Materials Data on KCr2FeHO8 by Materials Project
KCr2FeHO8 crystallizes in the monoclinic P2_1/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 2.66–3.20 Å. There are two inequivalent Cr+5.50+ sites. In the first Cr+5.50+ site, Cr+5.50+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with three equivalent FeHO5 octahedra. The corner-sharing octahedra tilt angles range from 33–47°. There are a spread of Cr–O bond distances ranging from 1.62–1.70 Å. In the second Cr+5.50+ site, Cr+5.50+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with two equivalent FeHO5 octahedra. The corner-sharing octahedral tilt angles are 36°. There are a spread of Cr–O bond distances ranging from 1.61–1.73 Å. Fe3+ is bonded to one H1+ and five O2- atoms to form FeHO5 octahedra that share corners with five CrO4 tetrahedra. The Fe–H bond length is 1.66 Å. There are a spread of Fe–O bond distances ranging from 1.93–2.02 Å. H1+ is bonded in a single-bond geometry to one Fe3+ atom. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one Cr+5.50+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Cr+5.50+, and one Fe3+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to two equivalent K1+ and one Cr+5.50+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr+5.50+ and one Fe3+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Cr+5.50+, and one Fe3+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one Cr+5.50+ atom.