Ba4Si23 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(1) and twelve equivalent Si(2) atoms. In the second Ba site, Ba(2) is bonded in a 20-coordinate geometry to four equivalent Si(3), eight equivalent Si(1), and eight equivalent Si(2) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 5-coordinate geometry to one Ba(1), three equivalent Ba(2), one Si(1), and three equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Ba(1), two equivalent Ba(2), one Si(2), one Si(3), and two equivalent Si(1) atoms. In the third Si site, Si(3) is bonded to four equivalent Ba(2) and four equivalent Si(2) atoms to form a mixture of distorted corner and edge-sharing SiBa4Si4 tetrahedra.
Ba4Si23 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(1) and twelve equivalent Si(2) atoms. All Ba(1)-Si(1) bond lengths are 3.33 Å. All Ba(1)-Si(2) bond lengths are 3.43 Å. In the second Ba site, Ba(2) is bonded in a 20-coordinate geometry to four equivalent Si(3), eight equivalent Si(1), and eight equivalent Si(2) atoms. All Ba(2)-Si(3) bond lengths are 3.68 Å. All Ba(2)-Si(1) bond lengths are 3.86 Å. All Ba(2)-Si(2) bond lengths are 3.52 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 5-coordinate geometry to one Ba(1), three equivalent Ba(2), one Si(1), and three equivalent Si(2) atoms. The Si(1)-Si(1) bond length is 2.34 Å. All Si(1)-Si(2) bond lengths are 2.40 Å. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Ba(1), two equivalent Ba(2), one Si(2), one Si(3), and two equivalent Si(1) atoms. The Si(2)-Si(2) bond length is 2.51 Å. The Si(2)-Si(3) bond length is 2.42 Å. In the third Si site, Si(3) is bonded to four equivalent Ba(2) and four equivalent Si(2) atoms to form a mixture of distorted corner and edge-sharing SiBa4Si4 tetrahedra.