Comparative Study of Structure, FMR and Magnetic Properties of Nanocomposite and Mixture Ferrite.

This investigation presents design of 20% M-type BaFe12O19 hexaferrite as a core coated by 80% MgFe2O4 spinel ferrite as a shell (〖Mg〗_80-H_20) in addition to, a mixture of 80% MgFe2O4 spinel ferrite and 20% M-type BaFe12O19 hexa-ferrite powders. The spinel and nanocompsite ferrite materials were synthesized by the wet mechano-chemical co-precipitation route and all prepared samples; spinel, nanocomposite and mixture are annealed at 1200 oC for 6 hours. The results of X-ray diffraction patterns, High Resolution Transmission electron microscope (HRTEM) images and Fourier-transform infrared spectroscopy (FT-IR) revealed the formation of two different composite materials. Comparing the FMR behavior of the nanocomposite and the mixed materials, the resonance field H_r of nanocomposite is lower than that of the mixture. This may be attributed to the effect of spring exchange coupling in the nanocomposite sample. The hysteresis loop of the 〖Mg〗_80-H_20 nanocomposite structure is similar to that of cubic spinel ferrite and exhibits the same Ms (18 emu/g) despite of its different values of Mr and Hc. Enhancing the remnant magnetization for the 〖Mg〗_80-H_20 nanocomposite and mixed materials is mainly attributed to the overcoming of magnetic exchange interaction and high magneto-crystalline anisotropy of hard phase in competition with dipolar interaction of soft phase. Comparing the FMR behavior of the nanocomposite and the mixed materials, the resonance field H_r of nanocomposite is lower than that of the mixture. This may be attributed to the effect of spring exchange coupling in the nanocomposite sample.