Tb2Al3Ge4 crystallizes in the orthorhombic Cmce space group. Tb(1) is bonded in a 8-coordinate geometry to four equivalent Ge(1) and four equivalent Ge(2) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Ge(2) and four equivalent Ge(1) atoms to form distorted corner-sharing AlGe6 octahedra. The corner-sharing octahedral tilt angles are 31°. In the second Al site, Al(2) is bonded in a 5-coordinate geometry to one Ge(1) and four equivalent Ge(2) atoms. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a 7-coordinate geometry to four equivalent Tb(1), one Al(2), and two equivalent Al(1) atoms. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to four equivalent Tb(1), one Al(1), and four equivalent Al(2) atoms.
Tb2Al3Ge4 crystallizes in the orthorhombic Cmce space group. Tb(1) is bonded in a 8-coordinate geometry to four equivalent Ge(1) and four equivalent Ge(2) atoms. There are two shorter (3.12 Å) and two longer (3.19 Å) Tb(1)-Ge(1) bond lengths. There are a spread of Tb(1)-Ge(2) bond distances ranging from 3.09-3.20 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent Ge(2) and four equivalent Ge(1) atoms to form distorted corner-sharing AlGe6 octahedra. The corner-sharing octahedral tilt angles are 31°. Both Al(1)-Ge(2) bond lengths are 2.77 Å. All Al(1)-Ge(1) bond lengths are 2.58 Å. In the second Al site, Al(2) is bonded in a 5-coordinate geometry to one Ge(1) and four equivalent Ge(2) atoms. The Al(2)-Ge(1) bond length is 2.53 Å. There are two shorter (2.62 Å) and two longer (2.86 Å) Al(2)-Ge(2) bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a 7-coordinate geometry to four equivalent Tb(1), one Al(2), and two equivalent Al(1) atoms. In the second Ge site, Ge(2) is bonded in a 9-coordinate geometry to four equivalent Tb(1), one Al(1), and four equivalent Al(2) atoms.