Ta4AlN3 is MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to three equivalent N(1) and three equivalent N(2) atoms to form a mixture of distorted corner and edge-sharing TaN6 pentagonal pyramids. In the second Ta site, Ta(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 Ta(2) and six equivalent Al(1) atoms to form distorted AlTa6Al6 cuboctahedra that share corners with six equivalent Al(1)Ta6Al6 cuboctahedra, corners with six equivalent N(2)Ta6 octahedra, edges with six equivalent Al(1)Ta6Al6 cuboctahedra, edges with six equivalent N(2)Ta6 octahedra, and faces with six equivalent Al(1)Ta6Al6 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. There are two inequivalent N sites. In the first N site, N(1) is bonded to six equivalent Ta(1) atoms to form a mixture of face, corner, and edge-sharing NTa6 octahedra. The corner-sharing octahedral tilt angles are 46°. In the second N site, N(2) is bonded to three equivalent Ta(1) and three equivalent Ta(2) atoms to form NTa6 octahedra that share corners with three equivalent Al(1)Ta6Al6 cuboctahedra, corners with six equivalent N(1)Ta6 octahedra, edges with three equivalent Al(1)Ta6Al6 cuboctahedra, edges with six equivalent N(2)Ta6 octahedra, and  a faceface with one N(1)Ta6 octahedra. The corner-sharing octahedral tilt angles are 46°.
Ta4AlN3 is MAX Phase-like structured and crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to three equivalent N(1) and three equivalent N(2) atoms to form a mixture of distorted corner and edge-sharing TaN6 pentagonal pyramids. All Ta(1)-N(1) bond lengths are 2.23 Å. All Ta(1)-N(2) bond lengths are 2.21 Å. In the second Ta site, Ta(2) is bonded in a 3-coordinate geometry to three equivalent Al(1) and three equivalent N(2) atoms. All Ta(2)-Al(1) bond lengths are 2.81 Å. All Ta(2)-N(2) bond lengths are 2.23 Å. Al(1) is bonded to six equivalent Ta(2) and six equivalent Al(1) atoms to form distorted AlTa6Al6 cuboctahedra that share corners with six equivalent Al(1)Ta6Al6 cuboctahedra, corners with six equivalent N(2)Ta6 octahedra, edges with six equivalent Al(1)Ta6Al6 cuboctahedra, edges with six equivalent N(2)Ta6 octahedra, and faces with six equivalent Al(1)Ta6Al6 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. All Al(1)-Al(1) bond lengths are 2.98 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded to six equivalent Ta(1) atoms to form a mixture of face, corner, and edge-sharing NTa6 octahedra. The corner-sharing octahedral tilt angles are 46°. In the second N site, N(2) is bonded to three equivalent Ta(1) and three equivalent Ta(2) atoms to form NTa6 octahedra that share corners with three equivalent Al(1)Ta6Al6 cuboctahedra, corners with six equivalent N(1)Ta6 octahedra, edges with three equivalent Al(1)Ta6Al6 cuboctahedra, edges with six equivalent N(2)Ta6 octahedra, and  a faceface with one N(1)Ta6 octahedra. The corner-sharing octahedral tilt angles are 46°.