Fabrication and enhanced dielectric constant of nanocomposite films based on polyimide and core–shell structured Al2O3@0.4mol%Nb-(Ba0.87Sr0.04Ca0.09)(Ti0.86Zr0.08Sn0.06)O3 nanoparticles

A series of nanocomposite films loaded with various concentrations of fillers were successfully synthesized by solution casting method (BSCTZS nanoparticles (NPs) as filler and polyimide (PI) as polymer matrix). To improve the dispersion and the physical–chemical properties of (Ba 0.87 Sr 0.04 Ca 0.09 )(Ti 0.86 Zr 0.08 Sn 0.06 )O 3 (BSCTZS) NPs surface, BSCTZS NPs were modified by Al 2 O 3 coating and modified Al 2 O 3 @Nb-BSCTZS NPs/PI nanocomposite films were prepared. The prepared modified Al 2 O 3 @Nb-BSCTZS NPs were characterized by X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM), and the dielectric properties of these composites were characterized in details. As a result, the nanocomposite films filled with 5 vol% Al 2 O 3 @0.4mol%Nb-BSCTZS nanoparticles exhibit an excellent energy density of 2.11 J cm −3 at 298 kV/mm, which is 48% over the original pristine PI (1.42 J cm −3 at 313 kV/mm). This work can provide a prospective solution for the preparation of composite film materials with high dielectric constant and high energy density.