Preparation and dielectric property of SiO₂ surface coating modified BaTiO₃/polyimide composite film

Polyimide (PI) was chosen as the matrix of the composite, barium titanate/polyimide (BaTiO₃/PI) nanocomposite films were prepared with in situ polymerization. In order to improve the dispersion and the physical-chemical properties of BT surface, barium titanate was modified by SiO₂ coating and modified barium titanate/polyimide (BaTiO₃/PI) nanocomposite films were prepared. The prepared modified BaTiO₃ was characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), and the dielectric properties of the composites were characterized in detail. It was shown that surface modification with SiO₂ was the physical effect and there were no new substances forming. When BaTiO₃ was modified by 5% SiO₂, the dielectric constant of the composite film was 21.8 (10³ Hz), the loss tangent 0.00521, breakdown strength 76 MV/m, energy storage density 0.56 J/cm³. The BaTiO₃ surface coating modification by SiO₂ was beneficial to the dielectric properties of the BaTiO₃/PI composite film.