Materials Data on CaPO6 by Materials Project
CaPO4O2 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of four oxygen molecules and two CaPO4 sheets oriented in the (0, 1, 0) direction. In each CaPO4 sheet, 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 edges with two equivalent PO4 tetrahedra. There are two shorter (2.30 Å) and four longer (2.46 Å) Ca–O bond lengths. P is bonded to four O atoms to form PO4 tetrahedra that share corners with two equivalent CaO6 pentagonal pyramids and edges with two equivalent CaO6 pentagonal pyramids. There is two shorter (1.54 Å) and two longer (1.56 Å) P–O bond length. There are two inequivalent O sites. In the first O site, O is bonded in a distorted L-shaped geometry to one Ca and one P atom. In the second O site, O is bonded in a 3-coordinate geometry to two equivalent Ca and one P atom.