Materials Data on CaP2H2O7 by Materials Project
CaH2P2O7 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six equivalent PO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.26–2.48 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent CaO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 8–52°. There are a spread of P–O bond distances ranging from 1.50–1.63 Å. H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.57 Å) H–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent P5+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one P5+, and one H1+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one P5+, and one H1+ atom. In the fourth O2- site, O2- is bonded in a linear geometry to one Ca2+ and one P5+ atom.