Materials Data on CaPHO4 by Materials Project

Abstract

CaHPO4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.55 Å. In the second Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.31–2.56 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.53–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.52–1.67 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 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.75 Å) H–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ca2+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one P5+, and one H1+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ca2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a water-like geometry to two Ca2+ and two H1+ atoms. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to two Ca2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one P5+ atom.