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.
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