DOE OSTI2020
MgEr4Rh crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg is bonded to three equivalent Mg and nine Er atoms to form a mixture of corner and face-sharing MgEr9Mg3 cuboctahedra. All Mg–Mg bond lengths are 3.06 Å. There are a spread of Mg–Er bond distances ranging from 3.30–3.53 Å. There are three inequivalent Er sites. In the first Er site, Er is bonded in a 3-coordinate geometry to three equivalent Mg, three equivalent Er, and three equivalent Rh atoms. All Er–Er bond lengths are 3.51 Å. All Er–Rh bond lengths are 2.80 Å. In the second Er site, Er is bonded in a bent 150 degrees geometry to two equivalent Mg, four equivalent Er, and two equivalent Rh atoms. All Er–Er bond lengths are 3.62 Å. Both Er–Rh bond lengths are 2.80 Å. In the third Er site, Er is bonded in a 4-coordinate geometry to two equivalent Mg, ten Er, and two equivalent Rh atoms. All Er–Er bond lengths are 3.58 Å. Both Er–Rh bond lengths are 3.50 Å. Rh is bonded in a 6-coordinate geometry to nine Er atoms.