DOE OSTI2020
Pr4Co25Al crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. there are two inequivalent Pr sites. In the first Pr site, Pr is bonded in a 6-coordinate geometry to eighteen Co atoms. There are a spread of Pr–Co bond distances ranging from 2.88–3.21 Å. In the second Pr site, Pr is bonded in a 6-coordinate geometry to eighteen Co atoms. There are a spread of Pr–Co bond distances ranging from 2.81–3.22 Å. There are eleven inequivalent Co sites. In the first Co site, Co is bonded in a 1-coordinate geometry to two equivalent Pr, eight Co, and one Al atom. There are a spread of Co–Co bond distances ranging from 2.36–2.72 Å. The Co–Al bond length is 2.41 Å. In the second Co site, Co is bonded in a 12-coordinate geometry to three Pr and eight Co atoms. There are a spread of Co–Co bond distances ranging from 2.44–2.78 Å. In the third Co site, Co is bonded in a 12-coordinate geometry to three equivalent Pr and six Co atoms. There are four shorter (2.45 Å) and two longer (2.48 Å) Co–Co bond lengths. In the fourth Co site, Co is bonded in a 3-coordinate geometry to three Pr and eight Co atoms. There are four shorter (2.42 Å) and two longer (2.52 Å) Co–Co bond lengths. In the fifth Co site, Co is bonded to one Pr, nine Co, and two equivalent Al atoms to form a mixture of distorted edge, face, and corner-sharing CoPrAl2Co9 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.35–2.48 Å. Both Co–Al bond lengths are 2.74 Å. In the sixth Co site, Co is bonded to four equivalent Pr and eight Co atoms to form CoPr4Co8 cuboctahedra that share corners with sixteen CoPr4Co8 cuboctahedra, edges with ten CoPr2Al2Co8 cuboctahedra, and faces with fourteen CoPrAl2Co9 cuboctahedra. There are two shorter (2.47 Å) and two longer (2.49 Å) Co–Co bond lengths. In the seventh Co site, Co is bonded to four equivalent Pr and eight Co atoms to form a mixture of edge, face, and corner-sharing CoPr4Co8 cuboctahedra. All Co–Co bond lengths are 2.51 Å. In the eighth Co site, Co is bonded to eight Co atoms to form distorted CoCo8 cuboctahedra that share corners with sixteen CoPr2Al2Co8 cuboctahedra, edges with two equivalent CoCo8 cuboctahedra, and faces with eight CoPr2Al2Co8 cuboctahedra. All Co–Co bond lengths are 2.35 Å. In the ninth Co site, Co is bonded to two equivalent Pr, eight Co, and two equivalent Al atoms to form CoPr2Al2Co8 cuboctahedra that share corners with nineteen CoPrAl2Co9 cuboctahedra, edges with eight CoPr4Co8 cuboctahedra, and faces with fifteen CoPrAl2Co9 cuboctahedra. There are one shorter (2.39 Å) and one longer (2.51 Å) Co–Co bond lengths. Both Co–Al bond lengths are 3.06 Å. In the tenth Co site, Co is bonded to four Pr and eight Co atoms to form CoPr4Co8 cuboctahedra that share corners with eighteen CoPrAl2Co9 cuboctahedra, edges with ten CoPr4Co8 cuboctahedra, and faces with ten CoPr4Co8 cuboctahedra. There are one shorter (2.43 Å) and one longer (2.47 Å) Co–Co bond lengths. In the eleventh Co site, Co is bonded to four equivalent Pr and eight Co atoms to form a mixture of edge, face, and corner-sharing CoPr4Co8 cuboctahedra. Both Co–Co bond lengths are 2.45 Å. Al is bonded in a 2-coordinate geometry to fourteen Co atoms.