Abstract
We demonstrate a simple method for fabricating multilayer thin films containing ferrite (Co0.5Zn0.5Fe2O4) nanoparticles, using layer-by-layer (LbL) self-assembly. These films have microwave absorbing properties for possible radar absorbing and stealth applications. To demonstrate incorporation of inorganic ferrite nanoparticles into an electrostatic-interaction-based LbL self-assembly, we fabricated two types of films: (1) a blended three-component LbL film consisting of a sequential poly(acrylic acid)/oleic acid-ferrite blend layer and a poly(allylamine hydrochloride) layer and (2) a tetralayer LbL film consisting of sequential poly(diallyldimethylammonium chloride), poly(sodium-4-sulfonate), bPEI-ferrite, and poly(sodium-4-sulfonate) layers. We compared surface morphologies, thicknesses, and packing density of the two types of ferrite multilayer film. Ferrite nanoparticles (Co0.5Zn0.5Fe2O4) were prepared via a coprecipitation method from an aqueous precursor solution. The structure and composition of the ferrite nanoparticles were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, and scanning electron microscopy. X-ray diffraction patterns of ferrite nanoparticles indicated a cubic spinel structure, and energy dispersive X-ray spectroscopy revealed their composition. Thickness growth and surface morphology were measured using a profilometer, atomic force microscope, and scanning electron microscope.
Highlights
Microwave absorbing materials, commonly known as radar absorbing materials, are in high demand for microwave absorption coatings on the surface of military stealth aircraft to avoid detection by enemy radar
During electrostatic interaction-based LbL assembly, the structure and morphology of fabricated multilayer thin film can be affected by parameters such as pH, adsorption time, and concentration of solute and salt
We focused on incorporating ferrite nanoparticles into a multilayer nanofilm
Summary
Commonly known as radar absorbing materials, are in high demand for microwave absorption coatings on the surface of military stealth aircraft to avoid detection by enemy radar. The unique microwave absorbing properties of ferrite nanoparticles, resulting from both magnetic and dielectric losses, have been explored by many groups [9,10,11,12,13,14,15]. Spinel ferrite has large resistivity and large magnetic loss; it has been used for microwave absorbing materials. Zhao group doped cobalt and cupper ions with Ni-Zn spinel ferrite to tune the microwave absorbing properties. The microwave absorbing region, in which reflection loss values are lesser than −10 bB, of NiCoZnFe2O4 is achieved at 3.9–11.5 GHz. The control of microwave absorption of metallic ion doped Ni-Zn ferrites mainly results from magnetic loss change derive from metallic ions [16]
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