DOE OSTI2020
Yb2Fe4Si9 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Yb2+ is bonded in a 6-coordinate geometry to eight Si+1.33- atoms. There are a spread of Yb–Si bond distances ranging from 2.95–3.33 Å. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded in a 10-coordinate geometry to ten Si+1.33- atoms. There are a spread of Fe–Si bond distances ranging from 2.27–2.63 Å. In the second Fe2+ site, Fe2+ is bonded to seven Si+1.33- atoms to form distorted edge-sharing FeSi7 hexagonal pyramids. There are a spread of Fe–Si bond distances ranging from 2.31–2.45 Å. There are five inequivalent Si+1.33- sites. In the first Si+1.33- site, Si+1.33- is bonded in a 10-coordinate geometry to three equivalent Yb2+, three equivalent Fe2+, and four Si+1.33- atoms. There are a spread of Si–Si bond distances ranging from 2.44–2.59 Å. In the second Si+1.33- site, Si+1.33- is bonded in a 6-coordinate geometry to three equivalent Yb2+, three equivalent Fe2+, and three equivalent Si+1.33- atoms. All Si–Si bond lengths are 2.64 Å. In the third Si+1.33- site, Si+1.33- is bonded in a 4-coordinate geometry to one Yb2+, four equivalent Fe2+, and six Si+1.33- atoms. There are one shorter (2.55 Å) and two longer (2.57 Å) Si–Si bond lengths. In the fourth Si+1.33- site, Si+1.33- is bonded in a 4-coordinate geometry to one Yb2+, four equivalent Fe2+, and three equivalent Si+1.33- atoms. In the fifth Si+1.33- site, Si+1.33- is bonded in a 8-coordinate geometry to six equivalent Fe2+ and eight Si+1.33- atoms.