Effect of Zn and Ir doping on microwave absorption of SrFe12-2xZnxIrxO19

Abstract

With a high anisotropic field, the M-type SrFe12O19 is not considered as a microwave absorber in the frequency range of 0.1–18 GHz. Zn and Ir codoping decreases the anisotropic field greatly. The magnetic resonance frequency falls in the range of 4 GHz − 5.3 GHz in SrFe12-2xZnxIrxO19. Both the permeabilities and the permittivities increase with the increasing Zn and Ir doping as × ≤ 0.5, and decrease in × = 0.7. The different behavior is due to the impurity in × = 0.7. The high permittivity in × = 0.5 are due to the leakage conduction as deduced from the Cole-Cole semicircles, and so is it partly in × = 0.7 as well. Debye relaxations take function in × = 0.1, 0.3 and also 0.7. The impedance matching and the attenuation factor have the best values in × = 0.5. As a result, the × = 0.5 sample has a very good microwave absorbing property with the single-layer bandwidth (RL < −10 dB) as broad as 12.1 GHz at the thickness of 2.1 mm. If the thickness varies from 1.3 mm to 9.5 mm, the bandwidth with RL < −10 dB covers the full frequency range of 1.5–18 GHz. Compared with the advanced materials reported, SrFe12-2xZnxIrxO19 is very competitive as both single-layer and multi-layer absorber. The quarter-wavelength criteria explains the relationship between the optimum thickness and the frequency.