Materials Data on U6Al43Cr4 by Materials Project

Abstract

U6Cr4Al43 is Hexagonal Laves-derived structured and crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. U is bonded in a 2-coordinate geometry to one U, one Cr, and fifteen Al atoms. The U–U bond length is 3.02 Å. The U–Cr bond length is 3.65 Å. There are a spread of U–Al bond distances ranging from 3.00–3.52 Å. There are two inequivalent Cr sites. In the first Cr site, Cr is bonded in a distorted q6 geometry to two equivalent U and ten Al atoms. There are a spread of Cr–Al bond distances ranging from 2.52–2.64 Å. In the second Cr site, Cr is bonded to twelve Al atoms to form CrAl12 cuboctahedra that share faces with six equivalent AlU2Al9Cr cuboctahedra. There are six shorter (2.63 Å) and six longer (2.79 Å) Cr–Al bond lengths. There are seven inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to one U, two Cr, and nine Al atoms. There are a spread of Al–Al bond distances ranging from 2.68–2.98 Å. In the second Al site, Al is bonded in a 12-coordinate geometry to four equivalent U and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.71–3.03 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent U, one Cr, and nine Al atoms. There are a spread of Al–Al bond distances ranging from 2.69–3.05 Å. In the fourth Al site, Al is bonded in a 2-coordinate geometry to two equivalent Cr and ten Al atoms. Both Al–Al bond lengths are 2.78 Å. In the fifth Al site, Al is bonded to two equivalent U, one Cr, and nine Al atoms to form distorted AlU2Al9Cr cuboctahedra that share a cornercorner with one AlU2Al9Cr cuboctahedra, edges with three AlU2Al9Cr cuboctahedra, a faceface with one CrAl12 cuboctahedra, and faces with six AlU2Al9Cr cuboctahedra. Both Al–Al bond lengths are 2.92 Å. In the sixth Al site, Al is bonded to three equivalent U and nine Al atoms to form AlU3Al9 cuboctahedra that share corners with three equivalent AlU3Al9 cuboctahedra, edges with three equivalent AlU2Al9Cr cuboctahedra, and faces with five AlU2Al9Cr cuboctahedra. All Al–Al bond lengths are 2.80 Å. In the seventh Al site, Al is bonded in a 10-coordinate geometry to two equivalent U, one Cr, and seven Al atoms. The Al–Al bond length is 2.64 Å.