科研之友
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摘要
To create a spinel ferrite with excellent performance for electromagnetic (EM) wave absorption in the low fre-quency range of 4-6 GHz, compositions based on Co0.75Zn0.125Fe0.125Fe2O4 (CZF-1) and Co0.5Zn0.25Fe0.25Fe2O4 (CZF-2) with multiple elements substituted for A sites were synthesized by using solvothermal method. Hollow porous magnetic/magnetic heterostructure microspheres (HHMs) of CZF-A1 and CZF-A2 with multiple in-terfaces were prepared by hydrogen-thermal reduction of CZF-1 and CZF-2, and their unique structure and EM absorption properties were investigated in detail. The widest effective absorption bandwidth (EAB) of CZF-A1 and CZF-A2 was 4.1 GHz (13.6-17.7 GHz) and 3.7 GHz (8.0-11.7 GHz) for a corresponding thickness of 1.4 mm and 2.0 mm, respectively. In addition, the minimum reflection loss (R.Lmin) of CZF-A1 and CZF-A2 reached - 49.1 dB (at fm = 13.4 GHz) and -45.0 dB (at fm = 4.2 GHz) at a thicknesses of 1.6 mm and 3.7 mm, respectively. More specifically, in the low frequency region of 4-6 GHz, CZF-A1 and CZF-A2 exhibited excellent EM wave absorption due to the effective regulation of their natural resonance frequency. The EM wave absorption fre-quency band of CZF-A1 and CZF-A2 samples was able to completely cover the 4-6 GHz frequency region for at coating thickness of CZF-A1 and CZF-A2 was only 3.5 mm and 3.3 mm respectively, and their R.Lmin reached - 36.5 dB and -22.6 dB. Moreover, the absorption mechanisms of CZF-A1 and CZF-A2 including magnetic resonance, eddy current loss, interfacial polarization and dipole polarization were also investigated in detail. This research provides new insights and guidance for the development of spinel ferrite-based EM absorbers for high efficiency EM wave absorption in the low frequency (4-6 GHz) region.
