Materials Data on Hf(PO5)2 by Materials Project
Hf(PO4)2O2 crystallizes in the monoclinic P2_1 space group. The structure is two-dimensional and consists of two water water molecules and one Hf(PO4)2 sheet oriented in the (0, 0, 1) direction. In the Hf(PO4)2 sheet, Hf is bonded to six O atoms to form HfO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Hf–O bond distances ranging from 2.01–2.11 Å. There are two inequivalent P sites. In the first P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with four equivalent HfO6 octahedra. The corner-sharing octahedra tilt angles range from 4–35°. All P–O bond lengths are 1.54 Å. In the second P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with two equivalent HfO6 octahedra. The corner-sharing octahedra tilt angles range from 13–29°. There is two shorter (1.52 Å) and two longer (1.57 Å) P–O bond length. There are eight inequivalent O sites. In the first O site, O is bonded in a linear geometry to one Hf and one P atom. In the second O site, O is bonded in a bent 150 degrees geometry to one Hf and one P atom. In the third O site, O is bonded in a bent 150 degrees geometry to one Hf and one P atom. In the fourth O site, O is bonded in a bent 150 degrees geometry to one Hf and one P atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to one Hf and one P atom. In the sixth O site, O is bonded in a linear geometry to one Hf and one P atom. In the seventh O site, O is bonded in a single-bond geometry to one P atom. In the eighth O site, O is bonded in a single-bond geometry to one P atom.