High-entropy spinel ferrites MFe2O4 (M = Mg, Mn, Fe, Co, Ni, Cu, Zn) with tunable electromagnetic properties and strong microwave absorption

Abstract

Abstract Ferrites are the most widely used microwave absorbing materials to deal with the threat of electromagnetic (EM) pollution. However, the lack of sufficient dielectric loss capacity is the main challenge that limits their applications. To cope with this challenge, three high-entropy (HE) spinel-type ferrite ceramics including (Mg0.2Mn0.2Fe0.2Co0.2Ni0.2)Fe2O4, (Mg0.2Fe0.2Co0.2Ni0.2Cu0.2)Fe2O4, and (Mg0.2Fe0.2Co0.2Ni0.2Zn0.2)Fe2O4 were designed and successfully prepared through solid state synthesis. The results show that all three HE MFe2O4 samples exhibit synergetic dielectric loss and magnetic loss. The good magnetic loss ability is due to the presence of magnetic components; while the enhanced dielectric properties are attributed to nano-domain, hopping mechanism of resonance effect and HE effect. Among three HE spinels, (Mg0.2Mn0.2Fe0.2Co0.2Ni0.2)Fe2O4 shows the best EM wave absorption performance, e.g., its minimum reflection loss (RLmin) reaches −35.10 dB at 6.78 GHz with a thickness of 3.5 mm, and the optimized effective absorption bandwidth (EAB) is 7.48 GHz from 8.48 to 15.96 GHz at the thickness of 2.4 mm. Due to the easy preparation and strong EM dissipation ability, HE MFe2O4 are promising as a new type of EM absorption materials.

Keywords

• high-entropy ceramics (HECs)
• spinel-type ferrite
• electromagnetic (EM) wave absorption
• dielectric loss
• magnetic loss