Microwave Complex Permittivity and Absorption of MnO₂ Nanorods 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.

Keywords:

• Microwave absorber
• manganese dioxide nanowire
• complex permittivity

Acknowledgments

This work was supported by the National Science Council of Taiwan under NSC-100-2221-E-035-044. The authors would like to thank Prof. C. K. Lin at Taipei Medical University for tecnical support in sample preparation.