Materials Data on U2(AlSi)3 by Materials Project

Abstract

U2(AlSi)3 crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. U is bonded to six Al and six Si atoms to form UAl6Si6 cuboctahedra that share corners with twelve equivalent UAl6Si6 cuboctahedra, edges with four equivalent SiU4Al8 cuboctahedra, edges with twelve AlU4Al2Si6 cuboctahedra, faces with two equivalent SiU4Al8 cuboctahedra, faces with six equivalent UAl6Si6 cuboctahedra, and faces with six AlU4Al2Si6 cuboctahedra. All U–Al bond lengths are 2.98 Å. There are a spread of U–Si bond distances ranging from 2.83–2.95 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent U, two equivalent Al, and six Si atoms to form AlU4Al2Si6 cuboctahedra that share corners with twelve equivalent AlU4Al2Si6 cuboctahedra, edges with four equivalent AlU4Al4Si4 cuboctahedra, edges with four equivalent SiU4Al8 cuboctahedra, edges with eight equivalent UAl6Si6 cuboctahedra, faces with two equivalent SiU4Al8 cuboctahedra, faces with four equivalent UAl6Si6 cuboctahedra, and faces with eight AlU4Al2Si6 cuboctahedra. Both Al–Al bond lengths are 2.89 Å. There are a spread of Al–Si bond distances ranging from 2.88–2.93 Å. In the second Al site, Al is bonded to four equivalent U, four equivalent Al, and four equivalent Si atoms to form AlU4Al4Si4 cuboctahedra that share corners with four equivalent AlU4Al4Si4 cuboctahedra, edges with eight equivalent UAl6Si6 cuboctahedra, edges with eight equivalent AlU4Al2Si6 cuboctahedra, faces with four equivalent UAl6Si6 cuboctahedra, faces with four equivalent SiU4Al8 cuboctahedra, and faces with eight AlU4Al2Si6 cuboctahedra. All Al–Si bond lengths are 2.98 Å. There are three inequivalent Si sites. In the first Si site, Si is bonded in a distorted body-centered cubic geometry to four equivalent U and four equivalent Al atoms. In the second Si site, Si is bonded to four equivalent U and eight Al atoms to form SiU4Al8 cuboctahedra that share corners with four equivalent SiU4Al8 cuboctahedra, edges with eight equivalent UAl6Si6 cuboctahedra, edges with eight equivalent AlU4Al2Si6 cuboctahedra, faces with four equivalent UAl6Si6 cuboctahedra, faces with four equivalent SiU4Al8 cuboctahedra, and faces with eight AlU4Al2Si6 cuboctahedra. In the third Si site, Si is bonded in a distorted body-centered cubic geometry to four equivalent U and four equivalent Al atoms.