DOE OSTI2020
Fe3Ge is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are three inequivalent Fe sites. In the first Fe site, Fe is bonded to eight Fe and four equivalent Ge atoms to form FeFe8Ge4 cuboctahedra that share corners with four equivalent GeFe12 cuboctahedra, corners with fourteen FeFe8Ge4 cuboctahedra, edges with six equivalent GeFe12 cuboctahedra, edges with twelve FeFe8Ge4 cuboctahedra, faces with four equivalent GeFe12 cuboctahedra, and faces with sixteen FeFe8Ge4 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.51–2.64 Å. There are two shorter (2.57 Å) and two longer (2.60 Å) Fe–Ge bond lengths. In the second Fe site, Fe is bonded to eight Fe and four equivalent Ge atoms to form FeFe8Ge4 cuboctahedra that share corners with four equivalent GeFe12 cuboctahedra, corners with fourteen FeFe8Ge4 cuboctahedra, edges with six equivalent GeFe12 cuboctahedra, edges with twelve FeFe8Ge4 cuboctahedra, faces with four equivalent GeFe12 cuboctahedra, and faces with sixteen FeFe8Ge4 cuboctahedra. There are one shorter (2.51 Å) and one longer (2.64 Å) Fe–Fe bond lengths. There are two shorter (2.57 Å) and two longer (2.60 Å) Fe–Ge bond lengths. In the third Fe site, Fe is bonded to eight Fe and four equivalent Ge atoms to form FeFe8Ge4 cuboctahedra that share corners with four equivalent GeFe12 cuboctahedra, corners with fourteen FeFe8Ge4 cuboctahedra, edges with six equivalent GeFe12 cuboctahedra, edges with twelve FeFe8Ge4 cuboctahedra, faces with four equivalent GeFe12 cuboctahedra, and faces with sixteen FeFe8Ge4 cuboctahedra. There are two shorter (2.57 Å) and two longer (2.60 Å) Fe–Ge bond lengths. Ge is bonded to twelve Fe atoms to form GeFe12 cuboctahedra that share corners with six equivalent GeFe12 cuboctahedra, corners with twelve FeFe8Ge4 cuboctahedra, edges with eighteen FeFe8Ge4 cuboctahedra, faces with eight equivalent GeFe12 cuboctahedra, and faces with twelve FeFe8Ge4 cuboctahedra.