DOE OSTI2020
Co2NbSn crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. there are two inequivalent Nb sites. In the first Nb site, Nb is bonded to eight Co and four Sn atoms to form distorted NbCo8Sn4 cuboctahedra that share corners with two equivalent NbCo8Sn4 cuboctahedra, corners with eight equivalent SnNb4Co8 cuboctahedra, edges with two equivalent NbCo8Sn4 cuboctahedra, faces with two equivalent NbCo8Sn4 cuboctahedra, and faces with six SnNb4Co8 cuboctahedra. There are four shorter (2.67 Å) and four longer (2.69 Å) Nb–Co bond lengths. There are two shorter (2.96 Å) and two longer (2.99 Å) Nb–Sn bond lengths. In the second Nb site, Nb is bonded in a 8-coordinate geometry to eight Co and four Sn atoms. There are a spread of Nb–Co bond distances ranging from 2.58–2.81 Å. There are two shorter (2.96 Å) and two longer (3.03 Å) Nb–Sn bond lengths. There are two inequivalent Co sites. In the first Co site, Co is bonded in a distorted body-centered cubic geometry to four Nb and four Sn atoms. There are two shorter (2.67 Å) and two longer (2.68 Å) Co–Sn bond lengths. In the second Co site, Co is bonded in a 8-coordinate geometry to four Nb and four Sn atoms. There are a spread of Co–Sn bond distances ranging from 2.62–2.74 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded to four Nb and eight Co atoms to form distorted SnNb4Co8 cuboctahedra that share corners with four equivalent SnNb4Co8 cuboctahedra, edges with eight SnNb4Co8 cuboctahedra, faces with four equivalent NbCo8Sn4 cuboctahedra, and faces with four equivalent SnNb4Co8 cuboctahedra. In the second Sn site, Sn is bonded to four Nb and eight Co atoms to form distorted SnNb4Co8 cuboctahedra that share corners with two equivalent SnNb4Co8 cuboctahedra, corners with eight equivalent NbCo8Sn4 cuboctahedra, edges with six SnNb4Co8 cuboctahedra, faces with two equivalent NbCo8Sn4 cuboctahedra, and faces with six SnNb4Co8 cuboctahedra.