Electrical Conductivity and Dielectrical Properties of Bulk Methylene Green

Thermal stability, direct current electrical conductivity (σ DC), alternating current electrical conductivity (σ AC) and dielectric properties of bulk methylene green (MG) have been investigated. The thermal stability of MG was studied by differential scanning calorimetry and thermogravimetry techniques. Temperature dependence of σ DC showed that the MG has semiconductor behavior with two activation energies determined as 0.12 eV and 0.31 eV in the temperature range 303–343 K and 363–463 K, respectively. The σ AC of bulk MG was performed in the frequency range 150 Hz–5 MHz and temperature range 303–463 K. The dependence of AC conductivity on frequency for MG is found to satisfy Jonscher’s\ universal power law, especially at high frequencies. The correlated barrier hopping model is found to be applicable in which the density of localized states is determined. The σ AC is thermally activated and the activation energy decreases with the increases in frequency. The variation of the real and imaginary parts of the dielectric constant with the frequency and temperature is explained.