Materials Data on CsMg6Si by Materials Project

CsMg6Si crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cs is bonded in a 12-coordinate geometry to eight Mg and two equivalent Si atoms. There are a spread of Cs–Mg bond distances ranging from 3.66–3.84 Å. Both Cs–Si bond lengths are 3.72 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a distorted single-bond geometry to two equivalent Cs, five Mg, and one Si atom. There are a spread of Mg–Mg bond distances ranging from 2.94–3.23 Å. The Mg–Si bond length is 2.78 Å. In the second Mg site, Mg is bonded to six Mg atoms to form distorted face-sharing MgMg6 pentagonal pyramids. There are four shorter (3.17 Å) and two longer (3.35 Å) Mg–Mg bond lengths. In the third Mg site, Mg is bonded in a distorted water-like geometry to one Cs, four Mg, and two equivalent Si atoms. Both Mg–Si bond lengths are 2.70 Å. In the fourth Mg site, Mg is bonded to two equivalent Cs and six Mg atoms to form a mixture of distorted corner and face-sharing MgCs2Mg6 hexagonal bipyramids. Si is bonded in a 8-coordinate geometry to two equivalent Cs and six Mg atoms.