Ba3Si23 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 24-coordinate geometry to four Si(1,1,1); eight Si(2,2); and twelve Si(3,3,3,3,3) atoms. In the second Ba site, Ba(1) is bonded in a 24-coordinate geometry to four equivalent Si(1); eight equivalent Si(2); and twelve Si(3,3) atoms. There are ten inequivalent Si sites. In the first Si site, Si(3) is bonded in a 6-coordinate geometry to three equivalent Ba(1), one Si(1), one Si(3), and two equivalent Si(2) atoms. In the second Si site, Si(1) is bonded to four Ba(1,1) and four Si(3,3,3) atoms to form distorted SiBa4Si4 tetrahedra that share corners with six Si(1,1)Ba4Si4 tetrahedra; corners with sixteen Si(2,2)Ba3Si4 tetrahedra; edges with two equivalent Si(1)Ba4Si4 tetrahedra; and faces with eight Si(2,2)Ba3Si4 tetrahedra. In the third Si site, Si(1) is bonded to four equivalent Ba(1) and four equivalent Si(3) atoms to form distorted SiBa4Si4 tetrahedra that share corners with eight equivalent Si(1)Ba4Si4 tetrahedra, corners with sixteen equivalent Si(2)Ba3Si4 tetrahedra, and faces with eight equivalent Si(2)Ba3Si4 tetrahedra. In the fourth Si site, Si(1) is bonded in a distorted body-centered cubic geometry to four equivalent Ba(1) and four equivalent Si(3) atoms. In the fifth Si site, Si(2) is bonded to three Ba(1,1); one Si(2); and three Si(3,3,3) atoms to form SiBa3Si4 tetrahedra that share corners with four equivalent Si(1)Ba4Si4 tetrahedra; corners with fifteen Si(2,2)Ba3Si4 tetrahedra; edges with three Si(2,2)Ba3Si4 tetrahedra;  a faceface with one Si(2)Ba3Si4 tetrahedra; and faces with three Si(1,1)Ba4Si4 tetrahedra. In the sixth Si site, Si(2) is bonded to three Ba(1,1); one Si(2); and three Si(3,3,3) atoms to form SiBa3Si4 tetrahedra that share corners with six Si(1,1)Ba4Si4 tetrahedra; corners with fifteen Si(2,2)Ba3Si4 tetrahedra; edges with three Si(2,2)Ba3Si4 tetrahedra;  a faceface with one Si(2)Ba3Si4 tetrahedra; and faces with two equivalent Si(1)Ba4Si4 tetrahedra. In the seventh Si site, Si(3) is bonded in a 6-coordinate geometry to three equivalent Ba(1), one Si(1), one Si(3), and two equivalent Si(2) atoms. In the eighth Si site, Si(3) is bonded in a 6-coordinate geometry to three Ba(1,1); one Si(1); one Si(3); and two equivalent Si(2) atoms. In the ninth Si site, Si(3) is bonded in a 6-coordinate geometry to three Ba(1,1); one Si(1); one Si(3); and two equivalent Si(2) atoms. In the tenth Si site, Si(3) is bonded in a 6-coordinate geometry to three Ba(1,1); one Si(1); one Si(3); and two Si(2,2) atoms.
