Microwave absorption properties of Ni-substituted cobalt ferrite-loaded carbon nanofiber composites

The NixCo1-xFe2O4 (x = 0, 0.25, 0.5, 0.75)/CNFs composites were synthesized in situ by solvothermal method. A series of characterizations of the prepared samples includes X-ray diffraction (XRD), scanning microscope (SEM), vibrating sample magnetometer (VSM) and a vector network analyzer (VNA). XRD and SEM results indicated that the particles have good crystallinity and no other impurities. With the increase of Ni ion doping, the average particle size of the sample gradually decreased, smaller microspheres were beneficial to the bonding of CNFs and Ni0.5Co0.5Fe2O4 particles, and CNFs formed a good encapsulation structure. Combined with the VSM analysis, the change of Ni2+ content results in an increase in the value of Ms, while the values of Mr and Hc decreased slightly, and its magnetic properties were optimized. The complex permittivity and permeability of the NixCo1-xFe2O4/CNFs composites at a frequency of 1-18 GHz were tested by VNA, and the reflection loss (RL) was calculated. The results illustrated that when the Ni2+ doping amount is 50 %, Ni0.5Co0.5Fe2O4/CNFs particles have considerable absorbing performance, the minimum reflection loss reached - 42.24 dB at 14.68 GHz, the effective absorbing frequency band was 4 GHz (12.39-16.40 GHz), and the corresponding matching layer thickness was only 1.5 mm. Therefore, Ni0.5Co0.5Fe2O4/CNFs particles could be used as a thin layer of strong absorbing material.

Automated summary

NixCo1-xFe2O4/CNFs composites were synthesized in situ by solvothermal method and characterized. The Ni0.5Co0.5Fe2O4/CNFs particles with 50% Ni2+ doping showed excellent absorbing performance and could be used as a thin layer of strong absorbing material.