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 to one O(1), one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(2)O7 hexagonal pyramids, corners with three equivalent Hf(1)O5 trigonal bipyramids, edges with two equivalent Y(1)O7 hexagonal pyramids, edges with three equivalent Y(2)O7 hexagonal pyramids, and edges with two equivalent Hf(1)O5 trigonal bipyramids. In the second Y site, Y(2) is bonded to one O(4), one O(5), two equivalent O(3), and three equivalent O(1) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(1)O7 hexagonal pyramids,  a cornercorner with one Hf(1)O5 trigonal bipyramid, edges with three equivalent Y(1)O7 hexagonal pyramids, edges with four equivalent Y(2)O7 hexagonal pyramids, and edges with two equivalent Hf(1)O5 trigonal bipyramids. Hf(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted HfO5 trigonal bipyramids that share  a cornercorner with one Y(2)O7 hexagonal pyramid, corners with three equivalent Y(1)O7 hexagonal pyramids, corners with two equivalent Hf(1)O5 trigonal bipyramids, edges with two equivalent Y(1)O7 hexagonal pyramids, and edges with two equivalent Y(2)O7 hexagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Y(1) and three equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(4)Y2Hf2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with five equivalent O(3)Y3Hf tetrahedra, corners with five equivalent O(5)Y3Hf tetrahedra,  an edgeedge with one O(4)Y2Hf2 tetrahedra,  an edgeedge with one O(3)Y3Hf tetrahedra, and edges with two equivalent O(1)Y4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Y(1) and one Hf(1) atom. In the third O site, O(3) is bonded to one Y(1), two equivalent Y(2), and one Hf(1) atom to form OY3Hf tetrahedra that share  a cornercorner with one O(4)Y2Hf2 tetrahedra,  a cornercorner with one O(5)Y3Hf tetrahedra, corners with two equivalent O(3)Y3Hf tetrahedra, corners with five equivalent O(1)Y4 tetrahedra,  an edgeedge with one O(1)Y4 tetrahedra, edges with two equivalent O(4)Y2Hf2 tetrahedra, and edges with two equivalent O(5)Y3Hf tetrahedra. In the fourth O site, O(4) is bonded to one Y(1), one Y(2), and two equivalent Hf(1) atoms to form OY2Hf2 tetrahedra that share  a cornercorner with one O(3)Y3Hf tetrahedra,  a cornercorner with one O(5)Y3Hf tetrahedra, corners with two equivalent O(4)Y2Hf2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra,  an edgeedge with one O(1)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 one Y(2), two equivalent Y(1), and one Hf(1) atom to form OY3Hf tetrahedra that share  a cornercorner with one O(4)Y2Hf2 tetrahedra,  a cornercorner with one O(3)Y3Hf tetrahedra, corners with two equivalent O(5)Y3Hf tetrahedra, corners with five equivalent O(1)Y4 tetrahedra, edges with two equivalent O(4)Y2Hf2 tetrahedra, and edges with two equivalent O(3)Y3Hf tetrahedra. is represented by the CIF file [CIF]
data_Y2HfO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.744
_cell_length_b   10.755
_cell_length_c   11.630
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   468.332
_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  0.122  0.224  1.0
  Y  Y1  1  0.250  0.130  0.561  1.0
  Y  Y2  1  0.750  0.370  0.061  1.0
  Y  Y3  1  0.750  0.378  0.724  1.0
  Y  Y4  1  0.250  0.622  0.276  1.0
  Y  Y5  1  0.250  0.630  0.939  1.0
  Y  Y6  1  0.750  0.870  0.439  1.0
  Y  Y7  1  0.750  0.878  0.776  1.0
  Hf  Hf8  1  0.250  0.170  0.886  1.0
  Hf  Hf9  1  0.750  0.330  0.386  1.0
  Hf  Hf10  1  0.250  0.670  0.614  1.0
  Hf  Hf11  1  0.750  0.830  0.114  1.0
  O  O12  1  0.750  0.004  0.605  1.0
  O  O13  1  0.250  0.995  0.844  1.0
  O  O14  1  0.250  0.230  0.051  1.0
  O  O15  1  0.750  0.245  0.889  1.0
  O  O16  1  0.750  0.249  0.229  1.0
  O  O17  1  0.250  0.251  0.729  1.0
  O  O18  1  0.250  0.255  0.389  1.0
  O  O19  1  0.750  0.270  0.551  1.0
  O  O20  1  0.750  0.505  0.344  1.0
  O  O21  1  0.250  0.496  0.105  1.0
  O  O22  1  0.750  0.504  0.895  1.0
  O  O23  1  0.250  0.495  0.656  1.0
  O  O24  1  0.250  0.730  0.449  1.0
  O  O25  1  0.750  0.745  0.611  1.0
  O  O26  1  0.750  0.749  0.271  1.0
  O  O27  1  0.250  0.751  0.771  1.0
  O  O28  1  0.250  0.755  0.111  1.0
  O  O29  1  0.750  0.770  0.949  1.0
  O  O30  1  0.750  0.005  0.156  1.0
