Materials Data on KCr(SO4)2 by Materials Project

KCr(SO4)2 crystallizes in the trigonal P-3c1 space group. The structure is three-dimensional. K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share edges with six equivalent KO12 cuboctahedra, edges with six equivalent SO4 tetrahedra, and faces with two equivalent CrO6 octahedra. There are six shorter (2.95 Å) and six longer (3.29 Å) K–O bond lengths. Cr3+ is bonded to six equivalent O2- atoms to form CrO6 octahedra that share corners with six equivalent SO4 tetrahedra and faces with two equivalent KO12 cuboctahedra. All Cr–O bond lengths are 2.01 Å. S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three equivalent CrO6 octahedra and edges with three equivalent KO12 cuboctahedra. The corner-sharing octahedral tilt angles are 42°. There is one shorter (1.46 Å) and three longer (1.50 Å) S–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one S6+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Cr3+, and one S6+ atom.