Materials Data on U6Fe16Si7C by Materials Project
U6Fe16Si7C crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. U is bonded in a distorted single-bond geometry to eight Fe, four equivalent Si, and one C atom. There are four shorter (2.76 Å) and four longer (2.90 Å) U–Fe bond lengths. All U–Si bond lengths are 2.92 Å. The U–C bond length is 2.48 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 10-coordinate geometry to three equivalent U, six Fe, and four Si atoms. There are three shorter (2.50 Å) and three longer (2.83 Å) Fe–Fe bond lengths. There are one shorter (2.46 Å) and three longer (2.52 Å) Fe–Si bond lengths. In the second Fe site, Fe is bonded in a 12-coordinate geometry to three equivalent U, six Fe, and three equivalent Si atoms. All Fe–Fe bond lengths are 2.46 Å. All Fe–Si bond lengths are 2.37 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a body-centered cubic geometry to eight equivalent Fe atoms. In the second Si site, Si is bonded to four equivalent U and eight Fe atoms to form SiU4Fe8 cuboctahedra that share corners with four equivalent SiU4Fe8 cuboctahedra, edges with two equivalent CU6 octahedra, and faces with eight equivalent SiU4Fe8 cuboctahedra. C is bonded to six equivalent U atoms to form CU6 octahedra that share edges with twelve equivalent SiU4Fe8 cuboctahedra.