Structural, Magnetic and Microwave Properties of Eu-doped Barium Hexaferrite Powders

Abstract

Eu-doped M-type barium ferrite powders (Ba1−x Eu x Fe12O19) with x=0.0, 0.1, 0.2 and 0.25 were prepared by sol-gel method. The synthesized samples are characterized by thermo gravimetric analysis (TG-DTA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and vector network analyzer. All the synthesized samples have the nearly single-magnetoplumbite phase. The results show that the crystallite size of doped samples is smaller than pure one. The saturation magnetization of doped ferrites decreases by the increase in Eu doping, while the coercivity increases. Maximum coercivity achieved in this study is 6.12 KOe for x=0.25 sample. The enhancement of coercivity by Eu doping is mainly due to the higher magnetocrystalline anisotropy, which is attributed to the partial change of Fe+3 ion to Fe+2 ion. The maximum reflection loss (RL) of −43 dB at frequency range of 12–18 GHz for the x=0.1 sample was obtained. The increase in reflection loss at higher frequency suggests that the Eu-doped sample can be used for the application in microwave devices.