Materials Data on K2Ca2(SO4)3 by Materials Project

Abstract

K2Ca2(SO4)3 crystallizes in the cubic P2_13 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.90–3.30 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.85 Å) and three longer (3.05 Å) K–O bond lengths. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six equivalent SO4 tetrahedra. There are three shorter (2.31 Å) and three longer (2.38 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six equivalent SO4 tetrahedra. There are three shorter (2.32 Å) and three longer (2.39 Å) Ca–O bond lengths. S6+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with four CaO6 octahedra. The corner-sharing octahedra tilt angles range from 20–52°. All S–O bond lengths are 1.49 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ca2+, and one S6+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Ca2+, and one S6+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one Ca2+, and one S6+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, one Ca2+, and one S6+ atom.