Ti5Al2C3 is H-Phase-like structured and crystallizes in the trigonal R-3m space group. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to six equivalent C(1) atoms to form edge-sharing TiC6 octahedra. In the second Ti site, Ti(2) is bonded in a 3-coordinate geometry to three equivalent Al(1) and three equivalent C(1) atoms. In the third Ti site, Ti(3) is bonded in a 3-coordinate geometry to three equivalent Al(1) and three equivalent C(2) atoms. Al(1) is bonded to three equivalent Ti(2), three equivalent Ti(3), and six equivalent Al(1) atoms to form distorted AlTi6Al6 cuboctahedra that share corners with six equivalent Al(1)Ti6Al6 cuboctahedra, corners with three equivalent C(1)Ti6 octahedra, corners with three equivalent C(2)Ti6 octahedra, edges with six equivalent Al(1)Ti6Al6 cuboctahedra, edges with three equivalent C(1)Ti6 octahedra, edges with three equivalent C(2)Ti6 octahedra, and faces with six equivalent Al(1)Ti6Al6 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-22°. There are two inequivalent C sites. In the first C site, C(1) is bonded to three equivalent Ti(1) and three equivalent Ti(2) atoms to form CTi6 octahedra that share corners with three equivalent Al(1)Ti6Al6 cuboctahedra, corners with three equivalent C(1)Ti6 octahedra, edges with three equivalent Al(1)Ti6Al6 cuboctahedra, and edges with nine equivalent C(1)Ti6 octahedra. The corner-sharing octahedra are not tilted. In the second C site, C(2) is bonded to six equivalent Ti(3) atoms to form CTi6 octahedra that share corners with six equivalent Al(1)Ti6Al6 cuboctahedra, edges with six equivalent Al(1)Ti6Al6 cuboctahedra, and edges with six equivalent C(2)Ti6 octahedra.
Ti5Al2C3 is H-Phase-like structured and crystallizes in the trigonal R-3m space group. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to six equivalent C(1) atoms to form edge-sharing TiC6 octahedra. All Ti(1)-C(1) bond lengths are 2.20 Å. In the second Ti site, Ti(2) is bonded in a 3-coordinate geometry to three equivalent Al(1) and three equivalent C(1) atoms. All Ti(2)-Al(1) bond lengths are 2.92 Å. All Ti(2)-C(1) bond lengths are 2.07 Å. In the third Ti site, Ti(3) is bonded in a 3-coordinate geometry to three equivalent Al(1) and three equivalent C(2) atoms. All Ti(3)-Al(1) bond lengths are 2.90 Å. All Ti(3)-C(2) bond lengths are 2.11 Å. Al(1) is bonded to three equivalent Ti(2), three equivalent Ti(3), and six equivalent Al(1) atoms to form distorted AlTi6Al6 cuboctahedra that share corners with six equivalent Al(1)Ti6Al6 cuboctahedra, corners with three equivalent C(1)Ti6 octahedra, corners with three equivalent C(2)Ti6 octahedra, edges with six equivalent Al(1)Ti6Al6 cuboctahedra, edges with three equivalent C(1)Ti6 octahedra, edges with three equivalent C(2)Ti6 octahedra, and faces with six equivalent Al(1)Ti6Al6 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-22°. All Al(1)-Al(1) bond lengths are 3.07 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded to three equivalent Ti(1) and three equivalent Ti(2) atoms to form CTi6 octahedra that share corners with three equivalent Al(1)Ti6Al6 cuboctahedra, corners with three equivalent C(1)Ti6 octahedra, edges with three equivalent Al(1)Ti6Al6 cuboctahedra, and edges with nine equivalent C(1)Ti6 octahedra. The corner-sharing octahedra are not tilted. In the second C site, C(2) is bonded to six equivalent Ti(3) atoms to form CTi6 octahedra that share corners with six equivalent Al(1)Ti6Al6 cuboctahedra, edges with six equivalent Al(1)Ti6Al6 cuboctahedra, and edges with six equivalent C(2)Ti6 octahedra.