Magnetic and Reflection Loss Characteristics of SrFe $_{12 - {\rm x}}$ (Sm $_{0.5}$ Dy

Samarium-Dysprosium substituted strontium ferrite nanoparticles with composition of SrFe_12-xDy_x/2Sm_x/2O₁₉(x = 0-2.5 in a step of x = 0.5) were synthesized and then deposited on the outer surface of multiwalled carbon nanotubes (MWCNTs) by a sol-gel method. The volume percentage of carbon nanotubes in nanocomposites was 10%. The structural characteristics of ferrite-MWCNTs were studied by x-ray diffraction, scanning electron microscopy and transmission electron microscopy. It was found that almost single phase strontium ferrite nanoparticles with narrow size distribution were successfully deposited on MWCNTs. Magnetic susceptibility measurement confirmed that the dynamic magnetic behaviour of samples was described by a Vogel-Fulcher law. SQUID results reflect that with an increase in substitution contents the coercivity and saturation of magnetization decrease. The reflection loss measurements were carried out on substituted ferrite nanoparticles with and without addition of MWCNTs. The obtained results revealed that the incorporation of MWCNTs can enhance reflection loss and bandwidth in Ku band.