Materials Data on KCr2Fe(HO4)2 by Materials Project
KCr2Fe(HO4)2 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 2.70–3.18 Å. Cr5+ is bonded to four O2- atoms to form CrO4 tetrahedra that share corners with two equivalent FeH2O4 octahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of Cr–O bond distances ranging from 1.61–1.73 Å. Fe3+ is bonded to two equivalent H1+ and four equivalent O2- atoms to form FeH2O4 octahedra that share corners with four equivalent CrO4 tetrahedra. Both Fe–H bond lengths are 1.75 Å. All Fe–O bond lengths are 1.93 Å. H1+ is bonded in a single-bond geometry to one Fe3+ atom. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Cr5+, and one Fe3+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to two equivalent K1+ and one Cr5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one K1+ and one Cr5+ atom.