High Dielectric Constant and Low Percolation Threshold in Poly(vinylidene fluoride) Composite Films Containing Mechanochemically Synthesized BaSnF₄ Nanowires

We prepared BaSnF4 nanowires (NWs) with a high dielectric constant using a simple high-energy ball-milling method and investigated the dielectric properties of polymer composites containing inorganic fluoride fillers. We employed various techniques, such as powder X-ray diffraction, scanning and transmission electron microscopy, and elemental mapping analysis using energy-dispersive X-ray spectroscopy, and we showed that the morphology of BaSnF4 changed from microparticles consisting of aggregated flakes to NWs as applied kinetic energy increased. A comparison of composite films containing two fillers confirmed that the dielectric constant and AC conductivity of BaSnF4 NWs at 30 vol % were two to three times higher than those of aggregated nanoparticles. Even though the breakdown strength was low at a high volume fraction, these results indicate that BaSnF4 NWs are extremely promising materials for the development of high-κ nanocomposites for various dielectric applications.