DOE OSTI2020
Yb5(Co2Si7)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Yb2+ sites. In the first Yb2+ site, Yb2+ is bonded to twelve Si+1.14- atoms to form YbSi12 cuboctahedra that share corners with four equivalent YbSi12 cuboctahedra, corners with four equivalent CoSi7 hexagonal pyramids, and faces with four equivalent CoSi7 hexagonal pyramids. There are a spread of Yb–Si bond distances ranging from 2.90–3.03 Å. In the second Yb2+ site, Yb2+ is bonded in a 10-coordinate geometry to ten Si+1.14- atoms. There are a spread of Yb–Si bond distances ranging from 2.92–3.29 Å. In the third Yb2+ site, Yb2+ is bonded in a 10-coordinate geometry to ten Si+1.14- atoms. There are a spread of Yb–Si bond distances ranging from 2.92–3.25 Å. There are two inequivalent Co+1.50+ sites. In the first Co+1.50+ site, Co+1.50+ is bonded to seven Si+1.14- atoms to form distorted CoSi7 hexagonal pyramids that share corners with two equivalent YbSi12 cuboctahedra, corners with four equivalent CoSi7 hexagonal pyramids, an edgeedge with one CoSi7 hexagonal pyramid, and faces with two equivalent YbSi12 cuboctahedra. There are a spread of Co–Si bond distances ranging from 2.28–2.49 Å. In the second Co+1.50+ site, Co+1.50+ is bonded in a 5-coordinate geometry to five Si+1.14- atoms. There are a spread of Co–Si bond distances ranging from 2.31–2.39 Å. There are seven inequivalent Si+1.14- sites. In the first Si+1.14- site, Si+1.14- is bonded in a 8-coordinate geometry to three Yb2+, two Co+1.50+, and three Si+1.14- atoms. There are a spread of Si–Si bond distances ranging from 2.41–2.58 Å. In the second Si+1.14- site, Si+1.14- is bonded in a 9-coordinate geometry to six Yb2+, one Co+1.50+, and two Si+1.14- atoms. There are one shorter (2.36 Å) and one longer (2.49 Å) Si–Si bond lengths. In the third Si+1.14- site, Si+1.14- is bonded in a 8-coordinate geometry to three Yb2+, two Co+1.50+, and three Si+1.14- atoms. There are a spread of Si–Si bond distances ranging from 2.41–2.57 Å. In the fourth Si+1.14- site, Si+1.14- is bonded in a 5-coordinate geometry to two equivalent Yb2+, three equivalent Co+1.50+, and four Si+1.14- atoms. There are one shorter (2.61 Å) and one longer (2.62 Å) Si–Si bond lengths. In the fifth Si+1.14- site, Si+1.14- is bonded in a 8-coordinate geometry to three Yb2+, two Co+1.50+, and three Si+1.14- atoms. In the sixth Si+1.14- site, Si+1.14- is bonded in a 8-coordinate geometry to three Yb2+, two Co+1.50+, and three Si+1.14- atoms. In the seventh Si+1.14- site, Si+1.14- is bonded in a 8-coordinate geometry to six Yb2+ and two Si+1.14- atoms. The Si–Si bond length is 2.32 Å.