Observation of the microwave near-field enhancement effect in suspensions comprising single-walled carbon nanotubes

The strong polarization of isolated finite-length single-walled carbon nanotubes (CNTs) or bundles of CNTs has been predicted to lead to a strong near field enhancement effect that provokes additional electromagnetic energy dissipation in a conductive host (Shuba et al 2010 J. Appl. Phys. 108 114302). Here, we theoretically and experimentally show that this effect can be observed in the microwave frequency range via measurements of the spectra of the effective permittivity of CNT-based suspensions. Microwave effective permittivity of the suspensions comprising both annealed and doped CNTs has been measured in the temperature range from 300 to 330 K. The experimental data gives evidence of the unique properties of CNTs-to enhance electromagnetic fields in a volume as much as 100 times larger than the volume occupied by the nanotube itself.