Materials Data on TiAl2 by Materials Project
TiAl2 is beta Cu3Ti-like structured and crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Ti is bonded to two equivalent Ti and ten Al atoms to form distorted TiTi2Al10 cuboctahedra that share corners with four equivalent AlTi4Al8 cuboctahedra, corners with eight equivalent TiTi2Al10 cuboctahedra, edges with four equivalent TiTi2Al10 cuboctahedra, edges with twenty AlTi4Al8 cuboctahedra, faces with seven equivalent TiTi2Al10 cuboctahedra, and faces with eleven AlTi4Al8 cuboctahedra. Both Ti–Ti bond lengths are 3.01 Å. There are a spread of Ti–Al bond distances ranging from 2.73–2.89 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Ti and eight Al atoms to form AlTi4Al8 cuboctahedra that share corners with four equivalent AlTi4Al8 cuboctahedra, corners with eight equivalent TiTi2Al10 cuboctahedra, edges with eight equivalent TiTi2Al10 cuboctahedra, edges with sixteen equivalent AlTi6Al6 cuboctahedra, faces with six equivalent TiTi2Al10 cuboctahedra, and faces with twelve AlTi4Al8 cuboctahedra. There are four shorter (2.81 Å) and four longer (2.90 Å) Al–Al bond lengths. In the second Al site, Al is bonded to four equivalent Ti and eight Al atoms to form AlTi4Al8 cuboctahedra that share corners with twelve AlTi4Al8 cuboctahedra, edges with eight equivalent AlTi6Al6 cuboctahedra, edges with sixteen equivalent TiTi2Al10 cuboctahedra, faces with four equivalent TiTi2Al10 cuboctahedra, and faces with fourteen AlTi4Al8 cuboctahedra. All Al–Al bond lengths are 2.88 Å. In the third Al site, Al is bonded to six equivalent Ti and six Al atoms to form AlTi6Al6 cuboctahedra that share corners with twelve AlTi4Al8 cuboctahedra, edges with eight equivalent TiTi2Al10 cuboctahedra, edges with sixteen AlTi4Al8 cuboctahedra, faces with six equivalent TiTi2Al10 cuboctahedra, and faces with twelve AlTi4Al8 cuboctahedra. Both Al–Al bond lengths are 2.72 Å.