Ba3Si23 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 24-coordinate geometry to four Si(1,1,1); eight Si(2,2); and twelve Si(3,3,3,3,3) atoms. All Ba(1)-Si(1,1,1) bond lengths are 3.65 Å. All Ba(1)-Si(2,2) bond lengths are 3.83 Å. There are eight shorter (3.50 Å) and four longer (3.95 Å) Ba(1)-Si(3,3,3,3,3) bond lengths. In the second Ba site, Ba(1) is bonded in a 24-coordinate geometry to four equivalent Si(1); eight equivalent Si(2); and twelve Si(3,3) atoms. All Ba(1)-Si(1) bond lengths are 3.65 Å. All Ba(1)-Si(2) bond lengths are 3.83 Å. There are eight shorter (3.50 Å) and four longer (3.95 Å) Ba(1)-Si(3,3) bond lengths. There are ten inequivalent Si sites. In the first Si site, Si(3) is bonded in a 6-coordinate geometry to three equivalent Ba(1), one Si(1), one Si(3), and two equivalent Si(2) atoms. The Si(3)-Si(1) bond length is 2.42 Å. The Si(3)-Si(3) bond length is 2.49 Å. Both Si(3)-Si(2) bond lengths are 2.36 Å. In the second Si site, Si(1) is bonded to four Ba(1,1) and four Si(3,3,3) atoms to form distorted SiBa4Si4 tetrahedra that share corners with six Si(1,1)Ba4Si4 tetrahedra; corners with sixteen Si(2,2)Ba3Si4 tetrahedra; edges with two equivalent Si(1)Ba4Si4 tetrahedra; and faces with eight Si(2,2)Ba3Si4 tetrahedra. All Si(1)-Si(3,3,3) bond lengths are 2.42 Å. In the third Si site, Si(1) is bonded to four equivalent Ba(1) and four equivalent Si(3) atoms to form distorted SiBa4Si4 tetrahedra that share corners with eight equivalent Si(1)Ba4Si4 tetrahedra, corners with sixteen equivalent Si(2)Ba3Si4 tetrahedra, and faces with eight equivalent Si(2)Ba3Si4 tetrahedra. All Si(1)-Si(3) bond lengths are 2.42 Å. In the fourth Si site, Si(1) is bonded in a distorted body-centered cubic geometry to four equivalent Ba(1) and four equivalent Si(3) atoms. In the fifth Si site, Si(2) is bonded to three Ba(1,1); one Si(2); and three Si(3,3,3) atoms to form SiBa3Si4 tetrahedra that share corners with four equivalent Si(1)Ba4Si4 tetrahedra; corners with fifteen Si(2,2)Ba3Si4 tetrahedra; edges with three Si(2,2)Ba3Si4 tetrahedra;  a faceface with one Si(2)Ba3Si4 tetrahedra; and faces with three Si(1,1)Ba4Si4 tetrahedra. The Si(2)-Si(2) bond length is 2.35 Å. All Si(2)-Si(3,3,3) bond lengths are 2.36 Å. In the sixth Si site, Si(2) is bonded to three Ba(1,1); one Si(2); and three Si(3,3,3) atoms to form SiBa3Si4 tetrahedra that share corners with six Si(1,1)Ba4Si4 tetrahedra; corners with fifteen Si(2,2)Ba3Si4 tetrahedra; edges with three Si(2,2)Ba3Si4 tetrahedra;  a faceface with one Si(2)Ba3Si4 tetrahedra; and faces with two equivalent Si(1)Ba4Si4 tetrahedra. The Si(2)-Ba(1) bond length is 3.83 Å. The Si(2)-Si(2) bond length is 2.35 Å. Both Si(2)-Si(3,3) bond lengths are 2.36 Å. In the seventh Si site, Si(3) is bonded in a 6-coordinate geometry to three equivalent Ba(1), one Si(1), one Si(3), and two equivalent Si(2) atoms. In the eighth Si site, Si(3) is bonded in a 6-coordinate geometry to three Ba(1,1); one Si(1); one Si(3); and two equivalent Si(2) atoms. The Si(3)-Ba(1) bond length is 3.95 Å. The Si(3)-Si(3) bond length is 2.49 Å. In the ninth Si site, Si(3) is bonded in a 6-coordinate geometry to three Ba(1,1); one Si(1); one Si(3); and two equivalent Si(2) atoms. The Si(3)-Si(3) bond length is 2.49 Å. In the tenth Si site, Si(3) is bonded in a 6-coordinate geometry to three Ba(1,1); one Si(1); one Si(3); and two Si(2,2) atoms. The Si(3)-Si(3) bond length is 2.49 Å.