Preparation and microwave absorbing properties of Fe₃O₄@lithium aluminum silicate glass ceramic/reduced graphene oxide composite

In order to improve the impedance matching of traditional magnetic absorbing materials and improve the electromagnetic wave absorption performance, the ternary composites, composed of magnetic material Fe₃O₄, a wave-transparent material lithium aluminum silicate glass-ceramic (LAS) and reduced graphene oxide (RGO), were prepared by three-step method. The structure, morphology and composition of the Fe₃O₄@LAS/RGO composites were characterized by various test methods, and the electromagnetic parameters and microwave absorbing properties were also analyzed. The effects of the addition amount of graphite oxide (GO) on the formation and microwave absorbing properties of the Fe₃O₄@LAS/RGO composites were investigated. As the amount of GO increases, the distribution of Fe₃O₄@LAS nanospheres becomes sparse, and the degree of stacking of RGO increases. When the mass fraction of GO is 40wt% (the molar ratio of Fe₃O₄/LAS is 1:0.2), the Fe₃O₄@LAS/RGO composite has the best microwave absorbing performance. The reflection loss reaches -65 dB at 12.4 GHz with a thickness of 2.1 mm and the absorption bandwidth with the reflection loss values less than -10 dB (more than 90% of electromagnetic waves are absorbed by materials) is up to 4 GHz at the corresponding thickness. The LAS, having wave-transparent properties, can introduce a multiple transmission-absorption mechanism into the Fe₃O₄@LAS/RGO composites.