HfP2O7 crystallizes in the cubic Pa-3 space group. Hf(1) is bonded to six equivalent O(2) atoms to form HfO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1) and three equivalent O(2) atoms to form PO4 tetrahedra that share corners with three equivalent Hf(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 10°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a linear geometry to one Hf(1) and one P(1) atom.
HfP2O7 crystallizes in the cubic Pa-3 space group. Hf(1) is bonded to six equivalent O(2) atoms to form HfO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. All Hf(1)-O(2) bond lengths are 2.04 Å. P(1) is bonded to one O(1) and three equivalent O(2) atoms to form PO4 tetrahedra that share corners with three equivalent Hf(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 10°. The P(1)-O(1) bond length is 1.57 Å. All P(1)-O(2) bond lengths are 1.50 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a linear geometry to one Hf(1) and one P(1) atom.