Synthesis of core-shell ZnFe2O4@SiO2 hollow microspheres/reduced graphene oxides for a high-performance EM wave absorber

Abstract

The core-shell ZnFe2O4@SiO2 hollow microspheres/reduced graphene oxides (RGO-ZnFe2O4@SiO2) composites were successfully synthesized by a rational process. SEM and TEM results illustrate that the ZnFe2O4@SiO2 hollow microspheres are of core-shell structure with an average diameter of about 1µm mixed with graphene sheets. Compared with ZnFe2O4@SiO2 hollow microspheres and RGO-ZnFe2O4 composites, the as-prepared RGO-ZnFe2O4@SiO2 composites exhibit excellent electromagnetic (EM) wave absorption properties in terms of both the maximum reflection loss and the absorption bandwidth. The maximum reflection loss of RGO-ZnFe2O4@SiO2 composites is −45.8dB at 7.6GHz with the thickness of 3.7mm and the absorption bandwidth with the reflection loss below −10dB is up to 14.5GHz (from 3.5 to 18.0GHz) with a thickness in the range of 2.0–6.0mm. It may also be stressed that the developed composites cover the whole X band (8.0–12.0GHz), which could be used for military radars and direct broadcast satellites (DBS).