DOE OSTI2020
Li8EuSn7 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are five inequivalent Li sites. In the first Li site, Li is bonded in a 8-coordinate geometry to two equivalent Li, one Eu, and five Sn atoms. Both Li–Li bond lengths are 2.96 Å. The Li–Eu bond length is 3.21 Å. There are one shorter (2.78 Å) and four longer (2.97 Å) Li–Sn bond lengths. In the second Li site, Li is bonded to eight Li and four equivalent Sn atoms to form LiLi8Sn4 cuboctahedra that share corners with two equivalent LiLi8Sn4 cuboctahedra, edges with four equivalent SnLi8Eu2Sn2 cuboctahedra, faces with two equivalent LiLi8Sn4 cuboctahedra, and faces with four equivalent SnLi8Eu2Sn2 cuboctahedra. There are two shorter (2.93 Å) and four longer (2.98 Å) Li–Li bond lengths. All Li–Sn bond lengths are 3.22 Å. In the third Li site, Li is bonded in a 3-coordinate geometry to two equivalent Li, one Eu, and six Sn atoms. Both Li–Li bond lengths are 3.20 Å. The Li–Eu bond length is 3.27 Å. There are a spread of Li–Sn bond distances ranging from 2.86–3.30 Å. In the fourth Li site, Li is bonded in a 3-coordinate geometry to one Li, one Eu, and five Sn atoms. The Li–Eu bond length is 3.23 Å. There are a spread of Li–Sn bond distances ranging from 2.79–3.04 Å. In the fifth Li site, Li is bonded in a 4-coordinate geometry to two equivalent Li and five Sn atoms. There are a spread of Li–Sn bond distances ranging from 2.88–3.31 Å. Eu is bonded in a 7-coordinate geometry to five Li and ten Sn atoms. There are four shorter (3.39 Å) and six longer (3.44 Å) Eu–Sn bond lengths. There are five inequivalent Sn sites. In the first Sn site, Sn is bonded to eight Li, two equivalent Eu, and two Sn atoms to form distorted SnLi8Eu2Sn2 cuboctahedra that share corners with two equivalent SnLi8Eu2Sn2 cuboctahedra, edges with two equivalent LiLi8Sn4 cuboctahedra, edges with two equivalent SnLi8Eu2Sn2 cuboctahedra, faces with two equivalent LiLi8Sn4 cuboctahedra, and faces with four equivalent SnLi8Eu2Sn2 cuboctahedra. There are one shorter (2.96 Å) and one longer (2.99 Å) Sn–Sn bond lengths. In the second Sn site, Sn is bonded in a 4-coordinate geometry to four equivalent Li and two equivalent Eu atoms. In the third Sn site, Sn is bonded in a 7-coordinate geometry to seven Li and two equivalent Sn atoms. Both Sn–Sn bond lengths are 3.07 Å. In the fourth Sn site, Sn is bonded in a 6-coordinate geometry to four Li and four Sn atoms. Both Sn–Sn bond lengths are 3.44 Å. In the fifth Sn site, Sn is bonded in a 3-coordinate geometry to five Li, two equivalent Eu, and two Sn atoms.