Materials Data on HfP2H4O9 by Materials Project

Abstract

HfP2(HO4)2H2O crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of four water molecules and two HfP2(HO4)2 sheets oriented in the (0, 0, 1) direction. In each HfP2(HO4)2 sheet, 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 2.04–2.09 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 equivalent HfO6 octahedra. The corner-sharing octahedra tilt angles range from 20–34°. There is three shorter (1.54 Å) and one longer (1.57 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent HfO6 octahedra. The corner-sharing octahedra tilt angles range from 20–36°. There is three shorter (1.53 Å) and one longer (1.60 Å) P–O bond length. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Hf4+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Hf4+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H1+ 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 distorted bent 150 degrees geometry to one Hf4+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Hf4+ and one P5+ atom.