Materials Data on HfP2O7 by Materials Project
HfP2O7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Hf4+ sites. In the first Hf4+ site, Hf4+ is bonded to six O2- atoms to form HfO6 octahedra that share corners with six PO4 tetrahedra. There are four shorter (2.07 Å) and two longer (2.08 Å) Hf–O bond lengths. In the second Hf4+ site, Hf4+ is bonded to six O2- atoms to form HfO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Hf–O bond distances ranging from 2.06–2.08 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three HfO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 28–46°. There are a spread of P–O bond distances ranging from 1.52–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three HfO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 36–48°. There are a spread of P–O bond distances ranging from 1.52–1.62 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Hf4+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Hf4+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Hf4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Hf4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Hf4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Hf4+ and one P5+ atom.