The compound described by Y2HfO5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 8-coordinate geometry to one O(4), two equivalent O(1), two equivalent O(3), and three equivalent O(2) atoms. In the second Y site, Y(2) is bonded in a 7-coordinate geometry to one O(3), three equivalent O(4), and three equivalent O(5) atoms. Hf(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted corner-sharing HfO5 trigonal bipyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Y(1) and two equivalent Hf(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Y(1) and one Hf(1) atom. In the third O site, O(3) is bonded to one Y(2), two equivalent Y(1), and one Hf(1) atom to form OY3Hf tetrahedra that share  a cornercorner with one O(4)Y4 tetrahedra, corners with two equivalent O(3)Y3Hf tetrahedra, corners with two equivalent O(5)Y3Hf tetrahedra,  an edgeedge with one O(5)Y3Hf tetrahedra, and edges with two equivalent O(4)Y4 tetrahedra. In the fourth O site, O(4) is bonded to one Y(1) and three equivalent Y(2) atoms to form OY4 tetrahedra that share  a cornercorner with one O(3)Y3Hf tetrahedra, corners with four equivalent O(4)Y4 tetrahedra, corners with five equivalent O(5)Y3Hf tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(3)Y3Hf tetrahedra, and edges with two equivalent O(5)Y3Hf tetrahedra. In the fifth O site, O(5) is bonded to three 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 four equivalent O(5)Y3Hf tetrahedra, corners with five equivalent O(4)Y4 tetrahedra,  an edgeedge with one O(3)Y3Hf tetrahedra,  an edgeedge with one O(5)Y3Hf tetrahedra, and edges with two equivalent O(4)Y4 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2HfO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.234
_cell_length_b   6.512
_cell_length_c   9.688
_cell_angle_alpha   75.266
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   441.339
_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  0.637  0.029  0.147  1.0
  Y  Y1  1  0.863  0.529  0.147  1.0
  Y  Y2  1  0.624  0.239  0.469  1.0
  Y  Y3  1  0.124  0.261  0.531  1.0
  Y  Y4  1  0.876  0.739  0.469  1.0
  Y  Y5  1  0.376  0.761  0.531  1.0
  Y  Y6  1  0.137  0.471  0.853  1.0
  Y  Y7  1  0.363  0.971  0.853  1.0
  Hf  Hf8  1  0.111  0.061  0.189  1.0
  Hf  Hf9  1  0.389  0.561  0.189  1.0
  Hf  Hf10  1  0.611  0.439  0.811  1.0
  Hf  Hf11  1  0.889  0.939  0.811  1.0
  O  O12  1  0.323  0.889  0.152  1.0
  O  O13  1  0.894  0.229  0.065  1.0
  O  O14  1  0.177  0.389  0.152  1.0
  O  O15  1  0.590  0.336  0.224  1.0
  O  O16  1  0.606  0.729  0.065  1.0
  O  O17  1  0.910  0.836  0.224  1.0
  O  O18  1  0.888  0.425  0.390  1.0
  O  O19  1  0.363  0.495  0.398  1.0
  O  O20  1  0.612  0.925  0.390  1.0
  O  O21  1  0.137  0.995  0.398  1.0
  O  O22  1  0.863  0.005  0.602  1.0
  O  O23  1  0.388  0.075  0.610  1.0
  O  O24  1  0.637  0.505  0.602  1.0
  O  O25  1  0.112  0.575  0.610  1.0
  O  O26  1  0.090  0.164  0.776  1.0
  O  O27  1  0.394  0.271  0.935  1.0
  O  O28  1  0.410  0.664  0.776  1.0
  O  O29  1  0.823  0.611  0.848  1.0
  O  O30  1  0.106  0.771  0.935  1.0
  O  O31  1  0.677  0.111  0.848  1.0
[/CIF]
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The compound described by Y2HfO5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 8-coordinate geometry to one O(4), two equivalent O(1), two equivalent O(3), and three equivalent O(2) atoms. In the second Y site, Y(2) is bonded in a 7-coordinate geometry to one O(3), three equivalent O(4), and three equivalent O(5) atoms. Hf(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted corner-sharing HfO5 trigonal bipyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Y(1) and two equivalent Hf(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Y(1) and one Hf(1) atom. In the third O site, O(3) is bonded to one Y(2), two equivalent Y(1), and one Hf(1) atom to form OY3Hf tetrahedra that share  a cornercorner with one O(4)Y4 tetrahedra, corners with two equivalent O(3)Y3Hf tetrahedra, corners with two equivalent O(5)Y3Hf tetrahedra,  an edgeedge with one O(5)Y3Hf tetrahedra, and edges with two equivalent O(4)Y4 tetrahedra. In the fourth O site, O(4) is bonded to one Y(1) and three equivalent Y(2) atoms to form OY4 tetrahedra that share  a cornercorner with one O(3)Y3Hf tetrahedra, corners with four equivalent O(4)Y4 tetrahedra, corners with five equivalent O(5)Y3Hf tetrahedra,  an edgeedge with one O(4)Y4 tetrahedra, edges with two equivalent O(3)Y3Hf tetrahedra, and edges with two equivalent O(5)Y3Hf tetrahedra. In the fifth O site, O(5) is bonded to three 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 four equivalent O(5)Y3Hf tetrahedra, corners with five equivalent O(4)Y4 tetrahedra,  an edgeedge with one O(3)Y3Hf tetrahedra,  an edgeedge with one O(5)Y3Hf tetrahedra, and edges with two equivalent O(4)Y4 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2HfO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.234
_cell_length_b   6.512
_cell_length_c   9.688
_cell_angle_alpha   75.266
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   441.339
_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  0.637  0.029  0.147  1.0
  Y  Y1  1  0.863  0.529  0.147  1.0
  Y  Y2  1  0.624  0.239  0.469  1.0
  Y  Y3  1  0.124  0.261  0.531  1.0
  Y  Y4  1  0.876  0.739  0.469  1.0
  Y  Y5  1  0.376  0.761  0.531  1.0
  Y  Y6  1  0.137  0.471  0.853  1.0
  Y  Y7  1  0.363  0.971  0.853  1.0
  Hf  Hf8  1  0.111  0.061  0.189  1.0
  Hf  Hf9  1  0.389  0.561  0.189  1.0
  Hf  Hf10  1  0.611  0.439  0.811  1.0
  Hf  Hf11  1  0.889  0.939  0.811  1.0
  O  O12  1  0.323  0.889  0.152  1.0
  O  O13  1  0.894  0.229  0.065  1.0
  O  O14  1  0.177  0.389  0.152  1.0
  O  O15  1  0.590  0.336  0.224  1.0
  O  O16  1  0.606  0.729  0.065  1.0
  O  O17  1  0.910  0.836  0.224  1.0
  O  O18  1  0.888  0.425  0.390  1.0
  O  O19  1  0.363  0.495  0.398  1.0
  O  O20  1  0.612  0.925  0.390  1.0
  O  O21  1  0.137  0.995  0.398  1.0
  O  O22  1  0.863  0.005  0.602  1.0
  O  O23  1  0.388  0.075  0.610  1.0
  O  O24  1  0.637  0.505  0.602  1.0
  O  O25  1  0.112  0.575  0.610  1.0
  O  O26  1  0.090  0.164  0.776  1.0
  O  O27  1  0.394  0.271  0.935  1.0
  O  O28  1  0.410  0.664  0.776  1.0
  O  O29  1  0.823  0.611  0.848  1.0
  O  O30  1  0.106  0.771  0.935  1.0
  O  O31  1  0.677  0.111  0.848  1.0
[/CIF]
.