DOE OSTI2020
Pr3Co8Sn4 is Hexagonal Laves-derived structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Pr is bonded in a 12-coordinate geometry to eight Co and six Sn atoms. There are a spread of Pr–Co bond distances ranging from 3.17–3.62 Å. There are a spread of Pr–Sn bond distances ranging from 3.23–3.30 Å. There are four inequivalent Co sites. In the first Co site, Co is bonded in a 10-coordinate geometry to six equivalent Pr and four Sn atoms. There are three shorter (2.58 Å) and one longer (2.68 Å) Co–Sn bond lengths. In the second Co site, Co is bonded to two equivalent Pr, seven Co, and three equivalent Sn atoms to form CoPr2Co7Sn3 cuboctahedra that share corners with four equivalent CoPr2Co7Sn3 cuboctahedra, corners with five equivalent SnPr4Co8 cuboctahedra, faces with six equivalent SnPr4Co8 cuboctahedra, and faces with eight CoPr2Co7Sn3 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.39–2.57 Å. All Co–Sn bond lengths are 2.70 Å. In the third Co site, Co is bonded in a 12-coordinate geometry to four equivalent Pr, four Co, and four Sn atoms. The Co–Co bond length is 2.45 Å. There are a spread of Co–Sn bond distances ranging from 2.72–2.87 Å. In the fourth Co site, Co is bonded to nine Co and three equivalent Sn atoms to form CoCo9Sn3 cuboctahedra that share corners with three equivalent SnPr4Co8 cuboctahedra, faces with six equivalent SnPr4Co8 cuboctahedra, and faces with eight CoPr2Co7Sn3 cuboctahedra. All Co–Sn bond lengths are 2.71 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 10-coordinate geometry to six equivalent Pr and four Co atoms. In the second Sn site, Sn is bonded to four equivalent Pr and eight Co atoms to form distorted SnPr4Co8 cuboctahedra that share corners with four equivalent SnPr4Co8 cuboctahedra, corners with six CoPr2Co7Sn3 cuboctahedra, faces with eight CoPr2Co7Sn3 cuboctahedra, and faces with eight equivalent SnPr4Co8 cuboctahedra.