DOE OSTI2020
Ti2ZrAl is beta-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Zr is bonded to two equivalent Zr, six Ti, and four Al atoms to form ZrZr2Ti6Al4 cuboctahedra that share corners with four equivalent TiZr4Ti4Al4 cuboctahedra, corners with four equivalent AlZr4Ti8 cuboctahedra, corners with ten equivalent ZrZr2Ti6Al4 cuboctahedra, edges with two equivalent ZrZr2Ti6Al4 cuboctahedra, edges with six AlZr4Ti8 cuboctahedra, edges with ten TiZr4Ti4Al4 cuboctahedra, faces with four equivalent ZrZr2Ti6Al4 cuboctahedra, faces with four AlZr4Ti8 cuboctahedra, and faces with twelve TiZr4Ti4Al4 cuboctahedra. There are one shorter (2.96 Å) and one longer (2.98 Å) Zr–Zr bond lengths. There are a spread of Zr–Ti bond distances ranging from 2.93–3.00 Å. There are a spread of Zr–Al bond distances ranging from 2.95–2.97 Å. There are three inequivalent Ti sites. In the first Ti site, Ti is bonded to four equivalent Zr, four equivalent Ti, and four Al atoms to form TiZr4Ti4Al4 cuboctahedra that share corners with four equivalent AlZr4Ti8 cuboctahedra, corners with six equivalent TiZr4Ti4Al4 cuboctahedra, corners with eight equivalent ZrZr2Ti6Al4 cuboctahedra, edges with four equivalent ZrZr2Ti6Al4 cuboctahedra, edges with six AlZr4Ti8 cuboctahedra, edges with eight equivalent TiZr2Ti6Al4 cuboctahedra, faces with four equivalent ZrZr2Ti6Al4 cuboctahedra, faces with four AlZr4Ti8 cuboctahedra, and faces with twelve TiZr4Ti4Al4 cuboctahedra. All Ti–Ti bond lengths are 2.95 Å. There are two shorter (2.90 Å) and two longer (2.97 Å) Ti–Al bond lengths. In the second Ti site, Ti is bonded to two equivalent Zr, six Ti, and four Al atoms to form distorted TiZr2Ti6Al4 cuboctahedra that share corners with four equivalent AlZr4Ti8 cuboctahedra, corners with fourteen TiZr2Ti6Al4 cuboctahedra, edges with four equivalent ZrZr2Ti6Al4 cuboctahedra, edges with six AlZr4Ti8 cuboctahedra, edges with eight TiZr4Ti4Al4 cuboctahedra, faces with four AlZr4Ti8 cuboctahedra, faces with eight equivalent ZrZr2Ti6Al4 cuboctahedra, and faces with eight TiZr4Ti4Al4 cuboctahedra. There are a spread of Ti–Ti bond distances ranging from 2.83–3.10 Å. There are a spread of Ti–Al bond distances ranging from 2.88–3.05 Å. In the third Ti site, Ti is bonded to four equivalent Zr, four equivalent Ti, and four Al atoms to form distorted TiZr4Ti4Al4 cuboctahedra that share corners with four equivalent AlZr4Ti8 cuboctahedra, corners with fourteen TiZr2Ti6Al4 cuboctahedra, edges with four equivalent TiZr2Ti6Al4 cuboctahedra, edges with six AlZr4Ti8 cuboctahedra, edges with eight equivalent ZrZr2Ti6Al4 cuboctahedra, faces with four equivalent ZrZr2Ti6Al4 cuboctahedra, faces with four AlZr4Ti8 cuboctahedra, and faces with twelve TiZr4Ti4Al4 cuboctahedra. There are two shorter (2.90 Å) and two longer (2.97 Å) Ti–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Zr and eight Ti atoms to form AlZr4Ti8 cuboctahedra that share corners with four equivalent TiZr4Ti4Al4 cuboctahedra, corners with six equivalent AlZr4Ti8 cuboctahedra, corners with eight equivalent ZrZr2Ti6Al4 cuboctahedra, edges with four equivalent ZrZr2Ti6Al4 cuboctahedra, edges with fourteen TiZr4Ti4Al4 cuboctahedra, faces with four equivalent ZrZr2Ti6Al4 cuboctahedra, faces with eight TiZr4Ti4Al4 cuboctahedra, and faces with eight AlZr4Ti8 cuboctahedra. In the second Al site, Al is bonded to four equivalent Zr and eight Ti atoms to form AlZr4Ti8 cuboctahedra that share corners with six equivalent AlZr4Ti8 cuboctahedra, corners with twelve TiZr2Ti6Al4 cuboctahedra, edges with eight equivalent ZrZr2Ti6Al4 cuboctahedra, edges with ten TiZr4Ti4Al4 cuboctahedra, faces with four equivalent ZrZr2Ti6Al4 cuboctahedra, faces with eight TiZr4Ti4Al4 cuboctahedra, and faces with eight AlZr4Ti8 cuboctahedra.