Reduction time effect on the dielectric characteristics of reduced-graphene-oxide--encapsulated barium titanate powder fillers

The reduction process for graphene oxide (GO) is important for this kind of graphene to be used as a conducting nanomaterial. After encapsulating barium titanate (BTO) powder particles in GO platelets, the GO-encapsulated BTO was chemically reduced with hydrazine (H₂NN(CH₃)₂) by varying the reduction time (6, 12, 18, and 24 h). Reduced-graphene-oxide--encapsulated BTO (RGO@BTO) fillers were mixed with a polymer matrix, to boost the performance of the dielectric composites with the help of interfacial polarization. All the composite samples with RGO@BTO fillers exhibited substantially higher dielectric constants (52–72%) due to encapsulation, while suppressing dielectric losses. The best dielectric performance was obtained from 18 h (the second longest time) not from 24 h. It can be interpreted that 18 h is a balancing point between the main process of removing oxygen-functional groups and the collateral process of attaching nitrogen-functional groups from a reduction agent of hydrazine. Detailed analyses of XRD, XPS, Raman scattering, and impedance analysis, support the specialty at 18 h. Additionally, AC-driven inorganic electroluminescence devices with RGO@BTO fillers yielded to the best performance at 18 h. Therefore, during the chemical reduction of RGO, optimizing the reduction time is imperative for high dielectric performance.