  O  O31  1  0.250  0.996  0.395  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 to one O(1), one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(2)O7 hexagonal pyramids, corners with three equivalent Hf(1)O5 trigonal bipyramids, edges with two equivalent Y(1)O7 hexagonal pyramids, edges with three equivalent Y(2)O7 hexagonal pyramids, and edges with two equivalent Hf(1)O5 trigonal bipyramids. In the second Y site, Y(2) is bonded to one O(4), one O(5), two equivalent O(3), and three equivalent O(1) atoms to form distorted YO7 hexagonal pyramids that share corners with two equivalent Y(1)O7 hexagonal pyramids,  a cornercorner with one Hf(1)O5 trigonal bipyramid, edges with three equivalent Y(1)O7 hexagonal pyramids, edges with four equivalent Y(2)O7 hexagonal pyramids, and edges with two equivalent Hf(1)O5 trigonal bipyramids. Hf(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted HfO5 trigonal bipyramids that share  a cornercorner with one Y(2)O7 hexagonal pyramid, corners with three equivalent Y(1)O7 hexagonal pyramids, corners with two equivalent Hf(1)O5 trigonal bipyramids, edges with two equivalent Y(1)O7 hexagonal pyramids, and edges with two equivalent Y(2)O7 hexagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Y(1) and three equivalent Y(2) atoms to form OY4 tetrahedra that share corners with two equivalent O(4)Y2Hf2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra, corners with five equivalent O(3)Y3Hf tetrahedra, corners with five equivalent O(5)Y3Hf tetrahedra,  an edgeedge with one O(4)Y2Hf2 tetrahedra,  an edgeedge with one O(3)Y3Hf tetrahedra, and edges with two equivalent O(1)Y4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Y(1) and one Hf(1) atom. In the third O site, O(3) is bonded to one Y(1), two equivalent Y(2), and one Hf(1) atom to form OY3Hf tetrahedra that share  a cornercorner with one O(4)Y2Hf2 tetrahedra,  a cornercorner with one O(5)Y3Hf tetrahedra, corners with two equivalent O(3)Y3Hf tetrahedra, corners with five equivalent O(1)Y4 tetrahedra,  an edgeedge with one O(1)Y4 tetrahedra, edges with two equivalent O(4)Y2Hf2 tetrahedra, and edges with two equivalent O(5)Y3Hf tetrahedra. In the fourth O site, O(4) is bonded to one Y(1), one Y(2), and two equivalent Hf(1) atoms to form OY2Hf2 tetrahedra that share  a cornercorner with one O(3)Y3Hf tetrahedra,  a cornercorner with one O(5)Y3Hf tetrahedra, corners with two equivalent O(4)Y2Hf2 tetrahedra, corners with two equivalent O(1)Y4 tetrahedra,  an edgeedge with one O(1)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 one Y(2), two equivalent Y(1), and one Hf(1) atom to form OY3Hf tetrahedra that share  a cornercorner with one O(4)Y2Hf2 tetrahedra,  a cornercorner with one O(3)Y3Hf tetrahedra, corners with two equivalent O(5)Y3Hf tetrahedra, corners with five equivalent O(1)Y4 tetrahedra, edges with two equivalent O(4)Y2Hf2 tetrahedra, and edges with two equivalent O(3)Y3Hf tetrahedra. is represented by the CIF file [CIF]
data_Y2HfO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.744
_cell_length_b   10.755
_cell_length_c   11.630
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   468.332
_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  0.122  0.224  1.0
  Y  Y1  1  0.250  0.130  0.561  1.0
  Y  Y2  1  0.750  0.370  0.061  1.0
  Y  Y3  1  0.750  0.378  0.724  1.0
  Y  Y4  1  0.250  0.622  0.276  1.0
  Y  Y5  1  0.250  0.630  0.939  1.0
  Y  Y6  1  0.750  0.870  0.439  1.0
  Y  Y7  1  0.750  0.878  0.776  1.0
  Hf  Hf8  1  0.250  0.170  0.886  1.0
  Hf  Hf9  1  0.750  0.330  0.386  1.0
  Hf  Hf10  1  0.250  0.670  0.614  1.0
  Hf  Hf11  1  0.750  0.830  0.114  1.0
  O  O12  1  0.750  0.004  0.605  1.0
  O  O13  1  0.250  0.995  0.844  1.0
  O  O14  1  0.250  0.230  0.051  1.0
  O  O15  1  0.750  0.245  0.889  1.0
  O  O16  1  0.750  0.249  0.229  1.0
  O  O17  1  0.250  0.251  0.729  1.0
  O  O18  1  0.250  0.255  0.389  1.0
  O  O19  1  0.750  0.270  0.551  1.0
  O  O20  1  0.750  0.505  0.344  1.0
  O  O21  1  0.250  0.496  0.105  1.0
  O  O22  1  0.750  0.504  0.895  1.0
  O  O23  1  0.250  0.495  0.656  1.0
  O  O24  1  0.250  0.730  0.449  1.0
  O  O25  1  0.750  0.745  0.611  1.0
  O  O26  1  0.750  0.749  0.271  1.0
  O  O27  1  0.250  0.751  0.771  1.0
  O  O28  1  0.250  0.755  0.111  1.0
  O  O29  1  0.750  0.770  0.949  1.0
  O  O30  1  0.750  0.005  0.156  1.0
  O  O31  1  0.250  0.996  0.395  1.0
[/CIF]
.