Design of double-layer absorbers based on Co2Y@C core-shell nanofibers and carbon nanofibers for high-efficient and tunable microwave absorption

A novel double-layer microwave absorber based on Ba2Co2Fe12O22@C core-shell nanofibers (Co2Y@C NFs) and carbon nanofibers (CNFs) was designed, and their microwave absorption properties were systematically inves-tigated in the frequency range of 2-18 GHz. Benefiting from the better impedance matching characteristic of the matching layer (50 wt% Co2Y@C NFs/paraffin composite) and the stronger dielectric loss ability of the absorbing layer (5 wt% CNFs/paraffin composite), the optimized double-layer absorbers exhibit stronger absorption and wider effective absorption bandwidth compared to the corresponding single-layer absorbers. When the thick-nesses of the absorbing and matching layer are respectively 0.62 mm and 1.38 mm (total thickness of 2 mm), the optimal reflection loss (RL) reaches-46.9 dB at 16.8 GHz, and the effective absorption bandwidth (EAB) is 4.1 GHz (from 13.9 to 18 GHz). Meanwhile, when the thicknesses of the absorbing and matching layer are 1.03 and 1.98 mm (total thickness of 3.01 mm), respectively, the optimal RL is up to-63.7 dB at 10.0 GHz with an EAB of 9.5 GHz ranging from 8.5 to 18 GHz. The absorption intensity and range of the double-layer absorber can be easily adjusted by regulating the thickness of the absorber, which shows good potential for practical applications.