The material structure described by Ba2Ta2O7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to six equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded to one O(5), three equivalent O(4), four equivalent O(1), and four equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, faces with four equivalent Ba(2)O12 cuboctahedra, faces with two equivalent Ta(1)O6 octahedra, and faces with six equivalent Ta(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, and faces with two equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-15°. In the second Ta site, Ta(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Ta(2)O6 octahedra, and faces with six equivalent Ba(2)O12 cuboctahedra. 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 four equivalent Ba(2) and two equivalent Ta(2) atoms to form a mixture of distorted face, corner, and edge-sharing OBa4Ta2 octahedra. The corner-sharing octahedral tilt angles are 60°. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ba(2), one Ta(1), and one Ta(2) atom. In the third O site, O(3) is bonded to three equivalent Ba(1) and one Ta(1) atom to form a mixture of distorted corner and edge-sharing OBa3Ta tetrahedra. In the fourth O site, O(4) is bonded in a distorted linear geometry to three equivalent Ba(2) and two equivalent Ta(2) atoms. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ba(2) and two equivalent Ta(1) atoms. is represented by the CIF file [CIF]
data_Ba2Ta2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.842
_cell_length_b   13.842
_cell_length_c   5.914
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   163.169
_symmetry_Int_Tables_number   1
_cell_volume   328.108
_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
  Ba  Ba0  1  0.703  0.297  0.750  1.0
  Ba  Ba1  1  0.553  0.447  0.250  1.0
  Ba  Ba2  1  0.297  0.703  0.250  1.0
  Ba  Ba3  1  0.447  0.553  0.750  1.0
  Ta  Ta4  1  0.838  0.162  0.750  1.0
  Ta  Ta5  1  0.943  0.057  0.250  1.0
  Ta  Ta6  1  0.162  0.838  0.250  1.0
  Ta  Ta7  1  0.057  0.943  0.750  1.0
  O  O8  1  0.000  0.000  0.500  1.0
  O  O9  1  0.899  0.101  0.497  1.0
  O  O10  1  0.000  0.000  0.000  1.0
  O  O11  1  0.899  0.101  0.003  1.0
  O  O12  1  0.793  0.207  0.523  1.0
  O  O13  1  0.793  0.207  0.977  1.0
  O  O14  1  0.550  0.450  0.750  1.0
  O  O15  1  0.652  0.348  0.250  1.0
  O  O16  1  0.450  0.550  0.250  1.0
  O  O17  1  0.207  0.793  0.023  1.0
  O  O18  1  0.207  0.793  0.477  1.0
  O  O19  1  0.101  0.899  0.503  1.0
  O  O20  1  0.348  0.652  0.750  1.0
  O  O21  1  0.101  0.899  0.997  1.0
[/CIF]
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The material structure described by Ba2Ta2O7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to six equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded to one O(5), three equivalent O(4), four equivalent O(1), and four equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, faces with four equivalent Ba(2)O12 cuboctahedra, faces with two equivalent Ta(1)O6 octahedra, and faces with six equivalent Ta(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, and faces with two equivalent Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-15°. In the second Ta site, Ta(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Ta(2)O6 octahedra, and faces with six equivalent Ba(2)O12 cuboctahedra. 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 four equivalent Ba(2) and two equivalent Ta(2) atoms to form a mixture of distorted face, corner, and edge-sharing OBa4Ta2 octahedra. The corner-sharing octahedral tilt angles are 60°. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ba(2), one Ta(1), and one Ta(2) atom. In the third O site, O(3) is bonded to three equivalent Ba(1) and one Ta(1) atom to form a mixture of distorted corner and edge-sharing OBa3Ta tetrahedra. In the fourth O site, O(4) is bonded in a distorted linear geometry to three equivalent Ba(2) and two equivalent Ta(2) atoms. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ba(2) and two equivalent Ta(1) atoms. is represented by the CIF file [CIF]
data_Ba2Ta2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.842
_cell_length_b   13.842
_cell_length_c   5.914
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   163.169
_symmetry_Int_Tables_number   1
_cell_volume   328.108
_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
  Ba  Ba0  1  0.703  0.297  0.750  1.0
  Ba  Ba1  1  0.553  0.447  0.250  1.0
  Ba  Ba2  1  0.297  0.703  0.250  1.0
  Ba  Ba3  1  0.447  0.553  0.750  1.0
  Ta  Ta4  1  0.838  0.162  0.750  1.0
  Ta  Ta5  1  0.943  0.057  0.250  1.0
  Ta  Ta6  1  0.162  0.838  0.250  1.0
  Ta  Ta7  1  0.057  0.943  0.750  1.0
  O  O8  1  0.000  0.000  0.500  1.0
  O  O9  1  0.899  0.101  0.497  1.0
  O  O10  1  0.000  0.000  0.000  1.0
  O  O11  1  0.899  0.101  0.003  1.0
  O  O12  1  0.793  0.207  0.523  1.0
  O  O13  1  0.793  0.207  0.977  1.0
  O  O14  1  0.550  0.450  0.750  1.0
  O  O15  1  0.652  0.348  0.250  1.0
  O  O16  1  0.450  0.550  0.250  1.0
  O  O17  1  0.207  0.793  0.023  1.0
  O  O18  1  0.207  0.793  0.477  1.0
  O  O19  1  0.101  0.899  0.503  1.0
  O  O20  1  0.348  0.652  0.750  1.0
  O  O21  1  0.101  0.899  0.997  1.0
[/CIF]
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