Microwave Complex Permittivity and Absorption of MnO₂Nanorods and Nanoparticles

Abstract

The electromagnetic and microwave-absorbing properties of irregular-shaped MnO2 nanoparticles (NP) and MnO2 nanorods (NR) as dielectric absorbent fillers in an insulating epoxy resin were investigated by the transmission/reflection method at 2−18 GHz. The real part of complex permittivity ϵ′ for 60 wt% of MnO2 NP-epoxy composite fluctuated within the range of 7.8−9.6 while the corresponding ϵ′ for 12 wt% of MnO2 NR-epoxy absorber was 6.6−10.0. The dielectric loss tangent of MnO2 NR-epoxy absorber is relatively larger than that of MnO2 NP-epoxy composite. The minimum reflection loss reaches −11.6 dB at 9.12 GHz for 60 wt% MnO2 NP-epoxy absorber and −20.7 dB at 9.6 GHz for 12 wt% MnO2 NR-epoxy absorber with 3 mm thickness.