Lead-free (Na, K, Li)(Nb, Ta, Sb)O3-Bi0.5Li0.5ZrO3 (NKLNTS-BLZ)/polyvinylidene fluoride (PVDF) composites with 0–3 connectivity were fabricated via a solution-casting method. The microstructure, phase evolution, and dielectric properties were systematically investigated as a function of filler content (0–40 vol%). SEM analysis revealed that fillers were well-dispersed at lower concentrations, significant agglomeration and micro-voids were observed at 40 vol%. The composites exhibited a giant dielectric constant, reaching a maximum of 250 (at 1 kHz) with 40 vol% loading. However, this enhancement was accompanied by a critical trade-off in dielectric loss and breakdown strength. To elucidate the conduction mechanism, AC conductivity was analyzed using Jonscher’s power law. The results showed that the power-law exponent (n) increased from 0.38 (pure PVDF) to ~ 0.6 (10–30 vol%), indicating a dominant hopping conduction mechanism desirable for insulation. Conversely, at 40 vol%, the n value dropped sharply to 0.27, signaling the onset of percolation and leakage currents. Consequently, the 30 vol% composition was identified as the optimal loading, effectively balancing high permittivity with electrical stability. These findings demonstrate that NKLNTS-BLZ/PVDF composites are promising candidates for next-generation embedded capacitors, provided that the filler fraction is optimized to mitigate conduction losses. High dielectric permittivity (εr ≈ 250) was achieved in solution-casting NKLNTS-BLZ/PVDF composites. A critical trade-off between high permittivity and breakdown strength was identified at high filler loadings (40 vol%). The 30 vol% composition was determined as the optimal loading, balancing dielectric performance with structural integrity. AC conductivity analysis via Jonscher’s power law confirmed a dominant hopping conduction mechanism (0.58 < n < 0.63) at optimal loadings. Interfacial polarization (MWS effect) and ceramic-polymer interaction are key drivers for the enhanced dielectric properties. These composites, with their high dielectric constants, show promise for use in lead-free capacitors and environmentally friendly electronics.
Bomlai et al. (Mon,) studied this question.