Materials Data on Na3Cr2(PO4)3 by Materials Project

Abstract

Na3Cr2(PO4)3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are two shorter (2.49 Å) and four longer (2.50 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.37–2.84 Å. Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.95–2.07 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent CrO6 octahedra. The corner-sharing octahedra tilt angles range from 29–36°. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent CrO6 octahedra. The corner-sharing octahedra tilt angles range from 31–36°. All P–O bond lengths are 1.55 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to three Na1+, one Cr3+, and one P5+ atom to form distorted corner-sharing ONa3CrP trigonal bipyramids. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+, one Cr3+, and one P5+ atom. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Na1+, one Cr3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+, one Cr3+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Cr3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+, one Cr3+, and one P5+ atom.