Multiscale assembly of Fe2B porous microspheres for large magnetic losses in the gigahertz range

A large magnetic loss is an important factor for microwave absorbers. In this study, we used a molten salt method to synthesize a multiscale assembly of Fe2B porous microspheres comprising microparticles assembled by Fe2B nanoflakes. The magnetic loss factor values are larger than those of the dielectric loss factor at 2-18 GHz, which is ascribed to the shape anisotropy and multiple magnetic resonances. The Landau-Lifshitz-Gilbert equations are used to explain the origin of the multiple magnetic resonances, and the fitting curves match well with the permeability values. For 1.8 mm and 1.9 mm thick absorber layers, the effective absorption band, in which the absolute value of the reflection loss exceeds 10 dB, can reach 4.4 GHz, covering 13.6-18 GHz and 12.8-17.2 GHz, respectively. Our study opens up a new way to improve the magnetic loss ability of absorbers with artificial architectures. (C) 2018 Published by Elsevier B.V.