Ba4Ga3Si20 crystallizes in the cubic Pm-3n space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 20-coordinate geometry to eight equivalent Si(2) and twelve equivalent Si(1) atoms. In the second Ba site, Ba(2) is bonded in a 20-coordinate geometry to four equivalent Ga(1), eight equivalent Si(1), and eight equivalent Si(2) atoms. Ga(1) is bonded to four equivalent Ba(2) and four equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing GaBa4Si4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(2) is bonded in a 5-coordinate geometry to one Ba(1), three equivalent Ba(2), one Si(2), and three equivalent Si(1) atoms. In the second Si site, Si(1) is bonded in a 7-coordinate geometry to one Ba(1), two equivalent Ba(2), one Ga(1), one Si(1), and two equivalent Si(2) atoms.
Ba4Ga3Si20 crystallizes in the cubic Pm-3n space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 20-coordinate geometry to eight equivalent Si(2) and twelve equivalent Si(1) atoms. All Ba(1)-Si(2) bond lengths are 3.36 Å. All Ba(1)-Si(1) bond lengths are 3.40 Å. In the second Ba site, Ba(2) is bonded in a 20-coordinate geometry to four equivalent Ga(1), eight equivalent Si(1), and eight equivalent Si(2) atoms. All Ba(2)-Ga(1) bond lengths are 3.71 Å. All Ba(2)-Si(1) bond lengths are 3.56 Å. All Ba(2)-Si(2) bond lengths are 3.89 Å. Ga(1) is bonded to four equivalent Ba(2) and four equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing GaBa4Si4 tetrahedra. All Ga(1)-Si(1) bond lengths are 2.49 Å. There are two inequivalent Si sites. In the first Si site, Si(2) is bonded in a 5-coordinate geometry to one Ba(1), three equivalent Ba(2), one Si(2), and three equivalent Si(1) atoms. The Si(2)-Si(2) bond length is 2.36 Å. All Si(2)-Si(1) bond lengths are 2.40 Å. In the second Si site, Si(1) is bonded in a 7-coordinate geometry to one Ba(1), two equivalent Ba(2), one Ga(1), one Si(1), and two equivalent Si(2) atoms. The Si(1)-Si(1) bond length is 2.48 Å.