DOE OSTI2020
Sm2Fe15Ga2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded in a 1-coordinate geometry to seventeen Fe and two equivalent Ga atoms. There are a spread of Sm–Fe bond distances ranging from 3.01–3.41 Å. Both Sm–Ga bond lengths are 3.14 Å. In the second Sm site, Sm is bonded in a 10-coordinate geometry to fifteen Fe and four equivalent Ga atoms. There are a spread of Sm–Fe bond distances ranging from 3.06–3.36 Å. There are two shorter (3.20 Å) and two longer (3.26 Å) Sm–Ga bond lengths. There are ten inequivalent Fe sites. In the first Fe site, Fe is bonded in a 2-coordinate geometry to one Sm and thirteen Fe atoms. There are a spread of Fe–Fe bond distances ranging from 2.39–2.76 Å. In the second Fe site, Fe is bonded in a 2-coordinate geometry to one Sm, eleven Fe, and two equivalent Ga atoms. There are a spread of Fe–Fe bond distances ranging from 2.61–2.77 Å. Both Fe–Ga bond lengths are 2.68 Å. In the third Fe site, Fe is bonded to two Sm, nine Fe, and one Ga atom to form distorted FeSm2GaFe9 cuboctahedra that share corners with three equivalent GaSm3Fe9 cuboctahedra, corners with twenty-one FeSm2GaFe9 cuboctahedra, an edgeedge with one GaSm3Fe9 cuboctahedra, edges with four FeSm2Ga2Fe8 cuboctahedra, faces with three equivalent GaSm3Fe9 cuboctahedra, and faces with eighteen FeSm2GaFe9 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.43–2.66 Å. The Fe–Ga bond length is 2.66 Å. In the fourth Fe site, Fe is bonded to two Sm, nine Fe, and one Ga atom to form distorted FeSm2GaFe9 cuboctahedra that share corners with three equivalent GaSm3Fe9 cuboctahedra, corners with twenty-one FeSm2GaFe9 cuboctahedra, an edgeedge with one GaSm3Fe9 cuboctahedra, edges with four FeSm2GaFe9 cuboctahedra, faces with three equivalent GaSm3Fe9 cuboctahedra, and faces with eighteen FeSm2GaFe9 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.45–2.64 Å. The Fe–Ga bond length is 2.59 Å. In the fifth Fe site, Fe is bonded to two Sm, eight Fe, and two equivalent Ga atoms to form distorted FeSm2Ga2Fe8 cuboctahedra that share corners with two equivalent GaSm3Fe9 cuboctahedra, corners with twenty-two FeSm2GaFe9 cuboctahedra, edges with five FeSm2GaFe9 cuboctahedra, faces with four equivalent GaSm3Fe9 cuboctahedra, and faces with seventeen FeSm2GaFe9 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.43–2.72 Å. There are one shorter (2.59 Å) and one longer (2.64 Å) Fe–Ga bond lengths. In the sixth Fe site, Fe is bonded to two Sm, nine Fe, and one Ga atom to form distorted FeSm2GaFe9 cuboctahedra that share corners with four equivalent GaSm3Fe9 cuboctahedra, corners with eighteen FeSm2GaFe9 cuboctahedra, edges with two equivalent GaSm3Fe9 cuboctahedra, edges with eight FeSm2GaFe9 cuboctahedra, faces with two equivalent GaSm3Fe9 cuboctahedra, and faces with sixteen FeSm2GaFe9 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.43–2.46 Å. The Fe–Ga bond length is 2.50 Å. In the seventh Fe site, Fe is bonded to two Sm, eight Fe, and two equivalent Ga atoms to form distorted FeSm2Ga2Fe8 cuboctahedra that share corners with two equivalent GaSm3Fe9 cuboctahedra, corners with twenty FeSm2GaFe9 cuboctahedra, edges with two equivalent GaSm3Fe9 cuboctahedra, edges with eight FeSm2GaFe9 cuboctahedra, faces with two equivalent GaSm3Fe9 cuboctahedra, and faces with sixteen FeSm2GaFe9 cuboctahedra. Both Fe–Fe bond lengths are 2.46 Å. Both Fe–Ga bond lengths are 2.48 Å. In the eighth Fe site, Fe is bonded to three Sm and nine Fe atoms to form FeSm3Fe9 cuboctahedra that share corners with twenty-three FeSm2GaFe9 cuboctahedra, edges with four equivalent GaSm3Fe9 cuboctahedra, edges with six FeSm2Ga2Fe8 cuboctahedra, faces with four equivalent GaSm3Fe9 cuboctahedra, and faces with sixteen FeSm2GaFe9 cuboctahedra. Both Fe–Fe bond lengths are 2.48 Å. In the ninth Fe site, Fe is bonded to three Sm, eight Fe, and one Ga atom to form FeSm3GaFe8 cuboctahedra that share corners with five equivalent GaSm3Fe9 cuboctahedra, corners with eighteen FeSm2GaFe9 cuboctahedra, an edgeedge with one GaSm3Fe9 cuboctahedra, edges with nine FeSm2GaFe9 cuboctahedra, faces with two equivalent GaSm3Fe9 cuboctahedra, and faces with eighteen FeSm2GaFe9 cuboctahedra. The Fe–Ga bond length is 2.55 Å. In the tenth Fe site, Fe is bonded to three Sm, seven Fe, and two equivalent Ga atoms to form distorted FeSm3Ga2Fe7 cuboctahedra that share corners with six equivalent GaSm3Fe9 cuboctahedra, corners with seventeen FeSm2GaFe9 cuboctahedra, edges with ten FeSm2GaFe9 cuboctahedra, faces with two equivalent GaSm3Fe9 cuboctahedra, and faces with eighteen FeSm2GaFe9 cuboctahedra. Both Fe–Ga bond lengths are 2.54 Å. Ga is bonded to three Sm and nine Fe atoms to form GaSm3Fe9 cuboctahedra that share corners with two equivalent GaSm3Fe9 cuboctahedra, corners with twenty-one FeSm2GaFe9 cuboctahedra, edges with two equivalent GaSm3Fe9 cuboctahedra, edges with eight FeSm2GaFe9 cuboctahedra, faces with two equivalent GaSm3Fe9 cuboctahedra, and faces with eighteen FeSm2GaFe9 cuboctahedra.