Dielectric response of multiwalled carbon nanotubes as a function of applied ac-electric fields

The complex dielectric constant (ε∗) is reported for multiwalled carbon nanotubes (MWCNTs) up to 105 Hz as a function of ac-electric field amplitudes Erot (in phase and same frequency as the measurement) and Eac (different phase and fixed frequency with respect to the measurement). A slow relaxation process (mode 1) is observed, which shifts to higher frequency with increasing Erot but is independent of Eac. A fast relaxation process (mode 2) is also observed, which is independent of Erot but shifts to higher frequency with increasing Eac (opposite to that of mode 1). An ac-conductivity analysis of MWCNT reveals insights on how Erot and Eac influence the dissipation.