Materials Data on SrMgSi2 by Materials Project
MgSi2Sr crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Sr sites. In the first Sr site, Sr is bonded in a 5-coordinate geometry to four Mg and ten Si atoms. There are a spread of Sr–Mg bond distances ranging from 3.40–3.63 Å. There are a spread of Sr–Si bond distances ranging from 3.23–3.43 Å. In the second Sr site, Sr is bonded in a 7-coordinate geometry to five Mg and nine Si atoms. There are a spread of Sr–Mg bond distances ranging from 3.63–3.74 Å. There are a spread of Sr–Si bond distances ranging from 3.11–3.57 Å. There are two inequivalent Mg sites. In the first Mg site, Mg is bonded to four Sr and four Si atoms to form a mixture of edge and face-sharing MgSr4Si4 tetrahedra. There are a spread of Mg–Si bond distances ranging from 2.72–2.77 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to five Sr and five Si atoms. There are a spread of Mg–Si bond distances ranging from 2.74–2.81 Å. There are four inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to four Sr, four Mg, and one Si atom. The Si–Si bond length is 2.42 Å. In the second Si site, Si is bonded in a 7-coordinate geometry to six Sr and three Si atoms. There are one shorter (2.36 Å) and two longer (2.50 Å) Si–Si bond lengths. In the third Si site, Si is bonded in a 9-coordinate geometry to five Sr, two equivalent Mg, and two Si atoms. The Si–Si bond length is 2.46 Å. In the fourth Si site, Si is bonded in a 9-coordinate geometry to four Sr, three Mg, and two Si atoms.