Electrical conductivity studies and correlated barrier hopping transport in Europium-doped graphene oxide nanocomposites

Abstract

Graphene oxide was prepared using the modified Hammers method. Europium nitrate of varying concentrations was added to obtain different composites. The morphology of doped samples was analyzed by atomic force microscopy. The folded-sheet-like pattern on the surface is an evidence of the rolling of graphene layers. X-ray diffraction patterns for doped samples were obtained, which show polycrystalline nature; the structure remains unchanged after doping with europium. Optical studies, including UV-visible spectrum analysis, reveal that europium-doped graphene oxide possesses an extremely wide band gap energy. Graphene oxide and the doped samples were subjected to thermal conductivity analysis. Arrhenius plot directly gives the activation energy in the intrinsic and extrinsic regions due to the presence of rare-earth impurity, such as europium ions, along with the graphene oxide. Hopping level conduction in doped samples was analyzed using the correlated barrier hopping model, and different hopping conduction parameters were thereby identified.