Enhancement of dielectric properties in (Na, K, Li)(Nb, Ta, Sb)O3-Bi0.5Li0.5ZrO3/polyvinylidene fluoride composites via solution-casting method

Abstract

Lead-free (Na, K, Li)(Nb, Ta, Sb)O₃-Bi_0.5Li_0.5ZrO₃ (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.

Graphical abstract

The alternative text for this image may have been generated using AI.