Double dielectric modification of nickel foam-based microwave absorbers with improved impedance matching and absorption performances

Proper physical property and well-designed microscopic structures are significant in determining the electromagnetic energy conversion. In this work, nickel foam (NiF)-based rod-like absorbers with double dielectric regulation were achieved via continuous hydrothermal reaction and subsequent heating treatment. The NiFbased uniform integration of binary metal oxides not only maintain the inherent excellent dielectric property of NiF, but also introduce extra dipolar polarizations (caused by multiple covered dielectrics) and Maxwell-WagnerSillars effect (induced by large dielectric property differences at the interfaces), which all contribute to the excellent microwave absorption performance. In addition, derived from the high/low dielectric synergetic effect, a balance between the introduction and dissipation of the electromagnetic energy can be realized. Based on that, the maximum bandwidth of NiF-based binary absorber reaches 7.28 GHz at 2.4 mm. This work not only provides a facile and versatile strategy to fabricate NiF-based ternary microwave absorbers, but also demonstrates the significant role of dielectric synergetic effect in optimizing microwave absorption performance.

Automated summary

The nickel foam-based rod-like absorbers with double dielectric regulation were achieved via continuous hydrothermal reaction and subsequent heating treatment. The introduction of extra dipolar polarizations and Maxwell-WagnerSillars effect contribute to the excellent microwave absorption performance, with a maximum bandwidth of 7.28 GHz.