250  0.250  1.0
  Na  Na5  1  0.414  0.414  0.086  1.0
  Ca  Ca6  1  0.581  0.581  0.919  1.0
  Ca  Ca7  1  0.919  0.919  0.581  1.0
  Ca  Ca8  1  0.669  0.669  0.331  1.0
  Ca  Ca9  1  0.331  0.331  0.669  1.0
  Ta  Ta10  1  0.750  0.750  0.750  1.0
  Ta  Ta11  1  0.500  0.500  0.500  1.0
  O  O12  1  0.288  0.712  0.288  1.0
  O  O13  1  0.712  0.288  0.712  1.0
  O  O14  1  0.962  0.538  0.962  1.0
  O  O15  1  0.538  0.962  0.538  1.0
  O  O16  1  0.207  0.646  0.784  1.0
  O  O17  1  0.363  0.784  0.646  1.0
  O  O18  1  0.784  0.363  0.207  1.0
  O  O19  1  0.646  0.207  0.363  1.0
  O  O20  1  0.604  0.043  0.887  1.0
  O  O21  1  0.887  0.466  0.604  1.0
  O  O22  1  0.466  0.887  0.043  1.0
  O  O23  1  0.043  0.604  0.466  1.0
[/CIF]
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The crystal structure described by Na3Ca2TaO6 is Caswellsilverite-derived structured and crystallizes in the orthorhombic Fddd space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Ca(1)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, edges with four equivalent Ca(1)O6 octahedra, and edges with six equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-16°. In the second Na site, Na(2) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, edges with three equivalent Na(1)O6 octahedra, and edges with five equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-17°. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Na(2)O6 octahedra, corners with two equivalent Ca(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Ca(1)O6 octahedra, edges with three equivalent Ta(1)O6 octahedra, and edges with five equivalent Na(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 14-18°. Ta(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with six equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), two equivalent Na(2), two equivalent Ca(1), and one Ta(1) atom to form a mixture of distorted corner and edge-sharing ONa3Ca2Ta octahedra. The corner-sharing octahedral tilt angles range from 0-12°. In the second O site, O(2) is bonded to one Na(1), two equivalent Na(2), two equivalent Ca(1), and one Ta(1) atom to form a mixture of distorted corner and edge-sharing ONa3Ca2Ta octahedra. The corner-sharing octahedral tilt angles range from 2-12°. is represented by the CIF file [CIF]
data_Na3Ca2TaO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.994
_cell_length_b   10.440
_cell_length_c   5.833
_cell_angle_alpha   79.519
_cell_angle_beta   69.035
_cell_angle_gamma   31.446
_symmetry_Int_Tables_number   1
_cell_volume   315.496
_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  0.000  0.000  0.000  1.0
  Na  Na1  1  0.086  0.086  0.414  1.0
  Na  Na2  1  0.836  0.836  0.164  1.0
  Na  Na3  1  0.164  0.164  0.836  1.0
  Na  Na4  1  0.250  0.250  0.250  1.0
  Na  Na5  1  0.414  0.414  0.086  1.0
  Ca  Ca6  1  0.581  0.581  0.919  1.0
  Ca  Ca7  1  0.919  0.919  0.581  1.0
  Ca  Ca8  1  0.669  0.669  0.331  1.0
  Ca  Ca9  1  0.331  0.331  0.669  1.0
  Ta  Ta10  1  0.750  0.750  0.750  1.0
  Ta  Ta11  1  0.500  0.500  0.500  1.0
  O  O12  1  0.288  0.712  0.288  1.0
  O  O13  1  0.712  0.288  0.712  1.0
  O  O14  1  0.962  0.538  0.962  1.0
  O  O15  1  0.538  0.962  0.538  1.0
  O  O16  1  0.207  0.646  0.784  1.0
  O  O17  1  0.363  0.784  0.646  1.0
  O  O18  1  0.784  0.363  0.207  1.0
  O  O19  1  0.646  0.207  0.363  1.0
  O  O20  1  0.604  0.043  0.887  1.0
  O  O21  1  0.887  0.466  0.604  1.0
  O  O22  1  0.466  0.887  0.043  1.0
  O  O23  1  0.043  0.604  0.466  1.0
[/CIF]
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