Frequency Dependence of Atomic Deffusivity and Electrical Properties of Gum Arabic Graphite Composite

Abstract

In this study, samples of Gum Arabic (GA) with different amount of graphite (Gr) was prepared in order to study the effect of high frequency domain on the graphite electrical conductivity and atomic diffusivity of Gum Arabic (GA)/ graphite (Gr) composite. The FTIR peaks obtained were referred to the binding of Gr with the active groups in GA. Atomic diffusivity of Gr in GA was calculated using simple model and was found to varied randomly. This randomness might be due to the attachment of Gr with different active groups of GA. The addition of Gr results in improvement of the conductivity of GA to a far extend as it reaches the semiconductor range. The random variation in conductivities of the samples can be attributed to the effect of high frequency range, where the effect of phonon-electron is dominant. The samples subjected to the impedance spectroscopy (IS) for second and third time were acquired different diffusivities as well as conductivities. Such variations might indicate that IS was a processing technique similar to thermal treatment since it boosted the Gr atomic diffusion. We also adopted solid states reaction kinetic model to calculate diffusion Coefficient of graphite (Gr) in Gum Arabic (GA) as the function of temperatures and concentration D(t,c). From the calculations we found that the diffusion coefficient D increases with increasing temperature. At higher temperature the Gr atoms might get enough thermal energy to overcome the activation energy (Ea) banier and hence can easily be transported to a new atomic position. Such increase can be attributed to the large number of jumps or jump frequency which found to be directly proportion to the Gr concentration. Electric conductivity, calculated by Nemst-Einstein equation, at high concentration of Gr had exceeded that at lower concentration might be attributed to the effective of charges interactions, which lead to enhance the recombination of charge carriers.