Materials Data on Na4CrO4 by Materials Project

Abstract

Na4CrO4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five O2- atoms to form NaO5 square pyramids that share corners with three equivalent NaO5 square pyramids, a cornercorner with one CrO4 tetrahedra, corners with two equivalent NaO4 tetrahedra, edges with five NaO5 square pyramids, and edges with two equivalent CrO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.39–2.51 Å. In the second Na1+ site, Na1+ is bonded to five O2- atoms to form NaO5 square pyramids that share corners with three equivalent NaO5 square pyramids, corners with two equivalent NaO4 tetrahedra, corners with three equivalent CrO4 tetrahedra, edges with five NaO5 square pyramids, and an edgeedge with one CrO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.40–2.49 Å. In the third Na1+ site, Na1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.34–2.38 Å. In the fourth Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with four NaO5 square pyramids, corners with four equivalent CrO4 tetrahedra, and edges with two equivalent NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.31–2.36 Å. Cr4+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with four NaO5 square pyramids, corners with four equivalent NaO4 tetrahedra, and edges with three NaO5 square pyramids. There are a spread of Cr–O bond distances ranging from 1.79–1.83 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one Cr4+ atom. In the second O2- site, O2- is bonded to five Na1+ and one Cr4+ atom to form a mixture of distorted corner and edge-sharing ONa5Cr octahedra. The corner-sharing octahedra tilt angles range from 12–26°. In the third O2- site, O2- is bonded to five Na1+ and one Cr4+ atom to form a mixture of distorted corner and edge-sharing ONa5Cr octahedra. The corner-sharing octahedra tilt angles range from 12–15°. In the fourth O2- site, O2- is bonded to five Na1+ and one Cr4+ atom to form a mixture of distorted corner and edge-sharing ONa5Cr octahedra. The corner-sharing octahedra tilt angles range from 12–26°.