Materials Data on Mn6Si7 by Materials Project
Mn6Si7 is Frank-Kasper $\mu$ Phase structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded in a 6-coordinate geometry to six equivalent Si+1.71- atoms. There are three shorter (2.41 Å) and three longer (2.44 Å) Mn–Si bond lengths. In the second Mn2+ site, Mn2+ is bonded in a 6-coordinate geometry to twelve Si+1.71- atoms. There are a spread of Mn–Si bond distances ranging from 2.51–3.07 Å. In the third Mn2+ site, Mn2+ is bonded in a 7-coordinate geometry to one Mn2+ and six equivalent Si+1.71- atoms. The Mn–Mn bond length is 2.34 Å. All Mn–Si bond lengths are 2.56 Å. There are two inequivalent Si+1.71- sites. In the first Si+1.71- site, Si+1.71- is bonded to six equivalent Mn2+ and six equivalent Si+1.71- atoms to form edge-sharing SiMn6Si6 cuboctahedra. All Si–Si bond lengths are 2.44 Å. In the second Si+1.71- site, Si+1.71- is bonded in a 12-coordinate geometry to seven Mn2+ and five Si+1.71- atoms. There are two shorter (2.39 Å) and two longer (2.46 Å) Si–Si bond lengths.