Materials Data on U2Al3Si by Materials Project
U2Al3Si crystallizes in the trigonal R-3m space group. The structure is three-dimensional. U is bonded in a 12-coordinate geometry to four equivalent U, nine equivalent Al, and three equivalent Si atoms. There are three shorter (3.29 Å) and one longer (3.30 Å) U–U bond lengths. There are six shorter (3.15 Å) and three longer (3.16 Å) U–Al bond lengths. All U–Si bond lengths are 3.14 Å. Al is bonded to six equivalent U, four equivalent Al, and two equivalent Si atoms to form AlU6Al4Si2 cuboctahedra that share corners with four equivalent SiU6Al6 cuboctahedra, corners with fourteen equivalent AlU6Al4Si2 cuboctahedra, edges with six equivalent AlU6Al4Si2 cuboctahedra, faces with six equivalent SiU6Al6 cuboctahedra, and faces with twelve equivalent AlU6Al4Si2 cuboctahedra. All Al–Al bond lengths are 2.68 Å. Both Al–Si bond lengths are 2.69 Å. Si is bonded to six equivalent U and six equivalent Al atoms to form SiU6Al6 cuboctahedra that share corners with six equivalent SiU6Al6 cuboctahedra, corners with twelve equivalent AlU6Al4Si2 cuboctahedra, edges with six equivalent SiU6Al6 cuboctahedra, and faces with eighteen equivalent AlU6Al4Si2 cuboctahedra.