Dielectric and magnetic properties of NiCuZn ferrite coated Sendust flakes through a sol-gel approach

Sendust flakes (with 9.59% Si, 5.88% Al and balanced Fe) were coated with NiCuZn ferrite nanoparticles by using a simple sol-gel approach. Both the coated and uncoated flakes were characterized by using scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. Composites made from the Sendust flakes with the in-plane alignment were fabricated via a vacuum infiltration method. Microwave measurement results indicated that permittivity of the composite made of the coated Sendust flakes was remarkably reduced, with a slight decrease in permeability over 0.1-8.55 GHz. Consequently, the sample with a thickness of 6 mm showed reflection loss exceeding -20 dB at 1.4 GHz, while reflection loss of the composite derived from the uncoated Sendust flakes could not reach -10 dB at the same sample thickness. Therefore, the Sendust flakes coated with NiCuZn ferrite nanoparticles could be promising candidates to develop microwave attenuation materials.