The material structure described by Ba2U2O7 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(1), two equivalent O(3), and four equivalent O(2) atoms to form distorted BaO8 hexagonal bipyramids that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with two equivalent U(2)O6 octahedra, edges with two equivalent U(2)O6 octahedra, and edges with four equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. In the second Ba site, Ba(2) is bonded in a distorted body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. There are two inequivalent U sites. In the first U site, U(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form UO6 octahedra that share corners with two equivalent U(1)O6 octahedra, corners with four equivalent U(2)O6 octahedra, and edges with four equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-43°. In the second U site, U(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form UO6 octahedra that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with four equivalent U(1)O6 octahedra, and edges with two equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 43°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(1) and two equivalent U(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one U(1), and one U(2) atom. In the third O site, O(3) is bonded to one Ba(1), two equivalent Ba(2), and one U(2) atom to form a mixture of distorted edge and corner-sharing OBa3U tetrahedra. is represented by the CIF card [CIF]
data_Ba2U2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.121
_cell_length_b   8.121
_cell_length_c   8.121
_cell_angle_alpha   119.443
_cell_angle_beta   118.974
_cell_angle_gamma   91.377
_symmetry_Int_Tables_number   1
_cell_volume   383.070
_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  1.000  0.000  1.000  1.0
  Ba  Ba1  1  0.500  0.500  1.000  1.0
  Ba  Ba2  1  0.500  1.000  1.000  1.0
  Ba  Ba3  1  0.500  0.500  0.500  1.0
  U  U4  1  0.000  0.000  0.500  1.0
  U  U5  1  1.000  0.500  0.500  1.0
  U  U6  1  0.000  0.500  0.000  1.0
  U  U7  1  0.500  1.000  0.500  1.0
  O  O8  1  0.911  0.750  0.161  1.0
  O  O9  1  0.688  0.915  0.365  1.0
  O  O10  1  0.621  0.907  0.714  1.0
  O  O11  1  0.688  0.323  0.772  1.0
  O  O12  1  0.312  0.677  0.228  1.0
  O  O13  1  0.312  0.085  0.635  1.0
  O  O14  1  0.693  0.407  0.286  1.0
  O  O15  1  0.051  0.823  0.635  1.0
  O  O16  1  0.051  0.415  0.228  1.0
  O  O17  1  0.089  0.250  0.839  1.0
  O  O18  1  0.379  0.093  0.286  1.0
  O  O19  1  0.949  0.177  0.365  1.0
  O  O20  1  0.949  0.585  0.772  1.0
  O  O21  1  0.307  0.593  0.714  1.0
[/CIF]
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The material structure described by Ba2U2O7 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(1), two equivalent O(3), and four equivalent O(2) atoms to form distorted BaO8 hexagonal bipyramids that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with two equivalent U(2)O6 octahedra, edges with two equivalent U(2)O6 octahedra, and edges with four equivalent U(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. In the second Ba site, Ba(2) is bonded in a distorted body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. There are two inequivalent U sites. In the first U site, U(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form UO6 octahedra that share corners with two equivalent U(1)O6 octahedra, corners with four equivalent U(2)O6 octahedra, and edges with four equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-43°. In the second U site, U(2) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form UO6 octahedra that share corners with two equivalent Ba(1)O8 hexagonal bipyramids, corners with four equivalent U(1)O6 octahedra, and edges with two equivalent Ba(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 43°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(1) and two equivalent U(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one U(1), and one U(2) atom. In the third O site, O(3) is bonded to one Ba(1), two equivalent Ba(2), and one U(2) atom to form a mixture of distorted edge and corner-sharing OBa3U tetrahedra. is represented by the CIF card [CIF]
data_Ba2U2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.121
_cell_length_b   8.121
_cell_length_c   8.121
_cell_angle_alpha   119.443
_cell_angle_beta   118.974
_cell_angle_gamma   91.377
_symmetry_Int_Tables_number   1
_cell_volume   383.070
_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  1.000  0.000  1.000  1.0
  Ba  Ba1  1  0.500  0.500  1.000  1.0
  Ba  Ba2  1  0.500  1.000  1.000  1.0
  Ba  Ba3  1  0.500  0.500  0.500  1.0
  U  U4  1  0.000  0.000  0.500  1.0
  U  U5  1  1.000  0.500  0.500  1.0
  U  U6  1  0.000  0.500  0.000  1.0
  U  U7  1  0.500  1.000  0.500  1.0
  O  O8  1  0.911  0.750  0.161  1.0
  O  O9  1  0.688  0.915  0.365  1.0
  O  O10  1  0.621  0.907  0.714  1.0
  O  O11  1  0.688  0.323  0.772  1.0
  O  O12  1  0.312  0.677  0.228  1.0
  O  O13  1  0.312  0.085  0.635  1.0
  O  O14  1  0.693  0.407  0.286  1.0
  O  O15  1  0.051  0.823  0.635  1.0
  O  O16  1  0.051  0.415  0.228  1.0
  O  O17  1  0.089  0.250  0.839  1.0
  O  O18  1  0.379  0.093  0.286  1.0
  O  O19  1  0.949  0.177  0.365  1.0
  O  O20  1  0.949  0.585  0.772  1.0
  O  O21  1  0.307  0.593  0.714  1.0
[/CIF]
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