Geometrical shape adjustment of KTa_0.5Nb_0.5O₃ nanofillers for tailored dielectric properties of KTa_0.5Nb_0.5O₃/PVDF composite

This paper indicates that rational design and precise control for the structure and shape of nanofillers are effective for achieving the desired permittivity and breakdown strength for high energy densities of polymer nanocomposites. Two types of KTa_0.5Nb_0.5O₃ (KTN) nanoparticles with different shapes (NC-KTN and NR-KTN) were introduced into the PVDF matrix. The molecular dynamic simulation and the Brunauer-Emmett-Teller (BET) surface area proved that the nonbonding interaction energy is stronger in the NR-KTN/PVDF composite films due to the larger surface area of NR-KTN (30.96 m² g^-1). In addition, the interfacial polarization related to the shape of nanofillers further improved the dielectric permittivity of NR-KTN/PVDF composite films. Through the comparison between the experimental data and various theoretical models, we concluded that the geometric shape of fillers has a significant impact on the dielectric constant of composite films.