Study On Microwave Absorbing Properties Of High Entropy Spinel Type Ferrites

Electronic and communication devices provide basic guarantee for modern daily life,which may cause electromagnetic pollution in addition to bring the convenience.Thus,microwave absorbing materials such as ferrites have attracted extensive attention.However,the lack of dielectric loss mechanism is the main challenge that limits their application.To cope this challenge,the design and preparation of high-entropy spinel-type ferrite ceramics and the regulation of microwave absorption properties are studied in this paper.The main research contents are as follows:Three high-entropy spinel-type ferrite ceramics including(Mg0.2Fe0.2Co0.2Ni0.2Cu0.2)Fe2O4,(Mg0.2Fe0.2Co0.2Ni0.2Zn0.2)Fe2O4 and(Mg0.2Fe0.2Co0.2Ni0.2Mn0.2)Fe2O4,which were designed with the goal of enhancing the dielectric properties,improving the whole band resistance matching characteristic and strengthening electro-magnetic loss coupling performance are successfully synthesized by solid state synthesis.The results show that all three high-entropy spinel-type ferrite samples have achieved the design goal,the high entropy structure and composition design realizes the coupling effect of dielectric loss and magnetic loss,which can effectively enhance the microwave absorption performance of the material.The enhanced dielectric properties are attributed to nanodomain,hopping mechanism of resonance effect and high-entropy effect;while the good magnetic loss ability is due to the presence of magnetic components natural resonance,natural exchange resonance and eddy loss.Three high-entropy spinel-type ferrite ceramics with different mass fractions all shown good electromagnetic wave absorption ability.For(Mg0.2Fe0.2Co0.2Ni0.2Cu0.2)Fe2O4,the minimum reflection loss(RLmin)of 70 wt% sample reaches-26.11 d B,and the largest optimized effective absorption bandwidth(EAB)reaches 6.12 GHz;the RLmin of 80 wt% sample reaches-33.5 d B,and the largest EAB reaches 6.8 GHz.For(Mg0.2Fe0.2Co0.2Ni0.2Zn0.2)Fe2O4,the RLmin of 70 wt% sample is-27.4 d B the maximum EAB is 6.46 GHz;the RLmin of 80 wt% sample is-35.85 d B the maximum EAB is 6.8GHz.For(Mg0.2Fe0.2Co0.2Ni0.2Mn0.2)Fe2O4,the RLminof70 wt% sample reaches-35.10 d B,and the optimized EAB is 7.48 GHz;the RLmin of 80 wt% sample is-38.34 d B the maximum EAB is 3.74 GHz.Their effective absorption peaks are highly coincident with the natural resonance peak,which indicate that high-entropy spinel-type ferrite ceramics are a new type of microwave absorbing material with dielectric enhancement,coupling electromagnetic loss and dominated by magnetic loss.Considering the convenient manufacture of high-entropy spinel-type ferrite ceramics as well as their low density,low cost and adjustable electromagnetic properties,the current research suggests them as powerful player for thin and wide-band EM wave absorbing materials.