Materials Data on Sr11(MgSi5)2 by Materials Project
Sr11(MgSi5)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are six inequivalent Sr sites. In the first Sr site, Sr is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Sr–Si bond distances ranging from 3.24–3.34 Å. In the second Sr site, Sr is bonded in a 5-coordinate geometry to five Si atoms. There are a spread of Sr–Si bond distances ranging from 3.36–3.53 Å. In the third Sr site, Sr is bonded in a 5-coordinate geometry to seven Si atoms. There are a spread of Sr–Si bond distances ranging from 3.18–3.31 Å. In the fourth Sr site, Sr is bonded in a 7-coordinate geometry to seven Si atoms. There are a spread of Sr–Si bond distances ranging from 3.24–3.43 Å. In the fifth Sr site, Sr is bonded in a 6-coordinate geometry to three equivalent Mg and six Si atoms. There are one shorter (3.44 Å) and two longer (3.50 Å) Sr–Mg bond lengths. There are a spread of Sr–Si bond distances ranging from 3.24–3.45 Å. In the sixth Sr site, Sr is bonded in a square co-planar geometry to four Si atoms. There are two shorter (3.35 Å) and two longer (3.38 Å) Sr–Si bond lengths. Mg is bonded to three equivalent Sr and four Si atoms to form a mixture of distorted edge and face-sharing MgSr3Si4 tetrahedra. There are a spread of Mg–Si bond distances ranging from 2.81–2.94 Å. There are five inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to seven Sr and two Si atoms. There are one shorter (2.46 Å) and one longer (2.47 Å) Si–Si bond lengths. In the second Si site, Si is bonded in a 9-coordinate geometry to eight Sr and one Si atom. The Si–Si bond length is 2.46 Å. In the third Si site, Si is bonded in a 9-coordinate geometry to six Sr, one Mg, and two Si atoms. In the fourth Si site, Si is bonded in a 9-coordinate geometry to seven Sr and two Si atoms. The Si–Si bond length is 2.47 Å. In the fifth Si site, Si is bonded in a 9-coordinate geometry to six Sr and three equivalent Mg atoms.