Hydrothermal synthesis of NixCo10-x nanoalloys with an enhanced microwave absorption performance

Abstract

By using a facile hydrothermal synthesis, NiCo alloys with a particle size of 50–300 nm were prepared. The effects of the Ni:Co molar ratios on the microwave absorption properties in NiCo alloys were studied. The results showed that for Ni:Co molar ratios from 4:6 to 6:4, the morphology of the alloys changed from flower-like to nanoball-shaped. Specifically, the average size of Ni6Co4 was 84 nm, which showed a large specific surface area and produced increased interfacial polarization and multiple scattering. Ni6Co4 alloys exhibited excellent dielectric and magnetic properties, which enhanced microwave absorption properties. The optimum reflection loss in Ni6Co4 alloys was −53.29 dB at 9.44 GHz, and its thickness was 3.29 mm. The effective absorption bandwidth reached 6.64 GHz when the Ni6Co4 alloy thickness was 2.84 mm, which covered the C, Ku, and whole X bands. Additionally, the potential microwave dissipation mechanisms of as-fabricated NiCo alloys were illuminated, which were primarily derived from the optimized impedance matching, strengthened interfacial polarization, dipole polarization relaxation, and magnetic loss. These designs supply an effective way of obtaining promising candidate materials as high-efficient microwave absorbers.