DOE OSTI2020
Mg4La23Rh7 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to three Mg and nine La atoms to form a mixture of corner and face-sharing MgLa9Mg3 cuboctahedra. There are one shorter (3.20 Å) and two longer (3.25 Å) Mg–Mg bond lengths. There are a spread of Mg–La bond distances ranging from 3.49–3.77 Å. In the second Mg site, Mg is bonded to three equivalent Mg and nine La atoms to form face-sharing MgLa9Mg3 cuboctahedra. There are a spread of Mg–La bond distances ranging from 3.52–3.75 Å. There are nine inequivalent La sites. In the first La site, La is bonded in a bent 150 degrees geometry to two equivalent Mg and two Rh atoms. There are one shorter (2.87 Å) and one longer (2.94 Å) La–Rh bond lengths. In the second La site, La is bonded in a distorted water-like geometry to one Mg and four Rh atoms. There are two shorter (2.92 Å) and two longer (3.72 Å) La–Rh bond lengths. In the third La site, La is bonded in a 3-coordinate geometry to one Mg and two equivalent Rh atoms. Both La–Rh bond lengths are 3.69 Å. In the fourth La site, La is bonded in a 4-coordinate geometry to two equivalent Mg and two Rh atoms. There are one shorter (3.51 Å) and one longer (3.69 Å) La–Rh bond lengths. In the fifth La site, La is bonded in a 3-coordinate geometry to three Rh atoms. There are two shorter (3.02 Å) and one longer (3.10 Å) La–Rh bond lengths. In the sixth La site, La is bonded in a 3-coordinate geometry to three Mg and three Rh atoms. There are two shorter (2.94 Å) and one longer (2.98 Å) La–Rh bond lengths. In the seventh La site, La is bonded in a distorted bent 150 degrees geometry to two Mg and two equivalent Rh atoms. Both La–Rh bond lengths are 2.93 Å. In the eighth La site, La is bonded in a 3-coordinate geometry to three equivalent Rh atoms. All La–Rh bond lengths are 3.01 Å. In the ninth La site, La is bonded in a 3-coordinate geometry to three equivalent Mg and three equivalent Rh atoms. All La–Rh bond lengths are 2.94 Å. There are three inequivalent Rh sites. In the first Rh site, Rh is bonded in a 6-coordinate geometry to nine La atoms. In the second Rh site, Rh is bonded in a 6-coordinate geometry to eight La atoms. In the third Rh site, Rh is bonded in a 6-coordinate geometry to nine La atoms.