Materials Data on Na2Ca(PO4)2 by Materials Project

Abstract

Na2Ca(PO4)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 5-coordinate geometry to six O atoms. There are a spread of Na–O bond distances ranging from 2.28–2.91 Å. In the second Na site, Na is bonded to five O atoms to form NaO5 trigonal bipyramids that share corners with two equivalent CaO7 pentagonal bipyramids, corners with five PO4 tetrahedra, and an edgeedge with one CaO7 pentagonal bipyramid. There are a spread of Na–O bond distances ranging from 2.37–2.46 Å. Ca is bonded to seven O atoms to form distorted CaO7 pentagonal bipyramids that share corners with five PO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, an edgeedge with one PO4 tetrahedra, and an edgeedge with one NaO5 trigonal bipyramid. There are a spread of Ca–O bond distances ranging from 2.34–2.64 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 three equivalent CaO7 pentagonal bipyramids and corners with four equivalent NaO5 trigonal 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 corners with two equivalent CaO7 pentagonal bipyramids, a cornercorner with one NaO5 trigonal bipyramid, and an edgeedge with one CaO7 pentagonal bipyramid. There are a spread of P–O bond distances ranging from 1.54–1.56 Å. There are eight inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to one Ca and one P atom. In the second O site, O is bonded in a distorted tetrahedral geometry to two Na, one Ca, and one P atom. In the third O site, O is bonded in a 3-coordinate geometry to two Na and one P atom. In the fourth O site, O is bonded in a 1-coordinate geometry to one Na, one Ca, and one P atom. In the fifth O site, O is bonded in a 4-coordinate geometry to two Na, one Ca, and one P atom. In the sixth O site, O is bonded in a 4-coordinate geometry to two Na, one Ca, and one P atom. In the seventh O site, O is bonded in a distorted trigonal non-coplanar geometry to one Na, one Ca, and one P atom. In the eighth O site, O is bonded in a distorted single-bond geometry to one Na, one Ca, and one P atom.