Urchin-like ni microspherical structure with enhanced magnetic loss for thin microwave absorber at gigahertz

We describe in this report a wet chemical reduction synthetic strategy for synthesizing urchin-like Ni microspherical structures, in which the nanowires self-assembled by Ni nanoparticles with the size of 5-20nm are assembled in a radial form from the center to the surface of the spherical oriented arrays. Urchin-like Ni microspherical structures exhibit the strong magnetic natural resonance peak at 7.0GHz and superior magnetic loss at 2-18GHz, originated from relatively high anisotropy energy of urchin-like shape. Electromagnetic absorption measurements show that the urchin-like Ni microspherical structures possess outstanding microwave absorption performance at 2-18GHz. An optimal reflection loss of -21.98dB can be observed at 17.4GHz with a matching thickness of 1.4mm and the effective absorption (below -10 dB, 90% absorption) bandwidth is 5 GHz (12-17 GHz) with a thickness of 1.7mm. The excellent microwave absorption performance may be attributed to the good impedance, large attenuation constant and novel magnetic loss ability.