Reduced graphene oxide wrapped SiO2 nanoparticles: AC and DC charge carrier dynamics

In the present work reduced graphene oxide wrapped SiO2 nanoparticles are prepared using a facile hydro- thermal technique. A detailed analysis of the charge transport mechanism in the prepared sample is carried out. The a.c. conductivity measurements are performed in the temperature range of 373-553 K. The d.c. conductivity measurements using four probe technique are performed in the temperature range of 15-300 K. At higher temperatures, thermally assisted nearest neighbor hopping is the dominant conduction mechanism. At temperatures below 300 K, variable range hopping can be observed with a crossover from Mott's to Efros-Shklovskii variable range hopping as temperature goes down below 100 K. Various relaxation processes arising due to different dielectric relaxation processes are discussed in detail using modified concurrent multiple Cole-Cole functions. Simultaneous fitting of real and imaginary parts of complex dielectric data is performed based on the proposed model, and a set of dielectric fit parameters as function temperature is obtained. These fit parameters are unique and fit remarkably well with the other representations of complex conductivity, resistivity, and electric modulus data at different temperatures.