The crystal structure described by Y2HfO5 crystallizes in the monoclinic C2/c space group. Y(1) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), and three equivalent O(1) atoms. Hf(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing HfO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are three inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Y(1) and one Hf(1) atom to form distorted OY3Hf trigonal pyramids that share  a cornercorner with one O(3)Y2Hf2 trigonal pyramid, corners with three equivalent O(1)Y3Hf trigonal pyramids, edges with two equivalent O(3)Y2Hf2 trigonal pyramids, and edges with two equivalent O(1)Y3Hf trigonal pyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Y(1) and one Hf(1) atom. In the third O site, O(3) is bonded to two equivalent Y(1) and two equivalent Hf(1) atoms to form distorted OY2Hf2 trigonal pyramids that share corners with two equivalent O(3)Y2Hf2 trigonal pyramids, corners with two equivalent O(1)Y3Hf trigonal pyramids, and edges with four equivalent O(1)Y3Hf trigonal pyramids. is represented by the CIF file [CIF]
data_Y2HfO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.520
_cell_length_b   6.520
_cell_length_c   7.697
_cell_angle_alpha   69.183
_cell_angle_beta   69.183
_cell_angle_gamma   50.164
_symmetry_Int_Tables_number   1
_cell_volume   231.068
_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
  Y  Y0  1  0.365  0.357  0.748  1.0
  Y  Y1  1  0.357  0.365  0.248  1.0
  Y  Y2  1  0.643  0.635  0.752  1.0
  Y  Y3  1  0.635  0.643  0.252  1.0
  Hf  Hf4  1  0.000  0.000  0.500  1.0
  Hf  Hf5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.251  0.601  0.956  1.0
  O  O7  1  0.601  0.251  0.456  1.0
  O  O8  1  0.977  0.675  0.645  1.0
  O  O9  1  0.325  0.023  0.855  1.0
  O  O10  1  0.675  0.977  0.145  1.0
  O  O11  1  0.023  0.325  0.355  1.0
  O  O12  1  0.399  0.749  0.544  1.0
  O  O13  1  0.824  0.176  0.750  1.0
  O  O14  1  0.749  0.399  0.044  1.0
  O  O15  1  0.176  0.824  0.250  1.0
[/CIF]
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The crystal structure described by Y2HfO5 crystallizes in the monoclinic C2/c space group. Y(1) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), and three equivalent O(1) atoms. Hf(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing HfO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are three inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Y(1) and one Hf(1) atom to form distorted OY3Hf trigonal pyramids that share  a cornercorner with one O(3)Y2Hf2 trigonal pyramid, corners with three equivalent O(1)Y3Hf trigonal pyramids, edges with two equivalent O(3)Y2Hf2 trigonal pyramids, and edges with two equivalent O(1)Y3Hf trigonal pyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Y(1) and one Hf(1) atom. In the third O site, O(3) is bonded to two equivalent Y(1) and two equivalent Hf(1) atoms to form distorted OY2Hf2 trigonal pyramids that share corners with two equivalent O(3)Y2Hf2 trigonal pyramids, corners with two equivalent O(1)Y3Hf trigonal pyramids, and edges with four equivalent O(1)Y3Hf trigonal pyramids. is represented by the CIF file [CIF]
data_Y2HfO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.520
_cell_length_b   6.520
_cell_length_c   7.697
_cell_angle_alpha   69.183
_cell_angle_beta   69.183
_cell_angle_gamma   50.164
_symmetry_Int_Tables_number   1
_cell_volume   231.068
_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
  Y  Y0  1  0.365  0.357  0.748  1.0
  Y  Y1  1  0.357  0.365  0.248  1.0
  Y  Y2  1  0.643  0.635  0.752  1.0
  Y  Y3  1  0.635  0.643  0.252  1.0
  Hf  Hf4  1  0.000  0.000  0.500  1.0
  Hf  Hf5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.251  0.601  0.956  1.0
  O  O7  1  0.601  0.251  0.456  1.0
  O  O8  1  0.977  0.675  0.645  1.0
  O  O9  1  0.325  0.023  0.855  1.0
  O  O10  1  0.675  0.977  0.145  1.0
  O  O11  1  0.023  0.325  0.355  1.0
  O  O12  1  0.399  0.749  0.544  1.0
  O  O13  1  0.824  0.176  0.750  1.0
  O  O14  1  0.749  0.399  0.044  1.0
  O  O15  1  0.176  0.824  0.250  1.0
[/CIF]
.