TcAl3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. Tc(1) is bonded to four equivalent Al(2) and eight equivalent Al(1) atoms to form TcAl12 cuboctahedra that share corners with four equivalent Tc(1)Al12 cuboctahedra, corners with eight equivalent Al(2)Al8Tc4 cuboctahedra, edges with eight equivalent Tc(1)Al12 cuboctahedra, edges with sixteen equivalent Al(1)Al8Tc4 cuboctahedra, faces with four equivalent Tc(1)Al12 cuboctahedra, faces with six equivalent Al(2)Al8Tc4 cuboctahedra, and faces with eight equivalent Al(1)Al8Tc4 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Tc(1), four equivalent Al(1), and four equivalent Al(2) atoms to form AlAl8Tc4 cuboctahedra that share corners with twelve equivalent Al(1)Al8Tc4 cuboctahedra, edges with eight equivalent Tc(1)Al12 cuboctahedra, edges with eight equivalent Al(1)Al8Tc4 cuboctahedra, edges with eight equivalent Al(2)Al8Tc4 cuboctahedra, faces with four equivalent Tc(1)Al12 cuboctahedra, faces with four equivalent Al(2)Al8Tc4 cuboctahedra, and faces with ten equivalent Al(1)Al8Tc4 cuboctahedra. In the second Al site, Al(2) is bonded to four equivalent Tc(1) and eight equivalent Al(1) atoms to form distorted AlAl8Tc4 cuboctahedra that share corners with four equivalent Al(2)Al8Tc4 cuboctahedra, corners with eight equivalent Tc(1)Al12 cuboctahedra, edges with eight equivalent Al(2)Al8Tc4 cuboctahedra, edges with sixteen equivalent Al(1)Al8Tc4 cuboctahedra, faces with four equivalent Al(2)Al8Tc4 cuboctahedra, faces with six equivalent Tc(1)Al12 cuboctahedra, and faces with eight equivalent Al(1)Al8Tc4 cuboctahedra.
TcAl3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. Tc(1) is bonded to four equivalent Al(2) and eight equivalent Al(1) atoms to form TcAl12 cuboctahedra that share corners with four equivalent Tc(1)Al12 cuboctahedra, corners with eight equivalent Al(2)Al8Tc4 cuboctahedra, edges with eight equivalent Tc(1)Al12 cuboctahedra, edges with sixteen equivalent Al(1)Al8Tc4 cuboctahedra, faces with four equivalent Tc(1)Al12 cuboctahedra, faces with six equivalent Al(2)Al8Tc4 cuboctahedra, and faces with eight equivalent Al(1)Al8Tc4 cuboctahedra. All Tc(1)-Al(2) bond lengths are 2.70 Å. All Tc(1)-Al(1) bond lengths are 2.75 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Tc(1), four equivalent Al(1), and four equivalent Al(2) atoms to form AlAl8Tc4 cuboctahedra that share corners with twelve equivalent Al(1)Al8Tc4 cuboctahedra, edges with eight equivalent Tc(1)Al12 cuboctahedra, edges with eight equivalent Al(1)Al8Tc4 cuboctahedra, edges with eight equivalent Al(2)Al8Tc4 cuboctahedra, faces with four equivalent Tc(1)Al12 cuboctahedra, faces with four equivalent Al(2)Al8Tc4 cuboctahedra, and faces with ten equivalent Al(1)Al8Tc4 cuboctahedra. All Al(1)-Al(1) bond lengths are 2.70 Å. All Al(1)-Al(2) bond lengths are 2.75 Å. In the second Al site, Al(2) is bonded to four equivalent Tc(1) and eight equivalent Al(1) atoms to form distorted AlAl8Tc4 cuboctahedra that share corners with four equivalent Al(2)Al8Tc4 cuboctahedra, corners with eight equivalent Tc(1)Al12 cuboctahedra, edges with eight equivalent Al(2)Al8Tc4 cuboctahedra, edges with sixteen equivalent Al(1)Al8Tc4 cuboctahedra, faces with four equivalent Al(2)Al8Tc4 cuboctahedra, faces with six equivalent Tc(1)Al12 cuboctahedra, and faces with eight equivalent Al(1)Al8Tc4 cuboctahedra.