Spinel Cu0.5Zn0.5Fe2O4 ferrite doped with different rare earth ions is investigated. FT-IR was used to investigate
the effect of different rare earth substitution on the magnetic properties of this system. It was found that
when Fe3+ is replaced with La and Nd ions, almost no changes were observed in the band position of IR spectra.
As Gd and Dy substituted, small shifts for the band spectra were detected. On the other hand when Sm is
replacing Fe3+ a noticed increase in the frequency band position was observed. The observed increase in the
band ν1 position for Sm substitution can be explained as the replace of Fe3+ ions with Sm3+ ions in the tetrahedral
site (A-site) of the spinel.