The compound described by Ba3Hf2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, and faces with eight equivalent Hf(1)O6 octahedra. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to four equivalent O(2) and five equivalent O(3) atoms. Hf(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form HfO6 octahedra that share corners with five equivalent Hf(1)O6 octahedra and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-1°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to four equivalent Ba(1) and two equivalent Hf(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Hf(1) atoms. In the third O site, O(3) is bonded to five equivalent Ba(2) and one Hf(1) atom to form a mixture of distorted corner and edge-sharing OBa5Hf octahedra. The corner-sharing octahedral tilt angles are 4°. is represented by the CIF card [CIF]
data_Ba3Hf2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.166
_cell_length_b   11.332
_cell_length_c   4.166
_cell_angle_alpha   79.407
_cell_angle_beta   90.000
_cell_angle_gamma   100.593
_symmetry_Int_Tables_number   1
_cell_volume   189.904
_cell_formula_units_Z   1
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  0.500  0.000  0.500  1.0
  Ba  Ba1  1  0.686  0.372  0.314  1.0
  Ba  Ba2  1  0.314  0.628  0.686  1.0
  Hf  Hf3  1  0.904  0.807  0.096  1.0
  Hf  Hf4  1  0.096  0.193  0.904  1.0
  O  O5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.096  0.191  0.404  1.0
  O  O7  1  0.404  0.809  0.096  1.0
  O  O8  1  0.809  0.618  0.191  1.0
  O  O9  1  0.191  0.382  0.809  1.0
  O  O10  1  0.596  0.191  0.904  1.0
  O  O11  1  0.904  0.809  0.596  1.0
[/CIF]
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The compound described by Ba3Hf2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, and faces with eight equivalent Hf(1)O6 octahedra. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to four equivalent O(2) and five equivalent O(3) atoms. Hf(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form HfO6 octahedra that share corners with five equivalent Hf(1)O6 octahedra and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-1°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to four equivalent Ba(1) and two equivalent Hf(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Hf(1) atoms. In the third O site, O(3) is bonded to five equivalent Ba(2) and one Hf(1) atom to form a mixture of distorted corner and edge-sharing OBa5Hf octahedra. The corner-sharing octahedral tilt angles are 4°. is represented by the CIF card [CIF]
data_Ba3Hf2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.166
_cell_length_b   11.332
_cell_length_c   4.166
_cell_angle_alpha   79.407
_cell_angle_beta   90.000
_cell_angle_gamma   100.593
_symmetry_Int_Tables_number   1
_cell_volume   189.904
_cell_formula_units_Z   1
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  0.500  0.000  0.500  1.0
  Ba  Ba1  1  0.686  0.372  0.314  1.0
  Ba  Ba2  1  0.314  0.628  0.686  1.0
  Hf  Hf3  1  0.904  0.807  0.096  1.0
  Hf  Hf4  1  0.096  0.193  0.904  1.0
  O  O5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.096  0.191  0.404  1.0
  O  O7  1  0.404  0.809  0.096  1.0
  O  O8  1  0.809  0.618  0.191  1.0
  O  O9  1  0.191  0.382  0.809  1.0
  O  O10  1  0.596  0.191  0.904  1.0
  O  O11  1  0.904  0.809  0.596  1.0
[/CIF]
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