Magnetic and microwave absorption properties of electrospun Co0.5Ni0.5Fe2O4 nanofibers

Co0.5Ni0.5Fe2O4 nanofibers with 70–100 nm in diameter were fabricated by the electrospinning and calcination process. Their saturation magnetization gradually enhances from 37.5 to 66.2 emu/g with increasing calcination temperature from 450 to 800 °C, while the corresponding coercivity increases initially, achieving a maximum value of 78.3 kA/m at 600 °C and then decreases with further increase in calcination temperature due to the transformation of magnetic structure from single-domain to multi-domain. By dispersing the nanofibers into a silicon rubber matrix homogeneously, the electromagnetic parameters of them were measured in the frequency range of 2–18 GHz and the microwave reflection loss was calculated according to the transmission line theory. The reflection loss exceeding −5 dB is obtained between 11 and 18 GHz for the silicon rubber composites containing 15 vol% Co0.5Ni0.5Fe2O4 nanofibers with coating thicknesses of 2.5–3.2 mm. These Co0.5Ni0.5Fe2O4 nanofibers possess a good microwave absorption performance in the Ku band and have a great potential as microwave absorber for practical applications.