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.