Mg23Sr6 crystallizes in the cubic Fm-3m space group. Sr(1) is bonded in a 12-coordinate geometry to four equivalent Mg(2), four equivalent Mg(3), and four equivalent Mg(4) atoms. There are four inequivalent Mg sites. In the first Mg site, Mg(4) is bonded in a distorted q6 geometry to three equivalent Sr(1), three equivalent Mg(2), three equivalent Mg(3), and three equivalent Mg(4) atoms. In the second Mg site, Mg(1) is bonded in a body-centered cubic geometry to eight equivalent Mg(3) atoms. In the third Mg site, Mg(2) is bonded to four equivalent Sr(1), four equivalent Mg(3), and four equivalent Mg(4) atoms to form a mixture of corner and face-sharing MgSr4Mg8 cuboctahedra. In the fourth Mg site, Mg(3) is bonded in a 10-coordinate geometry to three equivalent Sr(1), one Mg(1), three equivalent Mg(2), and three equivalent Mg(4) atoms.
Mg23Sr6 crystallizes in the cubic Fm-3m space group. Sr(1) is bonded in a 12-coordinate geometry to four equivalent Mg(2), four equivalent Mg(3), and four equivalent Mg(4) atoms. All Sr(1)-Mg(2) bond lengths are 3.77 Å. All Sr(1)-Mg(3) bond lengths are 3.61 Å. All Sr(1)-Mg(4) bond lengths are 3.70 Å. There are four inequivalent Mg sites. In the first Mg site, Mg(4) is bonded in a distorted q6 geometry to three equivalent Sr(1), three equivalent Mg(2), three equivalent Mg(3), and three equivalent Mg(4) atoms. All Mg(4)-Mg(2) bond lengths are 3.04 Å. All Mg(4)-Mg(3) bond lengths are 3.21 Å. All Mg(4)-Mg(4) bond lengths are 3.17 Å. In the second Mg site, Mg(1) is bonded in a body-centered cubic geometry to eight equivalent Mg(3) atoms. All Mg(1)-Mg(3) bond lengths are 3.15 Å. In the third Mg site, Mg(2) is bonded to four equivalent Sr(1), four equivalent Mg(3), and four equivalent Mg(4) atoms to form a mixture of corner and face-sharing MgSr4Mg8 cuboctahedra. All Mg(2)-Mg(3) bond lengths are 3.24 Å. In the fourth Mg site, Mg(3) is bonded in a 10-coordinate geometry to three equivalent Sr(1), one Mg(1), three equivalent Mg(2), and three equivalent Mg(4) atoms.