FeNi alloys with controllable composition for tunable magnetic properties and broadband absorption

Abstract

For the further enhancement to the microwave absorbing capabilities of magnetic dendritic materials, this work has successfully prepared dendritic FexNi1-x (x = 0.5, 0.33, 0.25, 0.2) alloys through a facile electrodeposition method. FexNi1-x alloy composition can be easily tuned by changing iron ion concentration in the electrolyte. We investigate the effects of alloy composition on the crystal structure and morphology whereby we intrinsically analyzes the magnetic characteristics and microwave absorbing performance of FexNi1-x alloys. Particularly, Fe0.25Ni0.75 alloy demonstrates the strongest microwave absorption intensity, achieving the minimum reflection loss (RLmin) of −59.02 dB at 4.96 GHz. Comprehensively, Fe0.33Ni0.67 alloy (RLmin = −49.42 dB, d = 1.68 mm) attains optimal microwave absorption performance when combining the perspectives of absorber thickness, RLmin and effective bandwidth (RL<-20 dB). RL values of Fe0.33Ni0.67 alloy at the thickness of 1.4–2.5 mm, exceed −20 dB over a wide frequency range, covering almost the whole X and Ku band (8–18 GHz). Such exceptional microwave absorption performance is attributed to the unique dendritic structure which conduces to the multiple scattering of electromagnetic microwave, hence improving impedance matching and promoting energy dissipation. In addition, the practicability of FexNi1-x alloys is further confirmed by simulating the RCS value in the far field environment.