The material described by Y2HfO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(3), one O(5), two equivalent O(1), and three equivalent O(4) atoms. In the second Y site, Y(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form YO6 octahedra that share corners with two equivalent Y(2)O6 octahedra, corners with four equivalent Hf(1)O6 octahedra, and edges with two equivalent Y(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. Hf(1) is bonded to one O(3), one O(4), one O(5), and three equivalent O(2) atoms to form distorted HfO6 octahedra that share corners with two equivalent Hf(1)O6 octahedra, corners with four equivalent Y(2)O6 octahedra, and edges with two equivalent Hf(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-62°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(3)Y3Hf tetrahedra, corners with four equivalent O(4)Y3Hf tetrahedra, corners with four equivalent O(1)Y4 tetrahedra, corners with two equivalent O(5)Y3Hf trigonal pyramids,  an edgeedge with one O(4)Y3Hf tetrahedra, edges with two equivalent O(3)Y3Hf tetrahedra, and edges with two equivalent O(5)Y3Hf trigonal pyramids. In the second O site, O(2) is bonded in a 3-coordinate geometry to three equivalent Hf(1) atoms. In the third O site, O(3) is bonded to one Y(1), two equivalent Y(2), and one Hf(1) atom to form distorted OY3Hf tetrahedra that share corners with two equivalent O(3)Y3Hf tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(4)Y3Hf tetrahedra, corners with four equivalent O(5)Y3Hf trigonal pyramids, edges with two equivalent O(1)Y4 tetrahedra, and  an edgeedge with one O(5)Y3Hf trigonal pyramid. In the fourth O site, O(4) is bonded to three equivalent Y(1) and one Hf(1) atom to form OY3Hf tetrahedra that share corners with two equivalent O(4)Y3Hf tetrahedra, corners with four equivalent O(3)Y3Hf tetrahedra, corners with four equivalent O(1)Y4 tetrahedra, corners with two equivalent O(5)Y3Hf trigonal pyramids,  an edgeedge with one O(1)Y4 tetrahedra, edges with two equivalent O(4)Y3Hf tetrahedra, and  an edgeedge with one O(5)Y3Hf trigonal pyramid. In the fifth O site, O(5) is bonded to one Y(1), two equivalent Y(2), and one Hf(1) atom to form distorted OY3Hf trigonal pyramids that share corners with two equivalent O(4)Y3Hf tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(3)Y3Hf tetrahedra, corners with two equivalent O(5)Y3Hf trigonal pyramids,  an edgeedge with one O(3)Y3Hf tetrahedra,  an edgeedge with one O(4)Y3Hf tetrahedra, and edges with two equivalent O(1)Y4 tetrahedra. is represented by the CIF file [CIF]
data_Y2HfO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.734
_cell_length_b   7.461
_cell_length_c   15.650
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   436.064
_cell_formula_units_Z   4
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  0.250  0.094  0.089  1.0
  Y  Y1  1  0.250  0.141  0.740  1.0
  Y  Y2  1  0.750  0.359  0.240  1.0
  Y  Y3  1  0.750  0.406  0.589  1.0
  Y  Y4  1  0.250  0.594  0.411  1.0
  Y  Y5  1  0.250  0.641  0.760  1.0
  Y  Y6  1  0.750  0.859  0.260  1.0
  Y  Y7  1  0.750  0.906  0.911  1.0
  Hf  Hf8  1  0.250  0.124  0.428  1.0
  Hf  Hf9  1  0.750  0.376  0.928  1.0
  Hf  Hf10  1  0.250  0.624  0.072  1.0
  Hf  Hf11  1  0.750  0.876  0.572  1.0
  O  O12  1  0.750  0.097  0.179  1.0
  O  O13  1  0.750  0.090  0.466  1.0
  O  O14  1  0.750  0.097  0.653  1.0
  O  O15  1  0.750  0.143  0.004  1.0
  O  O16  1  0.250  0.298  0.330  1.0
  O  O17  1  0.750  0.202  0.830  1.0
  O  O18  1  0.250  0.357  0.504  1.0
  O  O19  1  0.250  0.403  0.153  1.0
  O  O20  1  0.250  0.410  0.966  1.0
  O  O21  1  0.250  0.403  0.679  1.0
  O  O22  1  0.750  0.597  0.321  1.0
  O  O23  1  0.750  0.590  0.034  1.0
  O  O24  1  0.750  0.597  0.847  1.0
  O  O25  1  0.750  0.643  0.496  1.0
  O  O26  1  0.250  0.798  0.170  1.0
  O  O27  1  0.750  0.702  0.670  1.0
  O  O28  1  0.250  0.857  0.996  1.0
  O  O29  1  0.250  0.903  0.347  1.0
  O  O30  1  0.250  0.910  0.534  1.0
  O  O31  1  0.250  0.903  0.821  1.0
[/CIF]
.
