Layer‐by‐Layer Self‐Assembled Ferrite Multilayer Nanofilms for Microwave Absorption

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.