DOI: 10.17188/1306845
title: Materials Data on NaCr6O11 by Materials Project

description: NaCr6O11 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Na1+ is bonded to twelve O2- atoms to form NaO12 cuboctahedra that share corners with six equivalent NaO12 cuboctahedra, edges with six CrO6 octahedra, edges with three equivalent CrO5 trigonal bipyramids, and faces with six CrO6 octahedra. There are a spread of Na–O bond distances ranging from 2.70–2.92 Å. There are six inequivalent Cr+3.50+ sites. In the first Cr+3.50+ site, Cr+3.50+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four CrO6 octahedra, corners with two equivalent CrO5 trigonal bipyramids, edges with two equivalent NaO12 cuboctahedra, and edges with four CrO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Cr–O bond distances ranging from 1.92–2.03 Å. In the second Cr+3.50+ site, Cr+3.50+ is bonded to five O2- atoms to form CrO5 trigonal bipyramids that share corners with twelve CrO6 octahedra and edges with three equivalent NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 41–56°. There are a spread of Cr–O bond distances ranging from 1.82–2.12 Å. In the third Cr+3.50+ site, Cr+3.50+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six CrO6 octahedra, corners with three equivalent CrO5 trigonal bipyramids, faces with three equivalent NaO12 cuboctahedra, and a faceface with one CrO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Cr–O bond distances ranging from 1.96–2.06 Å. In the fourth Cr+3.50+ site, Cr+3.50+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six CrO6 octahedra, corners with three equivalent CrO5 trigonal bipyramids, faces with three equivalent NaO12 cuboctahedra, and a faceface with one CrO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Cr–O bond distances ranging from 1.96–2.06 Å. In the fifth Cr+3.50+ site, Cr+3.50+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four CrO6 octahedra, corners with two equivalent CrO5 trigonal bipyramids, edges with two equivalent NaO12 cuboctahedra, and edges with four CrO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Cr–O bond distances ranging from 1.92–2.03 Å. In the sixth Cr+3.50+ site, Cr+3.50+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four CrO6 octahedra, corners with two equivalent CrO5 trigonal bipyramids, edges with two equivalent NaO12 cuboctahedra, and edges with four CrO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Cr–O bond distances ranging from 1.93–2.03 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Cr+3.50+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Na1+ and three Cr+3.50+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+ and three Cr+3.50+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and three Cr+3.50+ atoms. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Na1+ and three Cr+3.50+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and three Cr+3.50+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and three Cr+3.50+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Na1+ and three Cr+3.50+ atoms. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and three Cr+3.50+ atoms. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and three Cr+3.50+ atoms. In the eleventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Cr+3.50+ atoms.