The compound described by Sr3Hf2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Hf(1)O6 octahedra. In the second Sr site, Sr(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 Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to four equivalent Sr(1) and two equivalent Hf(1) atoms. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Hf(1) atoms to form distorted OSr4Hf2 octahedra that share corners with six equivalent O(3)Sr5Hf octahedra, corners with eight equivalent O(2)Sr4Hf2 octahedra, edges with three equivalent O(2)Sr4Hf2 octahedra, faces with two equivalent O(3)Sr5Hf octahedra, and faces with four equivalent O(2)Sr4Hf2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the third O site, O(3) is bonded to five equivalent Sr(2) and one Hf(1) atom to form distorted OSr5Hf octahedra that share corners with four equivalent O(3)Sr5Hf octahedra, corners with twelve equivalent O(2)Sr4Hf2 octahedra, edges with eight equivalent O(3)Sr5Hf octahedra, and faces with four equivalent O(2)Sr4Hf2 octahedra. The corner-sharing octahedral tilt angles range from 10-55°. is represented by the CIF file [CIF]
data_Sr3Hf2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.915
_cell_length_b   10.915
_cell_length_c   10.915
_cell_angle_alpha   158.179
_cell_angle_beta   158.179
_cell_angle_gamma   31.052
_symmetry_Int_Tables_number   1
_cell_volume   179.532
_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
  Sr  Sr0  1  0.500  0.500  0.000  1.0
  Sr  Sr1  1  0.687  0.687  0.000  1.0
  Sr  Sr2  1  0.313  0.313  0.000  1.0
  Hf  Hf3  1  0.901  0.901  0.000  1.0
  Hf  Hf4  1  0.099  0.099  0.000  1.0
  O  O5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.098  0.598  0.500  1.0
  O  O7  1  0.402  0.902  0.500  1.0
  O  O8  1  0.802  0.802  0.000  1.0
  O  O9  1  0.198  0.198  0.000  1.0
  O  O10  1  0.598  0.098  0.500  1.0
  O  O11  1  0.902  0.402  0.500  1.0
[/CIF]
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The compound described by Sr3Hf2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Hf(1)O6 octahedra. In the second Sr site, Sr(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 Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to four equivalent Sr(1) and two equivalent Hf(1) atoms. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Hf(1) atoms to form distorted OSr4Hf2 octahedra that share corners with six equivalent O(3)Sr5Hf octahedra, corners with eight equivalent O(2)Sr4Hf2 octahedra, edges with three equivalent O(2)Sr4Hf2 octahedra, faces with two equivalent O(3)Sr5Hf octahedra, and faces with four equivalent O(2)Sr4Hf2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the third O site, O(3) is bonded to five equivalent Sr(2) and one Hf(1) atom to form distorted OSr5Hf octahedra that share corners with four equivalent O(3)Sr5Hf octahedra, corners with twelve equivalent O(2)Sr4Hf2 octahedra, edges with eight equivalent O(3)Sr5Hf octahedra, and faces with four equivalent O(2)Sr4Hf2 octahedra. The corner-sharing octahedral tilt angles range from 10-55°. is represented by the CIF file [CIF]
data_Sr3Hf2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.915
_cell_length_b   10.915
_cell_length_c   10.915
_cell_angle_alpha   158.179
_cell_angle_beta   158.179
_cell_angle_gamma   31.052
_symmetry_Int_Tables_number   1
_cell_volume   179.532
_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
  Sr  Sr0  1  0.500  0.500  0.000  1.0
  Sr  Sr1  1  0.687  0.687  0.000  1.0
  Sr  Sr2  1  0.313  0.313  0.000  1.0
  Hf  Hf3  1  0.901  0.901  0.000  1.0
  Hf  Hf4  1  0.099  0.099  0.000  1.0
  O  O5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.098  0.598  0.500  1.0
  O  O7  1  0.402  0.902  0.500  1.0
  O  O8  1  0.802  0.802  0.000  1.0
  O  O9  1  0.198  0.198  0.000  1.0
  O  O10  1  0.598  0.098  0.500  1.0
  O  O11  1  0.902  0.402  0.500  1.0
[/CIF]
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