Nb4AlN3 is MAX Phase structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to three equivalent N(1) and three equivalent N(2) atoms to form a mixture of edge and corner-sharing NbN6 octahedra. The corner-sharing octahedra are not tilted. In the second Nb site, Nb(2) is bonded in a 3-coordinate geometry to three equivalent Al(1) and three equivalent N(2) atoms. Al(1) is bonded to six equivalent Nb(2) atoms to form distorted AlNb6 cuboctahedra that share corners with six equivalent N(2)Nb6 octahedra, edges with six equivalent Al(1)Nb6 cuboctahedra, and edges with six equivalent N(2)Nb6 octahedra. The corner-sharing octahedral tilt angles are 16°. There are two inequivalent N sites. In the first N site, N(1) is bonded to six equivalent Nb(1) atoms to form a mixture of edge and corner-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles are 2°. In the second N site, N(2) is bonded to three equivalent Nb(1) and three equivalent Nb(2) atoms to form NNb6 octahedra that share corners with three equivalent Al(1)Nb6 cuboctahedra, corners with three equivalent N(1)Nb6 octahedra, edges with three equivalent Al(1)Nb6 cuboctahedra, edges with three equivalent N(1)Nb6 octahedra, and edges with six equivalent N(2)Nb6 octahedra. The corner-sharing octahedral tilt angles are 2°.
Nb4AlN3 is MAX Phase structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to three equivalent N(1) and three equivalent N(2) atoms to form a mixture of edge and corner-sharing NbN6 octahedra. The corner-sharing octahedra are not tilted. All Nb(1)-N(1) bond lengths are 2.19 Å. All Nb(1)-N(2) bond lengths are 2.25 Å. In the second Nb site, Nb(2) is bonded in a 3-coordinate geometry to three equivalent Al(1) and three equivalent N(2) atoms. All Nb(2)-Al(1) bond lengths are 2.85 Å. All Nb(2)-N(2) bond lengths are 2.20 Å. Al(1) is bonded to six equivalent Nb(2) atoms to form distorted AlNb6 cuboctahedra that share corners with six equivalent N(2)Nb6 octahedra, edges with six equivalent Al(1)Nb6 cuboctahedra, and edges with six equivalent N(2)Nb6 octahedra. The corner-sharing octahedral tilt angles are 16°. There are two inequivalent N sites. In the first N site, N(1) is bonded to six equivalent Nb(1) atoms to form a mixture of edge and corner-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles are 2°. In the second N site, N(2) is bonded to three equivalent Nb(1) and three equivalent Nb(2) atoms to form NNb6 octahedra that share corners with three equivalent Al(1)Nb6 cuboctahedra, corners with three equivalent N(1)Nb6 octahedra, edges with three equivalent Al(1)Nb6 cuboctahedra, edges with three equivalent N(1)Nb6 octahedra, and edges with six equivalent N(2)Nb6 octahedra. The corner-sharing octahedral tilt angles are 2°.