Rare Earth Doping (La+3 and Sm+3) Effects on the Magnetic Properties of Ferrite Cobaltite for C and X- band applications

FeCo ₂ O ₄ and FeRE _0.01 Co ₂ O ₄ (RE = Sm, La) spinel ferrites were synthesized via the sol-gel method and systematically studied for their structural, morphological, and magnetic properties. XRD analysis confirmed the formation of single-phase spinel structures. La³⁺ doping resulted in lattice expansion and improved crystallinity, whereas Sm ^+ 3 doping induced lattice contraction. FESEM micrographs revealed spherical-like particles with a significant reduction in grain size upon doping, decreasing from \(\:\sim\:\)229 nm in the undoped sample to around 115 nm for FeSm _0.01 Co _1.99 O ₄ and 89 nm for FeLa _0.01 Co _1.99 O ₄ ferrite powders. Notably, La ^+ 3 substitution led to a more uniform particle distribution and reduced agglomeration. FTIR spectroscopy further confirmed the spinel ferrite structure and no impurity-related bands. VSM curves showed soft ferromagnetic behavior in all samples, with distinct magnetic responses upon rare-earth doping. La³⁺doping significantly enhanced the saturation magnetization (\(\:{M}_{s}=48.64\:emu/g)\), coercivity (\(\:{H}_{c}=216.84\:Oe)\), anisotropy (\(\:K=10285.82\:J/{m}^{3})\), and a high microwave frequency \(\:(\omega\:=10.74\:GHz\)). In contrast, Sm ⁺³ doping caused a significant reduction in these parameters, likely due to the disruption of superexchange interactions and increased spin disorder. Overall, La-doped FeCo ₂ O ₄ sample showed strong potential for C and X-band applications, essential for radar and communication systems.