n this study, a series of Mg0.3Cu0.2Zn0.5Fe2-xLaxO4 ferrite nanoparticles with x= 0 to 0.15, with step 0.015 were synthesized by sol-gel auto combustion method. The effect of rare earth La which was substituted for Fe3+, on the structural, microstructure and magnetic properties of prepared samples were investigated. The structural characteristics of samples were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns showed the formation of cubic spinel structure for all samples without any extra peak. The microstructural evaluations showed homogeneous particles and also revealed that their size are about 36 – 51 nm. The magnetic properties of samples were investigated using vibration sample magnetometer (VSM) and Impedance analyzer. Results show that On La substitution, the values of saturation magnetization (MS) were slightly decreased. The real part of permeability as well as Curie temperature were dramatically decreased with increasing x.
