The material structure described by Ba2Ta2O7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms to form distorted BaO8 hexagonal bipyramids that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with two equivalent Ta(2)O6 octahedra, edges with four equivalent Ba(2)O8 hexagonal bipyramids, edges with two equivalent Ta(2)O6 octahedra, and edges with four equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. In the second Ba site, Ba(2) is bonded to four equivalent O(1) and four equivalent O(2) atoms to form distorted BaO8 hexagonal bipyramids that share edges with two equivalent Ba(2)O8 hexagonal bipyramids, edges with four equivalent Ba(1)O8 hexagonal bipyramids, edges with two equivalent Ta(1)O6 octahedra, and edges with four equivalent Ta(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Ta(2)O6 octahedra, edges with two equivalent Ba(2)O8 hexagonal bipyramids, and edges with four equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 35-39°. In the second Ta site, Ta(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form TaO6 octahedra that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with four equivalent Ta(1)O6 octahedra, edges with two equivalent Ba(1)O8 hexagonal bipyramids, and edges with four equivalent Ba(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 35°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded to one Ba(1), two equivalent Ba(2), and one Ta(2) atom to form a mixture of distorted edge and corner-sharing OBa3Ta tetrahedra. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(1) and two equivalent Ta(1) atoms. is represented by the CIF card [CIF]
data_Ba2Ta2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.780
_cell_length_b   7.780
_cell_length_c   7.780
_cell_angle_alpha   120.448
_cell_angle_beta   117.467
_cell_angle_gamma   91.835
_symmetry_Int_Tables_number   1
_cell_volume   337.709
_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  0.000  0.000  0.000  1.0
  Ba  Ba1  1  0.500  0.500  0.000  1.0
  Ba  Ba2  1  0.000  0.500  0.000  1.0
  Ba  Ba3  1  0.000  0.000  0.500  1.0
  Ta  Ta4  1  0.500  0.000  0.000  1.0
  Ta  Ta5  1  0.500  0.000  0.500  1.0
  Ta  Ta6  1  0.500  0.500  0.500  1.0
  Ta  Ta7  1  0.000  0.500  0.500  1.0
  O  O8  1  0.799  0.192  0.228  1.0
  O  O9  1  0.800  0.090  0.710  1.0
  O  O10  1  0.416  0.250  0.166  1.0
  O  O11  1  0.881  0.590  0.290  1.0
  O  O12  1  0.536  0.308  0.607  1.0
  O  O13  1  0.464  0.071  0.772  1.0
  O  O14  1  0.799  0.571  0.607  1.0
  O  O15  1  0.201  0.429  0.393  1.0
  O  O16  1  0.464  0.692  0.393  1.0
  O  O17  1  0.536  0.929  0.228  1.0
  O  O18  1  0.119  0.410  0.710  1.0
  O  O19  1  0.584  0.750  0.834  1.0
  O  O20  1  0.200  0.910  0.290  1.0
  O  O21  1  0.201  0.808  0.772  1.0
[/CIF]
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The material structure described by Ba2Ta2O7 crystallizes in the orthorhombic Imma space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms to form distorted BaO8 hexagonal bipyramids that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with two equivalent Ta(2)O6 octahedra, edges with four equivalent Ba(2)O8 hexagonal bipyramids, edges with two equivalent Ta(2)O6 octahedra, and edges with four equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles are 53°. In the second Ba site, Ba(2) is bonded to four equivalent O(1) and four equivalent O(2) atoms to form distorted BaO8 hexagonal bipyramids that share edges with two equivalent Ba(2)O8 hexagonal bipyramids, edges with four equivalent Ba(1)O8 hexagonal bipyramids, edges with two equivalent Ta(1)O6 octahedra, and edges with four equivalent Ta(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Ta(2)O6 octahedra, edges with two equivalent Ba(2)O8 hexagonal bipyramids, and edges with four equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 35-39°. In the second Ta site, Ta(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form TaO6 octahedra that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with four equivalent Ta(1)O6 octahedra, edges with two equivalent Ba(1)O8 hexagonal bipyramids, and edges with four equivalent Ba(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 35°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded to one Ba(1), two equivalent Ba(2), and one Ta(2) atom to form a mixture of distorted edge and corner-sharing OBa3Ta tetrahedra. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(1) and two equivalent Ta(1) atoms. is represented by the CIF card [CIF]
data_Ba2Ta2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.780
_cell_length_b   7.780
_cell_length_c   7.780
_cell_angle_alpha   120.448
_cell_angle_beta   117.467
_cell_angle_gamma   91.835
_symmetry_Int_Tables_number   1
_cell_volume   337.709
_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  0.000  0.000  0.000  1.0
  Ba  Ba1  1  0.500  0.500  0.000  1.0
  Ba  Ba2  1  0.000  0.500  0.000  1.0
  Ba  Ba3  1  0.000  0.000  0.500  1.0
  Ta  Ta4  1  0.500  0.000  0.000  1.0
  Ta  Ta5  1  0.500  0.000  0.500  1.0
  Ta  Ta6  1  0.500  0.500  0.500  1.0
  Ta  Ta7  1  0.000  0.500  0.500  1.0
  O  O8  1  0.799  0.192  0.228  1.0
  O  O9  1  0.800  0.090  0.710  1.0
  O  O10  1  0.416  0.250  0.166  1.0
  O  O11  1  0.881  0.590  0.290  1.0
  O  O12  1  0.536  0.308  0.607  1.0
  O  O13  1  0.464  0.071  0.772  1.0
  O  O14  1  0.799  0.571  0.607  1.0
  O  O15  1  0.201  0.429  0.393  1.0
  O  O16  1  0.464  0.692  0.393  1.0
  O  O17  1  0.536  0.929  0.228  1.0
  O  O18  1  0.119  0.410  0.710  1.0
  O  O19  1  0.584  0.750  0.834  1.0
  O  O20  1  0.200  0.910  0.290  1.0
  O  O21  1  0.201  0.808  0.772  1.0
[/CIF]
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