DOE OSTI2020
Mg4La23Ir7 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 equivalent Mg and nine La atoms to form face-sharing MgLa9Mg3 cuboctahedra. All Mg–Mg bond lengths are 3.20 Å. There are a spread of Mg–La bond distances ranging from 3.52–3.76 Å. In the second Mg site, Mg is bonded to three Mg and nine La atoms to form a mixture of face and corner-sharing MgLa9Mg3 cuboctahedra. Both Mg–Mg bond lengths are 3.24 Å. There are a spread of Mg–La bond distances ranging from 3.49–3.80 Å. There are nine inequivalent La sites. In the first La site, La is bonded in a distorted bent 150 degrees geometry to two Mg and two equivalent Ir atoms. Both La–Ir bond lengths are 2.93 Å. In the second La site, La is bonded in a distorted T-shaped geometry to three Ir atoms. There are two shorter (3.00 Å) and one longer (3.07 Å) La–Ir bond lengths. In the third La site, La is bonded in a bent 150 degrees geometry to two equivalent Mg and two Ir atoms. There are one shorter (2.89 Å) and one longer (2.94 Å) La–Ir bond lengths. In the fourth La site, La is bonded in a 3-coordinate geometry to three Mg and three Ir atoms. There are two shorter (2.94 Å) and one longer (2.97 Å) La–Ir bond lengths. In the fifth La site, La is bonded in a 3-coordinate geometry to one Mg and two equivalent Ir atoms. Both La–Ir bond lengths are 3.69 Å. In the sixth La site, La is bonded in a 3-coordinate geometry to three equivalent Ir atoms. All La–Ir bond lengths are 2.98 Å. In the seventh La site, La is bonded in a distorted water-like geometry to one Mg and four Ir atoms. There are two shorter (2.93 Å) and two longer (3.68 Å) La–Ir bond lengths. In the eighth La site, La is bonded in a 4-coordinate geometry to two equivalent Mg and two Ir atoms. There are one shorter (3.54 Å) and one longer (3.67 Å) La–Ir bond lengths. In the ninth La site, La is bonded in a 3-coordinate geometry to three equivalent Mg and three equivalent Ir atoms. All La–Ir bond lengths are 2.93 Å. There are three inequivalent Ir sites. In the first Ir site, Ir is bonded in a 6-coordinate geometry to nine La atoms. In the second Ir site, Ir is bonded in a 6-coordinate geometry to eight La atoms. In the third Ir site, Ir is bonded in a 6-coordinate geometry to nine La atoms.