Dice-and-fill processing and characterization of microscale and high-aspect-ratio (K, Na)NbO3-based 1–3 lead-free piezoelectric composites

Abstract Piezoelectric composites with high-aspect-ratio lead-free piezoelectric microrods embedded in a polymer matrix were fabricated by applying the modified dice-and-fill method to a (K,Na)NbO 3 -based piezoelectric ceramic, 0.9475[Li 0.02 (K 0.48 Na 0.53 ) 0.98 ](Nb 0.80 Ta 0.20 )O 3 –0.0525AgSbO 3 –0.5 wt% MnO 2 (abbreviated as LKNNT–AS–M) with enhanced piezoelectricity but low mechanical strength. The Pb-free LKNNT–AS–M/polymer composite specimens containing ∼10–23 vol% ceramic pillars with sectional width ∼50 μm, separation ∼55–110 μm and high aspect ratio ∼11, were prepared and investigated with an emphasis on their electrical properties. The developed composites possess a higher thickness factor k t ∼63–67%, lower planar factor k p ∼27–34% and enhanced k t / k p ratio ∼2.3. The composites also possess favorable properties which includes low electrical (tan δ ∼0.029) and mechanical ( Q m ∼6) losses, low acoustic impedance Z ∼4.2–7.8 Mrayl and ∼5 times higher voltage coefficient g 33 compared to LKNNT–AS–M piezoceramic. The promising results indicate that the LKNNT–AS–M/polymer composites have the potential to be used as active elements in high performance ultrasonic transducers.