Improved dielectric properties of triphasic (NiFe2O4–2LaFeO3)–Ni–PVDF cermet–polymer composite films via magnetic field-assisted solidification.

In the quest for advanced composite materials with exceptional dielectric properties, in this work we investigated the preparation and performance of triphasic (NiFe2O4–2LaFeO3)–Ni–poly(vinylidene fluoride) (PVDF) cermet–polymer percolative composites. Utilizing a solution-casting technique for composite film formation, the research focuses on enhancing dielectric performance through the incorporation of electroceramic (NiFe2O4–2LaFeO3:NFO–2LFO), metallic nickel (Ni) fillers and magnetic field-assisted solidification. These composite films comprising a triphasic blend of magnetic electroceramic and metallic filler within a PVDF polymer matrix exhibited an intricate interplay between magnetic domains, crystalline phases, and polymer matrices. Applying a weak magnetic field during solidification facilitates the alignment of magnetic domains, leading to a 33% improvement in dielectric performance. Morphological analysis revealed homogeneous microstructures and well-defined interfaces. Through experimental measurements and percolation theory approximations, it is demonstrated that when the Ni content is close to the percolation threshold (fc), the dielectric constant due to space charge polarization of the composite with a 0.35 volume fraction of NFO–2LFO and a 0.18 volume fraction of Ni reached up to 595 with a low dielectric loss. These results highlight the critical role of interfacial polarization and magnetic field-induced alignment in enhancing the dielectric properties. The high magnetic responsiveness allows the fillers to magnetically aligned orientations within the PVDF polymer leading to significant gain in the performance. [ABSTRACT FROM AUTHOR]