Materials Data on Hf2P2O9 by Materials Project

Abstract

Hf2P2O9 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. Hf4+ is bonded to seven O2- atoms to form HfO7 pentagonal bipyramids that share a cornercorner with one HfO7 pentagonal bipyramid, corners with four equivalent PO4 tetrahedra, edges with two equivalent HfO7 pentagonal bipyramids, and an edgeedge with one PO4 tetrahedra. There are a spread of Hf–O bond distances ranging from 1.94–2.27 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent HfO7 pentagonal bipyramids and an edgeedge with one HfO7 pentagonal bipyramid. There is two shorter (1.51 Å) and two longer (1.58 Å) P–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Hf4+ and one P5+ atom. In the second O2- site, O2- is bonded in a linear geometry to two equivalent Hf4+ atoms. In the third O2- site, O2- is bonded in a linear geometry to one Hf4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a linear geometry to one Hf4+ and one P5+ atom.