DOE OSTI2020
Mg16Al12F crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are ten inequivalent Mg sites. In the first Mg site, Mg is bonded in a single-bond geometry to two equivalent Mg, four Al, and one F atom. Both Mg–Mg bond lengths are 3.02 Å. There are two shorter (2.92 Å) and two longer (2.96 Å) Mg–Al bond lengths. The Mg–F bond length is 2.05 Å. In the second Mg site, Mg is bonded in a 7-coordinate geometry to three Mg and twelve Al atoms. There are one shorter (3.15 Å) and two longer (3.23 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.05–3.38 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 3.07–3.11 Å. There are a spread of Mg–Al bond distances ranging from 2.92–3.21 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. Both Mg–Mg bond lengths are 2.98 Å. There are four shorter (3.02 Å) and two longer (3.20 Å) Mg–Al bond lengths. In the fifth Mg site, Mg is bonded in a single-bond geometry to five Mg, four Al, and one F atom. There are a spread of Mg–Mg bond distances ranging from 3.11–3.26 Å. There are a spread of Mg–Al bond distances ranging from 2.92–3.09 Å. The Mg–F bond length is 2.15 Å. In the sixth Mg site, Mg is bonded in a 4-coordinate geometry to five Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.10–3.32 Å. There are a spread of Mg–Al bond distances ranging from 2.96–3.15 Å. In the seventh Mg site, Mg is bonded in a 1-coordinate geometry to six Mg and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.10–3.21 Å. There are a spread of Mg–Al bond distances ranging from 2.85–3.14 Å. In the eighth Mg site, Mg is bonded in a 10-coordinate geometry to four Mg and six Al atoms. There are one shorter (3.01 Å) and one longer (3.05 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.00–3.19 Å. In the ninth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. The Mg–Mg bond length is 3.09 Å. There are a spread of Mg–Al bond distances ranging from 2.90–3.10 Å. In the tenth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. There are a spread of Mg–Al bond distances ranging from 2.99–3.13 Å. There are seven inequivalent Al sites. In the first Al site, Al is bonded in a distorted single-bond geometry to five Mg, three Al, and one F atom. There are two shorter (2.69 Å) and one longer (2.72 Å) Al–Al bond lengths. The Al–F bond length is 2.46 Å. 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 2.77 Å. In the third Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are one shorter (2.70 Å) and one longer (2.79 Å) Al–Al bond lengths. In the fourth Al site, Al is bonded in a 10-coordinate geometry to seven Mg and three Al atoms. There are one shorter (2.68 Å) and one longer (2.81 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded in a 10-coordinate geometry to seven Mg and three Al atoms. There are one shorter (2.74 Å) and one longer (2.76 Å) Al–Al bond lengths. In the sixth Al site, Al is bonded in a 10-coordinate geometry to eight Mg and three Al atoms. The Al–Al bond length is 2.72 Å. In the seventh Al site, Al is bonded in a 10-coordinate geometry to seven Mg and three Al atoms. The Al–Al bond length is 2.79 Å. F is bonded in a 3-coordinate geometry to three Mg and one Al atom.