High microwave absorption characteristic nanomaterial preparation and mechanism analysis

Abstract

Due to the excellent microwave absorption characteristics, YIG has a broad prospect in microwave application. This paper successfully synthesized YIG nanoparticles with the average size of 68.2 nm. The size uniformity of nanoparticles was verified and calculated by TEM and XRD. Microwave absorption value reached up to -34.5 dB, which was far more than microwave absorption threshold value (−10 dB). The mechanism of high microwave absorption characteristics discovered in the study is derived from four aspects: (a) Multiple scattering and interfacial polarization of YIG nanoparticles on surfaces. (b) High coercivity and high magnetic loss parameters of YIG nanoparticles in the high frequency region. (c) Magnetic loss mechanism and ferromagnetic resonance of YIG. (d) The influence of lesser pinning site caused by smaller grain size. The study found that the fundamental reasons of FMR spectrum asymmetric behavior come from three factors: (І) Nanoparticles random orientation. (П) Different easy axis. (Ш) Non-uniform resonance modes in the process of YIG synthesis. It was observed that microwave absorption markedly reduced due to the influence of skin effect and temperature. The effects of temperature on skin depth and microwave absorption are because of different amounts of excited electrons from the valence band and different magnetic spin configurations. The mechanism of the effect of temperature on the resistance of YIG was discovered, which is derived from electron hoping mechanism, remnant phases influence, the effect of the lattice atoms thermal vibration and skin effect.