Materials Data on CaPIO8 by Materials Project
CaPO8I crystallizes in the monoclinic P2/c space group. The structure is two-dimensional and consists of one CaPO8I sheet oriented in the (0, 1, 0) direction. Ca is bonded to six O atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent PO4 tetrahedra, edges with two equivalent CaO6 pentagonal pyramids, and an edgeedge with one PO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.31–2.53 Å. P is bonded to four O atoms to form PO4 tetrahedra that share corners with two equivalent CaO6 pentagonal pyramids and an edgeedge with one CaO6 pentagonal pyramid. There is two shorter (1.51 Å) and two longer (1.63 Å) P–O bond length. There are four inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one P and one O atom. The O–O bond length is 1.49 Å. In the second O site, O is bonded in a 1-coordinate geometry to two equivalent Ca and one P atom. In the third O site, O is bonded in a bent 150 degrees geometry to one Ca and one I atom. The O–I bond length is 1.80 Å. In the fourth O site, O is bonded in a water-like geometry to one O and one I atom. The O–I bond length is 2.16 Å. I is bonded in a see-saw-like geometry to four O atoms.