Magnetic structure of the La3NiGe2-type Tb3NiGe2 and Mn5Si3-type Tb5NixGe3−x (x=0 and 0.3)

► Below∼135 K Tb3NiGe2 exhibits a commensurate b-collinear ferrimagnetic ordering. ► Below ≥89 K Tb5Ni0.3Ge2.7 demonstrates flat spiral antiferromagnetic ordering. ► At∼10 K the magnetic unit cell of Tb5Ni0.3Ge2.7 decreases down to a×a×5c.