Tunable wave absorption properties of β-MnO₂ nanorods and their application in dielectric composites

A new kind of β-MnO₂ nanorod (NR)–poly(vinylidene fluoride) (PVDF) functional composite with a high dielectric constant can be prepared by addition of β-MnO₂ NRs to PVDF. The microwave absorption properties of β-MnO₂ NRs, which were synthesized by a simple hydrothermal method on a large scale at low temperature, have been investigated for their applications in dielectric composites. It is found that the absorbers filled with β-MnO₂ NRs possess excellent microwave absorption properties, and the minimum reflection loss (RL) can be adjusted to different frequencies in the range 4–14 GHz by controlling the thickness of the β-MnO₂ NR–PVDF composite. The composite has a significantly high dielectric constant and good thermal stability, with quite a low percolation threshold. The dielectric constant can reach as high as 862 when the concentration of β-MnO₂ nanorod filler reaches 7 vol% at 10² Hz.