Low frequency dielectric response mechanism of bamboo charcoal

The carbonization of bamboo at 400 °C–700 °C resulted in the formation of graphite crystals embedded in amorphous carbon. The high dielectric constants (≈103 at 1 Hz) of these carbon materials were attributed to the presence of polar groups such as -OH, -NH2 and -COOH with marginal contribution from interfacial polarization. The dielectric constants were observed to be frequency-dependent and found to be decreased with increasing frequency. The measured dielectric loss was also found to be decreasing with increasing frequency. Conductance dominant dielectric loss observed in 400 °C–600 °C annealed samples was further supported by the Cole-Cole plot. Maxwell–Wagner–Sillars interfacial polarization relaxation along with conduction loss was observed only for the 700 °C annealed sample.