DOE OSTI2020
TbCo4Al crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Tb is bonded in a distorted hexagonal planar geometry to fourteen Co and four equivalent Al atoms. There are a spread of Tb–Co bond distances ranging from 2.84–3.18 Å. All Tb–Al bond lengths are 3.17 Å. There are two inequivalent Co sites. In the first Co site, Co is bonded in a 12-coordinate geometry to three equivalent Tb, four equivalent Co, and two equivalent Al atoms. All Co–Co bond lengths are 2.45 Å. Both Co–Al bond lengths are 2.48 Å. In the second Co site, Co is bonded to four equivalent Tb, six Co, and two equivalent Al atoms to form distorted CoTb4Al2Co6 cuboctahedra that share corners with four equivalent AlTb4Co8 cuboctahedra, corners with twelve equivalent CoTb4Al2Co6 cuboctahedra, edges with four equivalent AlTb4Co8 cuboctahedra, edges with six equivalent CoTb4Al2Co6 cuboctahedra, faces with four equivalent AlTb4Co8 cuboctahedra, and faces with six equivalent CoTb4Al2Co6 cuboctahedra. Both Co–Co bond lengths are 2.45 Å. Both Co–Al bond lengths are 2.47 Å. Al is bonded to four equivalent Tb and eight Co atoms to form distorted AlTb4Co8 cuboctahedra that share corners with eight equivalent CoTb4Al2Co6 cuboctahedra, corners with eight equivalent AlTb4Co8 cuboctahedra, edges with two equivalent AlTb4Co8 cuboctahedra, edges with eight equivalent CoTb4Al2Co6 cuboctahedra, faces with two equivalent AlTb4Co8 cuboctahedra, and faces with eight equivalent CoTb4Al2Co6 cuboctahedra.