Materials Data on CaPO4 by Materials Project
CaPO4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded to seven O atoms to form distorted CaO7 pentagonal bipyramids that share corners with five PO4 tetrahedra, an edgeedge with one CaO7 pentagonal bipyramid, and an edgeedge with one PO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.31–2.64 Å. In the second Ca site, Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.38–2.67 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 CaO7 pentagonal bipyramids. There are a spread of P–O bond distances ranging from 1.54–1.56 Å. In the second P site, P is bonded to four O atoms to form PO4 tetrahedra that share a cornercorner with one CaO7 pentagonal bipyramid and an edgeedge with one CaO7 pentagonal bipyramid. There is three shorter (1.54 Å) and one longer (1.56 Å) P–O bond length. There are eight inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Ca and one P atom. In the second O site, O is bonded in a 1-coordinate geometry to three Ca and one P atom. In the third O site, O is bonded in a distorted trigonal planar geometry to two equivalent Ca and one P atom. In the fourth O site, O is bonded in a 1-coordinate geometry to two Ca and one P atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to one Ca and one P atom. In the sixth O site, O is bonded in a 1-coordinate geometry to two Ca and one P atom. In the seventh O site, O is bonded in a 1-coordinate geometry to two Ca and one P atom. In the eighth O site, O is bonded in a distorted trigonal planar geometry to two Ca and one P atom.