Materials Data on U4SiNi7 by Materials Project
U4Ni7Si is Hexagonal Laves-derived structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are two inequivalent U sites. In the first U site, U is bonded in a 12-coordinate geometry to four U, nine equivalent Ni, and three equivalent Si atoms. There are one shorter (2.79 Å) and three longer (3.20 Å) U–U bond lengths. There are six shorter (2.85 Å) and three longer (2.96 Å) U–Ni bond lengths. All U–Si bond lengths are 3.00 Å. In the second U site, U is bonded in a 12-coordinate geometry to four U and twelve Ni atoms. All U–U bond lengths are 3.09 Å. There are a spread of U–Ni bond distances ranging from 2.88–2.97 Å. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded to six U, five Ni, and one Si atom to form NiU6SiNi5 cuboctahedra that share corners with two equivalent SiU6Ni6 cuboctahedra, corners with sixteen NiU6SiNi5 cuboctahedra, edges with six equivalent NiU6SiNi5 cuboctahedra, faces with three equivalent SiU6Ni6 cuboctahedra, and faces with fifteen NiU6SiNi5 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.48–2.55 Å. The Ni–Si bond length is 2.43 Å. In the second Ni site, Ni is bonded to six equivalent U and six equivalent Ni atoms to form NiU6Ni6 cuboctahedra that share corners with twelve equivalent NiU6SiNi5 cuboctahedra, edges with six equivalent NiU6Ni6 cuboctahedra, faces with two equivalent SiU6Ni6 cuboctahedra, and faces with eighteen equivalent NiU6SiNi5 cuboctahedra. Si is bonded to six equivalent U and six equivalent Ni atoms to form SiU6Ni6 cuboctahedra that share corners with twelve equivalent NiU6SiNi5 cuboctahedra, edges with six equivalent SiU6Ni6 cuboctahedra, and faces with twenty NiU6Ni6 cuboctahedra.