The material described by Y2HfO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(3), one O(5), two equivalent O(1), and three equivalent O(4) atoms. In the second Y site, Y(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms to form YO6 octahedra that share corners with two equivalent Y(2)O6 octahedra, corners with four equivalent Hf(1)O6 octahedra, and edges with two equivalent Y(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 55-62°. Hf(1) is bonded to one O(3), one O(4), one O(5), and three equivalent O(2) atoms to form distorted HfO6 octahedra that share corners with two equivalent Hf(1)O6 octahedra, corners with four equivalent Y(2)O6 octahedra, and edges with two equivalent Hf(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-62°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Y(1) and two equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(3)Y3Hf tetrahedra, corners with four equivalent O(4)Y3Hf tetrahedra, corners with four equivalent O(1)Y4 tetrahedra, corners with two equivalent O(5)Y3Hf trigonal pyramids,  an edgeedge with one O(4)Y3Hf tetrahedra, edges with two equivalent O(3)Y3Hf tetrahedra, and edges with two equivalent O(5)Y3Hf trigonal pyramids. In the second O site, O(2) is bonded in a 3-coordinate geometry to three equivalent Hf(1) atoms. In the third O site, O(3) is bonded to one Y(1), two equivalent Y(2), and one Hf(1) atom to form distorted OY3Hf tetrahedra that share corners with two equivalent O(3)Y3Hf tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(4)Y3Hf tetrahedra, corners with four equivalent O(5)Y3Hf trigonal pyramids, edges with two equivalent O(1)Y4 tetrahedra, and  an edgeedge with one O(5)Y3Hf trigonal pyramid. In the fourth O site, O(4) is bonded to three equivalent Y(1) and one Hf(1) atom to form OY3Hf tetrahedra that share corners with two equivalent O(4)Y3Hf tetrahedra, corners with four equivalent O(3)Y3Hf tetrahedra, corners with four equivalent O(1)Y4 tetrahedra, corners with two equivalent O(5)Y3Hf trigonal pyramids,  an edgeedge with one O(1)Y4 tetrahedra, edges with two equivalent O(4)Y3Hf tetrahedra, and  an edgeedge with one O(5)Y3Hf trigonal pyramid. In the fifth O site, O(5) is bonded to one Y(1), two equivalent Y(2), and one Hf(1) atom to form distorted OY3Hf trigonal pyramids that share corners with two equivalent O(4)Y3Hf tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with four equivalent O(3)Y3Hf tetrahedra, corners with two equivalent O(5)Y3Hf trigonal pyramids,  an edgeedge with one O(3)Y3Hf tetrahedra,  an edgeedge with one O(4)Y3Hf tetrahedra, and edges with two equivalent O(1)Y4 tetrahedra. is represented by the CIF file [CIF]
data_Y2HfO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.734
_cell_length_b   7.461
_cell_length_c   15.650
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   436.064
_cell_formula_units_Z   4
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  0.250  0.094  0.089  1.0
  Y  Y1  1  0.250  0.141  0.740  1.0
  Y  Y2  1  0.750  0.359  0.240  1.0
  Y  Y3  1  0.750  0.406  0.589  1.0
  Y  Y4  1  0.250  0.594  0.411  1.0
  Y  Y5  1  0.250  0.641  0.760  1.0
  Y  Y6  1  0.750  0.859  0.260  1.0
  Y  Y7  1  0.750  0.906  0.911  1.0
  Hf  Hf8  1  0.250  0.124  0.428  1.0
  Hf  Hf9  1  0.750  0.376  0.928  1.0
  Hf  Hf10  1  0.250  0.624  0.072  1.0
  Hf  Hf11  1  0.750  0.876  0.572  1.0
  O  O12  1  0.750  0.097  0.179  1.0
  O  O13  1  0.750  0.090  0.466  1.0
  O  O14  1  0.750  0.097  0.653  1.0
  O  O15  1  0.750  0.143  0.004  1.0
  O  O16  1  0.250  0.298  0.330  1.0
  O  O17  1  0.750  0.202  0.830  1.0
  O  O18  1  0.250  0.357  0.504  1.0
  O  O19  1  0.250  0.403  0.153  1.0
  O  O20  1  0.250  0.410  0.966  1.0
  O  O21  1  0.250  0.403  0.679  1.0
  O  O22  1  0.750  0.597  0.321  1.0
  O  O23  1  0.750  0.590  0.034  1.0
  O  O24  1  0.750  0.597  0.847  1.0
  O  O25  1  0.750  0.643  0.496  1.0
  O  O26  1  0.250  0.798  0.170  1.0
  O  O27  1  0.750  0.702  0.670  1.0
  O  O28  1  0.250  0.857  0.996  1.0
  O  O29  1  0.250  0.903  0.347  1.0
  O  O30  1  0.250  0.910  0.534  1.0
  O  O31  1  0.250  0.903  0.821  1.0
[/CIF]
.