Enhanced microwave absorption performance of geopolymer composites by incorporating hollow Fe3O4 nanospheres

Abstract

AbstractHollow Fe3O4 nanospheres (h‐Fe3O4) with tunable sizes were synthesized and proposed as fillers to prepare microwave absorbing geopolymer (GP) composites. We studied the effect of different sizes of h‐Fe3O4 on microwave absorption (MA). The MA performance was enhanced as the size of h‐Fe3O4 in GP decreased. Furthermore, the GP composites containing h‐Fe3O4 achieved better MA capability than their counterparts containing solid Fe3O4 nanospheres (s‐Fe3O4) of the same size. The GP composites with a small size of h‐Fe3O4 exhibited the best minimum reflection loss (RLmin) of −39.3 dB at 14.0 GHz and an effective absorption bandwidth (EAB) of 4.8 GHz at 2.2 mm. The outstanding MA capability, possibly as a result of improved dielectric loss and magnetic loss together with well‐matched impedance, demonstrated that GP composites are competitive construction materials when MA is critical. The radar cross section (RCS) simulation was conducted to assess the MA performance of composite materials in practical environments.