Low voltage tunability of PVDF-based nanocomposites by interface polarization induced by TiO2-coated BST core-shell nanoparticle

Polymer-based flexible materials can be slated as successors of conventional inorganic ferroelectrics to induce tunable dielectric properties in microwave devices because of their advantageous characteristics, such as lightweight, flexibility, easy processibility, and eco-friendliness. Ferroelectric polymers require a high external field to induce dielectric tunability, which can be a problem. Another problem is the dielectric mismatch and incompatibility between ceramic and polymer, which hinders the ceramic-polymer composites to induce tunable dielectric properties. Herin, titanium oxide-barium strontium titanate (TO@BST) core-shell nanoparticle are reinforced into the poly (vinylidene fluoride) (PVDF) matrix to fabricate flexible nanocomposite with tunable dielectric properties. The core-shell nanoparticle-based nanocomposite produced low voltage dielectric tunability (12.03 % at 33 kV/mm) and excellent tunable dielectric efficiency (TuE, 0.8 %) while maintaining low dielectric loss (tanδ, 0.024). Moreover, TO@BST-based nanocomposite exhibited a remarkable 91 % improvement in dielectric constant compared to pure PVDF and a 25.7 % improvement compared to BST-based nanocomposite. The dielectric breakdown strength (Eb) of the nanocomposite filled with 40 wt% TO@BST nanoparticle improved by 45 % (114.36 kV/mm) compared to pure BST-based nanocomposite (78.68 kV/mm). This work provides valuable insights into designing novel flexible nanocomposites with low voltage tunability and high breakdown strength at high filler loading.