Ba3Si4 crystallizes in the tetragonal P4_2/mnm space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to four equivalent Si(1) and four equivalent Si(2) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to four equivalent Si(1) and four equivalent Si(2) atoms. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to four equivalent Si(1) and four equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), two equivalent Ba(3), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), two equivalent Ba(3), one Si(2), and two equivalent Si(1) atoms.
Ba3Si4 crystallizes in the tetragonal P4_2/mnm space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to four equivalent Si(1) and four equivalent Si(2) atoms. All Ba(1)-Si(1) bond lengths are 3.35 Å. All Ba(1)-Si(2) bond lengths are 3.57 Å. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to four equivalent Si(1) and four equivalent Si(2) atoms. There are two shorter (3.30 Å) and two longer (3.66 Å) Ba(2)-Si(1) bond lengths. All Ba(2)-Si(2) bond lengths are 3.39 Å. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to four equivalent Si(1) and four equivalent Si(2) atoms. All Ba(3)-Si(1) bond lengths are 3.60 Å. There are two shorter (3.73 Å) and two longer (3.79 Å) Ba(3)-Si(2) bond lengths. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), two equivalent Ba(3), and two equivalent Si(2) atoms. Both Si(1)-Si(2) bond lengths are 2.42 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Ba(1), two equivalent Ba(2), two equivalent Ba(3), one Si(2), and two equivalent Si(1) atoms. The Si(2)-Si(2) bond length is 2.39 Å.