DOE OSTI2019
Mg16MnAl12 crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are five inequivalent Mg sites. In the first Mg site, Mg is bonded in a 1-coordinate geometry to three equivalent Mg, one Mn, and twelve Al atoms. All Mg–Mg bond lengths are 3.12 Å. The Mg–Mn bond length is 2.79 Å. There are three shorter (3.14 Å) and nine longer (3.20 Å) Mg–Al bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. There are one shorter (3.02 Å) and two longer (3.03 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.08–3.15 Å. In the third Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.04–3.12 Å. There are a spread of Mg–Al bond distances ranging from 2.95–3.14 Å. In the fourth Mg site, Mg is bonded in a 12-coordinate geometry to six Mg, one Mn, and five Al atoms. There are two shorter (3.16 Å) and two longer (3.26 Å) Mg–Mg bond lengths. The Mg–Mn bond length is 3.07 Å. There are a spread of Mg–Al bond distances ranging from 2.95–3.14 Å. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. Both Mg–Mg bond lengths are 3.23 Å. There are a spread of Mg–Al bond distances ranging from 2.90–3.14 Å. Mn is bonded in a 10-coordinate geometry to four Mg and six equivalent Al atoms. All Mn–Al bond lengths are 2.84 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a distorted q6 geometry to eight Mg and three Al atoms. There are one shorter (2.69 Å) and two longer (2.77 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. Both Al–Al bond lengths are 2.79 Å. In the third Al site, Al is bonded in a 11-coordinate geometry to seven Mg, one Mn, and three Al atoms. Both Al–Al bond lengths are 2.65 Å.