Tb2FeSi4 crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 13-coordinate geometry to two equivalent Fe(1), one Si(1), two equivalent Si(3), four equivalent Si(2), and four equivalent Si(4) atoms. In the second Tb site, Tb(2) is bonded in a 13-coordinate geometry to two equivalent Fe(1), one Si(2), two equivalent Si(4), four equivalent Si(1), and four equivalent Si(3) atoms. Fe(1) is bonded in a 8-coordinate geometry to two equivalent Tb(1), two equivalent Tb(2), two equivalent Si(1), and two equivalent Si(2) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Tb(1), four equivalent Tb(2), two equivalent Fe(1), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Tb(2), four equivalent Tb(1), two equivalent Fe(1), and one Si(4) atom. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Tb(1), four equivalent Tb(2), one Si(1), and two equivalent Si(4) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Tb(2), four equivalent Tb(1), one Si(2), and two equivalent Si(3) atoms.
Tb2FeSi4 crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 13-coordinate geometry to two equivalent Fe(1), one Si(1), two equivalent Si(3), four equivalent Si(2), and four equivalent Si(4) atoms. Both Tb(1)-Fe(1) bond lengths are 3.00 Å. The Tb(1)-Si(1) bond length is 3.13 Å. Both Tb(1)-Si(3) bond lengths are 3.07 Å. All Tb(1)-Si(2) bond lengths are 3.18 Å. All Tb(1)-Si(4) bond lengths are 3.06 Å. In the second Tb site, Tb(2) is bonded in a 13-coordinate geometry to two equivalent Fe(1), one Si(2), two equivalent Si(4), four equivalent Si(1), and four equivalent Si(3) atoms. Both Tb(2)-Fe(1) bond lengths are 3.02 Å. The Tb(2)-Si(2) bond length is 3.07 Å. Both Tb(2)-Si(4) bond lengths are 3.15 Å. All Tb(2)-Si(1) bond lengths are 3.16 Å. All Tb(2)-Si(3) bond lengths are 3.09 Å. Fe(1) is bonded in a 8-coordinate geometry to two equivalent Tb(1), two equivalent Tb(2), two equivalent Si(1), and two equivalent Si(2) atoms. Both Fe(1)-Si(1) bond lengths are 2.22 Å. Both Fe(1)-Si(2) bond lengths are 2.19 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Tb(1), four equivalent Tb(2), two equivalent Fe(1), and one Si(3) atom. The Si(1)-Si(3) bond length is 2.47 Å. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Tb(2), four equivalent Tb(1), two equivalent Fe(1), and one Si(4) atom. The Si(2)-Si(4) bond length is 2.44 Å. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to two equivalent Tb(1), four equivalent Tb(2), one Si(1), and two equivalent Si(4) atoms. Both Si(3)-Si(4) bond lengths are 2.39 Å. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Tb(2), four equivalent Tb(1), one Si(2), and two equivalent Si(3) atoms.