DOE OSTI2020
Sc2NiGa8 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Sc is bonded to twelve Ga atoms to form ScGa12 cuboctahedra that share corners with eight equivalent ScGa12 cuboctahedra, edges with twelve GaSc4Ga8 cuboctahedra, faces with five equivalent ScGa12 cuboctahedra, and faces with eight GaSc4Ga8 cuboctahedra. There are a spread of Sc–Ga bond distances ranging from 2.88–2.96 Å. Ni is bonded in a body-centered cubic geometry to eight Ga atoms. All Ni–Ga bond lengths are 2.48 Å. There are seven inequivalent Ga sites. In the first Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Sc, two equivalent Ni, and seven Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.66–2.96 Å. In the second Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Sc, two equivalent Ni, and seven Ga atoms. Both Ga–Sc bond lengths are 2.88 Å. There are two shorter (2.83 Å) and four longer (2.96 Å) Ga–Ga bond lengths. In the third Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Sc, two equivalent Ni, and seven Ga atoms. There are one shorter (2.66 Å) and two longer (2.83 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Sc, two equivalent Ni, and seven Ga atoms. Both Ga–Sc bond lengths are 2.88 Å. Both Ga–Ga bond lengths are 2.83 Å. In the fifth Ga site, Ga is bonded to four equivalent Sc and eight Ga atoms to form distorted GaSc4Ga8 cuboctahedra that share corners with four equivalent GaSc4Ga8 cuboctahedra, edges with eight equivalent ScGa12 cuboctahedra, edges with eight equivalent GaSc4Ga8 cuboctahedra, faces with four equivalent ScGa12 cuboctahedra, and faces with twelve GaSc4Ga8 cuboctahedra. There are four shorter (2.95 Å) and four longer (2.96 Å) Ga–Ga bond lengths. In the sixth Ga site, Ga is bonded to four equivalent Sc and eight Ga atoms to form distorted GaSc4Ga8 cuboctahedra that share corners with four equivalent GaSc4Ga8 cuboctahedra, edges with eight equivalent ScGa12 cuboctahedra, edges with eight equivalent GaSc4Ga8 cuboctahedra, faces with four equivalent ScGa12 cuboctahedra, and faces with twelve GaSc4Ga8 cuboctahedra. All Ga–Ga bond lengths are 2.95 Å. In the seventh Ga site, Ga is bonded to four equivalent Sc and eight Ga atoms to form GaSc4Ga8 cuboctahedra that share corners with eight equivalent GaSc4Ga8 cuboctahedra, edges with four equivalent ScGa12 cuboctahedra, edges with eight GaSc4Ga8 cuboctahedra, faces with four equivalent ScGa12 cuboctahedra, and faces with nine GaSc4Ga8 cuboctahedra.