High-resolution dielectric spectroscopy and electric-field dependence of carbon allotropes including multiwall and single-wall nanotubes

High-resolution isothermal dielectric spectroscopy is reported as a function of frequency up to 10(5) Hz and electric field E-rot on four carbon allotropes; amorphous glass, diamond, multiwall nanotubes (MWNTs), and single-wall nanotubes (SWNTs). The diamond spectra are featureless while the glass, MWNT, and SWNT samples exhibit two modes. A common low-frequency mode, likely due to surface space charges, is observed at similar to 16 Hz that decreases in dispersion strength and increases in frequency linearly with increasing E-rot. A higher-frequency mode, different for each sample, is also observed having a dispersion strength and frequency independent of E-rot. (C) 2008 American Institute of Physics.