DOE OSTI2020
Tb4Si7 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are four inequivalent Tb3+ sites. In the first Tb3+ site, Tb3+ is bonded in a 8-coordinate geometry to nine Si+1.71- atoms. There are a spread of Tb–Si bond distances ranging from 2.93–3.32 Å. In the second Tb3+ site, Tb3+ is bonded to twelve Si+1.71- atoms to form a mixture of face and edge-sharing TbSi12 cuboctahedra. There are a spread of Tb–Si bond distances ranging from 3.04–3.27 Å. In the third Tb3+ site, Tb3+ is bonded in a 8-coordinate geometry to nine Si+1.71- atoms. There are a spread of Tb–Si bond distances ranging from 2.93–3.31 Å. In the fourth Tb3+ site, Tb3+ is bonded to twelve Si+1.71- atoms to form a mixture of face and edge-sharing TbSi12 cuboctahedra. There are a spread of Tb–Si bond distances ranging from 3.04–3.27 Å. There are seven inequivalent Si+1.71- sites. In the first Si+1.71- site, Si+1.71- is bonded in a 9-coordinate geometry to six Tb3+ and three Si+1.71- atoms. There are a spread of Si–Si bond distances ranging from 2.34–2.40 Å. In the second Si+1.71- site, Si+1.71- is bonded in a 9-coordinate geometry to six Tb3+ and three Si+1.71- atoms. There are one shorter (2.34 Å) and one longer (2.41 Å) Si–Si bond lengths. In the third Si+1.71- site, Si+1.71- is bonded in a 9-coordinate geometry to six Tb3+ and three Si+1.71- atoms. There are one shorter (2.37 Å) and one longer (2.40 Å) Si–Si bond lengths. In the fourth Si+1.71- site, Si+1.71- is bonded in a 8-coordinate geometry to six Tb3+ and two Si+1.71- atoms. In the fifth Si+1.71- site, Si+1.71- is bonded in a 9-coordinate geometry to six Tb3+ and three Si+1.71- atoms. Both Si–Si bond lengths are 2.33 Å. In the sixth Si+1.71- site, Si+1.71- is bonded in a 8-coordinate geometry to six Tb3+ and two Si+1.71- atoms. The Si–Si bond length is 2.47 Å. In the seventh Si+1.71- site, Si+1.71- is bonded in a 9-coordinate geometry to six Tb3+ and three Si+1.71- atoms. The Si–Si bond length is 2.33 Å.