Materials Data on SrMg6Si by Materials Project
SrMg6Si crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Sr is bonded to ten Mg and two equivalent Si atoms to form a mixture of distorted face and corner-sharing SrMg10Si2 cuboctahedra. There are a spread of Sr–Mg bond distances ranging from 3.26–3.49 Å. Both Sr–Si bond lengths are 3.25 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a 1-coordinate geometry to two equivalent Sr, four Mg, and one Si atom. There are a spread of Mg–Mg bond distances ranging from 3.11–3.43 Å. The Mg–Si bond length is 2.90 Å. In the second Mg site, Mg is bonded in a 10-coordinate geometry to ten Mg atoms. There are two shorter (3.16 Å) and four longer (3.24 Å) Mg–Mg bond lengths. In the third Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Sr, four Mg, and two equivalent Si atoms. There are one shorter (3.26 Å) and one longer (3.49 Å) Mg–Mg bond lengths. Both Mg–Si bond lengths are 3.04 Å. In the fourth Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Sr and ten Mg atoms. Si is bonded in a 8-coordinate geometry to two equivalent Sr and six Mg atoms.