Materials Data on Sr5Al9 by Materials Project
Sr5Al9 is Bergman Structure: Mg32(Al,Zn)49 Bergman-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent Sr sites. In the first Sr site, Sr is bonded in a 6-coordinate geometry to six equivalent Al atoms. All Sr–Al bond lengths are 3.71 Å. In the second Sr site, Sr is bonded in a 1-coordinate geometry to ten Al atoms. There are a spread of Sr–Al bond distances ranging from 3.31–3.45 Å. In the third Sr site, Sr is bonded in a 12-coordinate geometry to twelve Al atoms. There are a spread of Sr–Al bond distances ranging from 3.37–3.44 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded to six equivalent Sr and six equivalent Al atoms to form edge-sharing AlSr6Al6 cuboctahedra. All Al–Al bond lengths are 2.92 Å. In the second Al site, Al is bonded in a 10-coordinate geometry to seven Sr and three equivalent Al atoms. All Al–Al bond lengths are 2.72 Å. In the third Al site, Al is bonded in a 11-coordinate geometry to five Sr and six Al atoms. There are two shorter (2.86 Å) and two longer (3.00 Å) Al–Al bond lengths.