▎ 摘　　要

Reduced graphene oxide (rGO) platelets are used to encapsulate barium titanate (BaTiO3, BTO) powder particles by functionalizing rGO and BTO, which is mixed with a polymer to become a dielectric composite. The polymer composite film exhibits improved dielectric characteristics-a dielectric constant of 219 (75% higher than that of the pure BTO film) mainly due to numerous micro-capacitors, composed of BTO as a dielectric medium and rGO as electrodes, in the polymer. The increase of the dielectric loss, a typical unwanted phenomenon by inclusion of conducting nanomaterials, is successfully suppressed below 7% (from 0.045 to 0.048). This is achieved by virtually removing free rGO platelets within the polymer matrix during the encapsulation process, impeding percolative connection between free rGO platelets. Only graphene encapsulation would facilitate both BTO-based micro-capacitors and the deprivation of free rGO, which would simultaneously yield to a high dielectric constant and a low dielectric loss. Thus, encapsulation, one way of elaborate mixing methods, is essential for high-performance dielectrics, which can be applied to other composite materials with ease.