Multifunctional lead-free K0.5Bi0.5TiO3-based ceramic reinforced PVDF matrix composites

Abstract

This work aims for the experimental verification of the proposed models for the dielectric and piezoelectric behavior of the polymer-ceramic composites and designing a new composite material with excellent piezoelectric performance. The lead-free piezocomposites were fabricated via hot-press technique with various volume fraction of 0.95K0.5Bi0.5TiO3–0.05BiAlO3 (abbreviated as KBT-5BA) ceramic fillers embedded in polyvinylidene fluoride (PVDF) matrix. The fabricated composite system was further characterized for thermal, structural, and electrical properties. The addition of ceramic filler resulted in better thermal stability, an apparent evolution of ferroelectric β-phase over the other non electroactive phases due to electrostatic interaction at the ceramic-polymer interface, and a significant increase in the dielectric and piezoelectric performance. The dielectric permittivity of the composite with respect to filler volume was found to be well fitted by the Yamada model. Further, a noticeable change in the value of the shape parameter for composite with low and high volume fractions of the ceramic was discerned. The optimum dielectric response with εr ~112 at 1 MHz and piezoelectric coefficients d33 ~30 pC/N and g33 ~ 32 mV m/N were observed for the composite with optimized filler content. These results extend the feasibility of lead-free polymer ceramic composite materials for the development of piezoelectric devices.