Materials Data on KAl(SO4)2 by Materials Project
KAl(SO4)2 crystallizes in the trigonal P321 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 AlO6 octahedra. There are six shorter (2.99 Å) and six longer (3.27 Å) K–O bond lengths. Al3+ is bonded to six equivalent O2- atoms to form AlO6 octahedra that share corners with six equivalent SO4 tetrahedra and faces with two equivalent KO12 cuboctahedra. All Al–O bond lengths are 1.90 Å. S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with three equivalent AlO6 octahedra and edges with three equivalent KO12 cuboctahedra. The corner-sharing octahedral tilt angles are 27°. There is one shorter (1.46 Å) and three longer (1.49 Å) S–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one K1+, one Al3+, and one S6+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one S6+ atom.