Geometrical influence of conducting fillers on the dielectric tunable properties of antiferroelectric ceramic/conducting filler/polystyrene composites under low electric field

(Pb_0.87Ba_0.1La_0.02)(Zr_0.7Sn_0.24Ti_0.06)O₃ (PBLZST) antiferroelectric ceramic/conducting filler (carbon nanopowder, graphene nanosheets or carbon nanotubes)/polystyrene (PS) composites were prepared by solution-mixing method and molded by hot-pressing process. All composites exhibited high room-temperature tunability under low electric field (200 V/mm) due to the introduction of conducting filler, which increased the effective electric field applied on the ceramics particles. For different carbon conducting fillers, their shapes are different and thus they have different specific surface areas, resulting in different mass ratios for obtaining highest dielectric tunability. The maximum room-temperature dielectric tunability of three-phase composites with different conducting fillers were respectively 17.5% (1.0 wt% carbon nanopowder), 17% (0.4 wt% carbon nanotubes) and 20% (0.6 wt% graphene nanosheets) at 200 V/mm, which were two or three times of the tunability of PBLZST/PS composites without any conducting fillers. Besides, all composites showed low dielectric loss and permittivity that met the practical application requirements. All these make three-phase composites obtained in this work promising candidates for tunable devices application.