Materials Data on Mg(AlS2)2 by Materials Project

Abstract

MgAl2S4 crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three MgAl2S4 sheets oriented in the (0, 0, 1) direction. Mg2+ is bonded to six equivalent S2- atoms to form MgS6 octahedra that share corners with six equivalent AlS4 tetrahedra and edges with six equivalent MgS6 octahedra. All Mg–S bond lengths are 2.55 Å. Al3+ is bonded to four S2- atoms to form AlS4 tetrahedra that share corners with three equivalent MgS6 octahedra and corners with six equivalent AlS4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are one shorter (2.17 Å) and three longer (2.35 Å) Al–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a trigonal non-coplanar geometry to three equivalent Al3+ atoms. In the second S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Mg2+ and one Al3+ atom.