DOE OSTI2020
Dy2Fe15Si2C crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Dy is bonded in a distorted single-bond geometry to thirteen Fe, one Si, and one C atom. There are a spread of Dy–Fe bond distances ranging from 2.91–3.33 Å. The Dy–Si bond length is 3.07 Å. The Dy–C bond length is 2.48 Å. There are six inequivalent Fe sites. In the first Fe site, Fe is bonded in a single-bond geometry to six Fe, one Si, and one C atom. There are a spread of Fe–Fe bond distances ranging from 2.43–2.59 Å. The Fe–Si bond length is 2.60 Å. The Fe–C bond length is 1.92 Å. In the second Fe site, Fe is bonded to three equivalent Dy, eight Fe, and one Si atom to form FeDy3Fe8Si cuboctahedra that share corners with twelve FeDy3Fe8Si cuboctahedra, corners with two equivalent CDy2Fe4 octahedra, edges with six FeDy3Fe8Si cuboctahedra, faces with seven FeDy3Fe8Si cuboctahedra, and a faceface with one CDy2Fe4 octahedra. The corner-sharing octahedra tilt angles range from 65–71°. There are a spread of Fe–Fe bond distances ranging from 2.40–2.60 Å. The Fe–Si bond length is 2.57 Å. In the third Fe site, Fe is bonded to two equivalent Dy, eight Fe, and two equivalent Si atoms to form distorted FeDy2Fe8Si2 cuboctahedra that share corners with eight FeDy3Fe8Si cuboctahedra, corners with two equivalent CDy2Fe4 octahedra, edges with four equivalent FeDy3Fe8Si cuboctahedra, and faces with eight FeDy3Fe8Si cuboctahedra. The corner-sharing octahedral tilt angles are 47°. All Fe–Fe bond lengths are 2.46 Å. Both Fe–Si bond lengths are 2.58 Å. In the fourth Fe site, Fe is bonded to two equivalent Dy, eight Fe, and two equivalent Si atoms to form distorted FeDy2Fe8Si2 cuboctahedra that share corners with twelve FeDy3Fe8Si cuboctahedra, edges with four equivalent FeDy3Fe8Si cuboctahedra, faces with eight FeDy3Fe8Si cuboctahedra, and faces with two equivalent CDy2Fe4 octahedra. There are two shorter (2.44 Å) and two longer (2.45 Å) Fe–Fe bond lengths. Both Fe–Si bond lengths are 2.56 Å. In the fifth Fe site, Fe is bonded in a single-bond geometry to six Fe, two equivalent Si, and one C atom. Both Fe–Fe bond lengths are 2.47 Å. Both Fe–Si bond lengths are 2.69 Å. The Fe–C bond length is 1.85 Å. In the sixth Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Dy, eight Fe, and two equivalent Si atoms. The Fe–Fe bond length is 2.52 Å. There are one shorter (2.83 Å) and one longer (2.87 Å) Fe–Si bond lengths. Si is bonded in a 10-coordinate geometry to one Dy, twelve Fe, and one Si atom. The Si–Si bond length is 2.55 Å. C is bonded to two equivalent Dy and four Fe atoms to form CDy2Fe4 octahedra that share corners with ten FeDy2Fe8Si2 cuboctahedra and faces with eight FeDy2Fe8Si2 cuboctahedra.