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DOE OSTI2020

Materials Data on K3CrO8 by Materials Project

K3CrO8 crystallizes in the tetragonal I-42m space group. The structure is three-dimensional. there are two inequivalent K sites. In the first K site, K is bonded in a 4-coordinate geometry to twelve O atoms. There are a spread of K–O bond distances ranging from 2.71–3.21 Å. In the second K site, K is bonded to eight O atoms to form KO8 hexagonal bipyramids that share corners with four equivalent CrO8 hexagonal bipyramids, corners with four equivalent OK3CrO trigonal bipyramids, and edges with two equivalent CrO8 hexagonal bipyramids. There are four shorter (2.83 Å) and four longer (2.84 Å) K–O bond lengths. Cr is bonded to eight O atoms to form distorted CrO8 hexagonal bipyramids that share corners with four equivalent KO8 hexagonal bipyramids, corners with four equivalent OK3CrO trigonal bipyramids, and edges with two equivalent KO8 hexagonal bipyramids. There is four shorter (1.91 Å) and four longer (1.99 Å) Cr–O bond length. There are two inequivalent O sites. In the first O site, O is bonded in a 1-coordinate geometry to five K, one Cr, and one O atom. The O–O bond length is 1.45 Å. In the second O site, O is bonded to three K, one Cr, and one O atom to form distorted OK3CrO trigonal bipyramids that share a cornercorner with one KO8 hexagonal bipyramid, a cornercorner with one CrO8 hexagonal bipyramid, corners with ten equivalent OK3CrO trigonal bipyramids, and an edgeedge with one OK3CrO trigonal bipyramid.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KCr4O8 by Materials Project

KCr4O8 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. K1+ is bonded in a distorted body-centered cubic geometry to eight equivalent O2- atoms. All K–O bond lengths are 2.95 Å. Cr+3.75+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Cr–O bond distances ranging from 1.90–2.00 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three equivalent Cr+3.75+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent K1+ and three equivalent Cr+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2CrO4 by Materials Project

K2CrO4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 1-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.69–3.31 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.78–3.31 Å. Cr6+ is bonded in a tetrahedral geometry to four O2- atoms. There is one shorter (1.66 Å) and three longer (1.67 Å) Cr–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to five K1+ and one Cr6+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to five K1+ and one Cr6+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to four K1+ and one Cr6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KCr3O8 by Materials Project

KCr3O8 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. K1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.86–3.30 Å. There are two inequivalent Cr5+ sites. In the first Cr5+ site, Cr5+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedra tilt angles range from 28–42°. There are a spread of Cr–O bond distances ranging from 1.62–1.69 Å. In the second Cr5+ site, Cr5+ is bonded to six O2- atoms to form corner-sharing CrO6 octahedra. There is two shorter (1.99 Å) and four longer (2.00 Å) Cr–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one K1+ and two Cr5+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two Cr5+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one Cr5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3CrO4 by Materials Project

K3CrO4 crystallizes in the tetragonal I-42m space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to four equivalent O2- atoms to form distorted KO4 tetrahedra that share corners with four equivalent KO4 tetrahedra, corners with four equivalent CrO4 tetrahedra, and corners with four equivalent KO4 trigonal pyramids. All K–O bond lengths are 2.59 Å. In the second K1+ site, K1+ is bonded to four equivalent O2- atoms to form distorted KO4 trigonal pyramids that share corners with four equivalent CrO4 tetrahedra and corners with eight equivalent KO4 tetrahedra. All K–O bond lengths are 3.02 Å. Cr5+ is bonded to four equivalent O2- atoms to form CrO4 tetrahedra that share corners with eight equivalent KO4 tetrahedra and corners with four equivalent KO4 trigonal pyramids. All Cr–O bond lengths are 1.74 Å. O2- is bonded in a 1-coordinate geometry to three K1+ and one Cr5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2Cr2O7 by Materials Project

K2Cr2O7 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two K2Cr2O7 sheets oriented in the (1, 0, 0) direction. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of K–O bond distances ranging from 2.63–2.95 Å. In the second K1+ site, K1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of K–O bond distances ranging from 2.59–2.72 Å. There are two inequivalent Cr6+ sites. In the first Cr6+ site, Cr6+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.63–1.77 Å. In the second Cr6+ site, Cr6+ is bonded to four O2- atoms to form corner-sharing CrO4 tetrahedra. There are a spread of Cr–O bond distances ranging from 1.68–1.90 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one Cr6+ atom. In the second O2- site, O2- is bonded in a linear geometry to two Cr6+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one Cr6+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two K1+ and one Cr6+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two K1+ and one Cr6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KCr20O40 by Materials Project

KCr20O40 is zeta iron carbide-derived structured and crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. K1+ is bonded in a distorted body-centered cubic geometry to eight equivalent O2- atoms. All K–O bond lengths are 2.97 Å. There are three inequivalent Cr+3.95+ sites. In the first Cr+3.95+ site, Cr+3.95+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Cr–O bond distances ranging from 1.90–1.99 Å. In the second Cr+3.95+ site, Cr+3.95+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Cr–O bond distances ranging from 1.89–1.97 Å. In the third Cr+3.95+ site, Cr+3.95+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Cr–O bond distances ranging from 1.90–1.98 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Cr+3.95+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr+3.95+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr+3.95+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Cr+3.95+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one K1+ and three Cr+3.95+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Cr+3.95+ atoms.

36 MATERIALS SCIENCE↗