DOE OSTI2020
CrO2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are twelve inequivalent Cr4+ sites. In the first Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with three CrO4 tetrahedra and edges with four CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.84–2.10 Å. In the second Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with three equivalent CrO4 tetrahedra and edges with four CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.81–2.10 Å. In the third Cr4+ site, Cr4+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are a spread of Cr–O bond distances ranging from 1.70–1.80 Å. In the fourth Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four CrO4 tetrahedra and edges with three CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.87–2.05 Å. In the fifth Cr4+ site, Cr4+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–59°. There are a spread of Cr–O bond distances ranging from 1.82–1.87 Å. In the sixth Cr4+ site, Cr4+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–55°. There is two shorter (1.68 Å) and two longer (1.78 Å) Cr–O bond length. In the seventh Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six CrO4 tetrahedra and edges with two equivalent CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 2.01–2.05 Å. In the eighth Cr4+ site, Cr4+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–54°. There are a spread of Cr–O bond distances ranging from 1.65–1.78 Å. In the ninth Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with five CrO4 tetrahedra and edges with three CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.85–2.09 Å. In the tenth Cr4+ site, Cr4+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Cr–O bond distances ranging from 1.70–1.82 Å. In the eleventh Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with three equivalent CrO4 tetrahedra and edges with four CrO6 octahedra. There are a spread of Cr–O bond distances ranging from 1.83–2.09 Å. In the twelfth Cr4+ site, Cr4+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Cr–O bond distances ranging from 1.79–1.91 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to two Cr4+ atoms. In the second O2- site, O2- is bonded in a water-like geometry to two equivalent Cr4+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to three Cr4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to four Cr4+ atoms. In the fifth O2- site, O2- is bonded in a water-like geometry to two Cr4+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the ninth O2- site, O2- is bonded in a distorted T-shaped geometry to three Cr4+ atoms. In the tenth O2- site, O2- is bonded in a bent 120 degrees geometry to two Cr4+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr4+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the seventeenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr4+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Cr4+ atoms. In the nineteenth O2- site, O2- is bonded in a water-like geometry to two equivalent Cr4+ atoms. In the twentieth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the twenty-first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the twenty-second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Cr4+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms. In the twenty-fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr4+ atoms.