The compound described by HfP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form HfO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. In the second Hf site, Hf(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms to form HfO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with four equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Hf(2)O6 octahedra, corners with two equivalent Hf(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-46°. In the second P site, P(2) is bonded to one O(2), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Hf(1)O6 octahedra, corners with two equivalent Hf(2)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-45°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Hf(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Hf(1) and one P(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Hf(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Hf(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Hf(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Hf(2) and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_HfP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.024
_cell_length_b   7.096
_cell_length_c   8.414
_cell_angle_alpha   91.705
_cell_angle_beta   94.250
_cell_angle_gamma   105.575
_symmetry_Int_Tables_number   1
_cell_volume   287.716
_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
  Hf  Hf0  1  0.000  0.000  0.000  1.0
  Hf  Hf1  1  0.500  0.500  0.500  1.0
  P  P2  1  0.499  0.134  0.760  1.0
  P  P3  1  0.126  0.752  0.689  1.0
  P  P4  1  0.874  0.248  0.311  1.0
  P  P5  1  0.501  0.866  0.240  1.0
  O  O6  1  0.331  0.171  0.895  1.0
  O  O7  1  0.053  0.773  0.859  1.0
  O  O8  1  0.741  0.061  0.821  1.0
  O  O9  1  0.312  0.618  0.672  1.0
  O  O10  1  0.585  0.307  0.658  1.0
  O  O11  1  0.298  0.965  0.643  1.0
  O  O12  1  0.873  0.696  0.571  1.0
  O  O13  1  0.127  0.304  0.429  1.0
  O  O14  1  0.702  0.035  0.357  1.0
  O  O15  1  0.415  0.693  0.342  1.0
  O  O16  1  0.688  0.382  0.328  1.0
  O  O17  1  0.259  0.939  0.179  1.0
  O  O18  1  0.947  0.227  0.141  1.0
  O  O19  1  0.669  0.829  0.105  1.0
[/CIF]
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The compound described by HfP2O7 crystallizes in the triclinic P-1 space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form HfO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. In the second Hf site, Hf(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms to form HfO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with four equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Hf(2)O6 octahedra, corners with two equivalent Hf(1)O6 octahedra, and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 28-46°. In the second P site, P(2) is bonded to one O(2), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Hf(1)O6 octahedra, corners with two equivalent Hf(2)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-45°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Hf(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Hf(1) and one P(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Hf(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Hf(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Hf(2) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Hf(2) and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_HfP2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.024
_cell_length_b   7.096
_cell_length_c   8.414
_cell_angle_alpha   91.705
_cell_angle_beta   94.250
_cell_angle_gamma   105.575
_symmetry_Int_Tables_number   1
_cell_volume   287.716
_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
  Hf  Hf0  1  0.000  0.000  0.000  1.0
  Hf  Hf1  1  0.500  0.500  0.500  1.0
  P  P2  1  0.499  0.134  0.760  1.0
  P  P3  1  0.126  0.752  0.689  1.0
  P  P4  1  0.874  0.248  0.311  1.0
  P  P5  1  0.501  0.866  0.240  1.0
  O  O6  1  0.331  0.171  0.895  1.0
  O  O7  1  0.053  0.773  0.859  1.0
  O  O8  1  0.741  0.061  0.821  1.0
  O  O9  1  0.312  0.618  0.672  1.0
  O  O10  1  0.585  0.307  0.658  1.0
  O  O11  1  0.298  0.965  0.643  1.0
  O  O12  1  0.873  0.696  0.571  1.0
  O  O13  1  0.127  0.304  0.429  1.0
  O  O14  1  0.702  0.035  0.357  1.0
  O  O15  1  0.415  0.693  0.342  1.0
  O  O16  1  0.688  0.382  0.328  1.0
  O  O17  1  0.259  0.939  0.179  1.0
  O  O18  1  0.947  0.227  0.141  1.0
  O  O19  1  0.669  0.829  0.105  1.0
[/CIF]
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