Dielectric constant and energy density of poly(vinylidene fluoride) nanocomposites filled with core-shell structured BaTiO3@Al2O3 nanoparticles

Ceramics-polymer nanocomposites consisting of core-shell structured BaTiO3@Al2O3 (BT@Al2O3) nanoparticles as the filler and poly(vinylidene fluoride) (PVDF) as the polymer matrix were fabricated by solution casting. At the same volume fraction, the BT@Al2O3/PVDF nanocomposites, with larger dielectric constant and higher energy density, outperformed the BT/PVDF nanocomposites. The 2.5 vol% BT@Al2O3/PVDF nanocomposites at 360 MV/m had a double more energy density than pure PVDF at 400 MV/m (6.19 vs. 2.30 J/cm3), and a remarkably 42% lower remnant polarization than the 2.5 vol% BT/PVDF nanocomposites (0.99 vs. 1.69 μC/cm2 at 300 MV/m). Such significant enhancement was closely related to the surface modification by Al2O3, which improved the insulation of BT nanoparticles and reduced the contrast of dielectric constant between the filler and the PVDF matrix.