DOE OSTI2020
Zr(HPO4)2(H2O)2 crystallizes in the monoclinic P2_1 space group. The structure is two-dimensional and consists of four water molecules and one Zr(HPO4)2 sheet oriented in the (0, 0, 1) direction. In the Zr(HPO4)2 sheet, Zr4+ is bonded to six O2- atoms to form ZrO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Zr–O bond distances ranging from 2.05–2.18 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 four equivalent ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 6–39°. There is two shorter (1.54 Å) and two longer (1.55 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 two equivalent ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 16–41°. There are a spread of P–O bond distances ranging from 1.52–1.58 Å. 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 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to one P5+ and one H1+ atom. In the second O2- site, O2- is bonded in a linear geometry to one Zr4+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Zr4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Zr4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one Zr4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Zr4+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted linear geometry to one Zr4+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H1+ atom.