Nb4Al crystallizes in the orthorhombic Fmmm space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 8-coordinate geometry to two equivalent Nb(2), four equivalent Nb(1), and four equivalent Al(1) atoms. In the second Nb site, Nb(2) is bonded in a distorted body-centered cubic geometry to two equivalent Nb(1) and six equivalent Nb(2) atoms. Al(1) is bonded to eight equivalent Nb(1) and four equivalent Al(1) atoms to form a mixture of distorted face and corner-sharing AlNb8Al4 cuboctahedra.
Nb4Al crystallizes in the orthorhombic Fmmm space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded in a 8-coordinate geometry to two equivalent Nb(2), four equivalent Nb(1), and four equivalent Al(1) atoms. Both Nb(1)-Nb(2) bond lengths are 2.94 Å. All Nb(1)-Nb(1) bond lengths are 2.83 Å. There are two shorter (2.80 Å) and two longer (3.16 Å) Nb(1)-Al(1) bond lengths. In the second Nb site, Nb(2) is bonded in a distorted body-centered cubic geometry to two equivalent Nb(1) and six equivalent Nb(2) atoms. There are four shorter (2.83 Å) and two longer (2.90 Å) Nb(2)-Nb(2) bond lengths. Al(1) is bonded to eight equivalent Nb(1) and four equivalent Al(1) atoms to form a mixture of distorted face and corner-sharing AlNb8Al4 cuboctahedra. All Al(1)-Al(1) bond lengths are 2.83 Å.