Materials Data on Na5CrO4 by Materials Project

Abstract

Na5CrO4 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. there are five inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a distorted trigonal planar geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.24–2.87 Å. In the second Na1+ site, Na1+ is bonded in a distorted see-saw-like geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.42–2.48 Å. In the third Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with two equivalent CrO4 tetrahedra, corners with five NaO4 tetrahedra, and an edgeedge with one CrO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.34–2.58 Å. In the fourth Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with two equivalent CrO4 tetrahedra, corners with five NaO4 tetrahedra, and an edgeedge with one CrO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.30–2.44 Å. In the fifth Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.41–2.70 Å. Cr3+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with four NaO4 tetrahedra and edges with two NaO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.91–1.95 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Cr3+ atom. In the second O2- site, O2- is bonded to five Na1+ and one Cr3+ atom to form a mixture of distorted edge and corner-sharing ONa5Cr octahedra. The corner-sharing octahedra tilt angles range from 52–73°. In the third O2- site, O2- is bonded in a 7-coordinate geometry to six Na1+ and one Cr3+ atom. In the fourth O2- site, O2- is bonded to five Na1+ and one Cr3+ atom to form a mixture of edge and corner-sharing ONa5Cr octahedra. The corner-sharing octahedra tilt angles range from 54–69°.