Materials Data on NbAlCr4 by Materials Project

Abstract

NbCr4Al is Hexagonal Laves-derived structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Nb is bonded in a 12-coordinate geometry to three equivalent Nb, twelve Cr, and one Al atom. All Nb–Nb bond lengths are 2.99 Å. There are a spread of Nb–Cr bond distances ranging from 2.84–2.88 Å. The Nb–Al bond length is 2.91 Å. There are three inequivalent Cr sites. In the first Cr site, Cr is bonded to six equivalent Cr and six equivalent Al atoms to form CrAl6Cr6 cuboctahedra that share corners with twelve equivalent CrNb3Al3Cr6 cuboctahedra, edges with six equivalent CrAl6Cr6 cuboctahedra, and faces with twenty CrNb6Cr6 cuboctahedra. All Cr–Cr bond lengths are 2.40 Å. All Cr–Al bond lengths are 2.87 Å. In the second Cr site, Cr is bonded to six equivalent Nb and six equivalent Cr atoms to form CrNb6Cr6 cuboctahedra that share corners with twelve equivalent CrNb3Al3Cr6 cuboctahedra, edges with six equivalent CrNb6Cr6 cuboctahedra, and faces with twenty CrAl6Cr6 cuboctahedra. All Cr–Cr bond lengths are 2.47 Å. In the third Cr site, Cr is bonded to three equivalent Nb, six Cr, and three equivalent Al atoms to form CrNb3Al3Cr6 cuboctahedra that share corners with eighteen CrAl6Cr6 cuboctahedra, edges with six equivalent CrNb3Al3Cr6 cuboctahedra, and faces with eighteen CrAl6Cr6 cuboctahedra. There are two shorter (2.39 Å) and two longer (2.51 Å) Cr–Cr bond lengths. There are one shorter (2.77 Å) and two longer (2.83 Å) Cr–Al bond lengths. Al is bonded in a 9-coordinate geometry to one Nb, twelve Cr, and three equivalent Al atoms. All Al–Al bond lengths are 3.00 Å.