Phenomenal Improvement of Piezoelectric Voltage Coefficient in [00l] Textured K0.5Bi0.5TiO3 Ceramics

Abstract

[00l] textured K0.5Bi0.5TiO3 ceramics were fabricated via the reactive template grain growth technique and tape-casting. Plate-like morphology of perovskite K0.5Bi0.5TiO3 powder was achieved via the topochemical conversion of K0.5Bi4.5Ti4O15 (4-layers Aurivillius oxide) template. A Lotgering factor of 71% and large plate-like grains with an aspect ratio of ∼ 12 were observed in textured K0.5Bi0.5TiO3 (KBT-T) ceramics. Poled KBT-T ceramics exhibited a much lower RT dielectric constant of ∼160 and significantly improved d33 ∼ 135 pC/N as compared to KBT ceramics with randomly oriented grains (KBT-R). Impressively, the obtained value of piezoelectric voltage coefficient (g33 ∼ 95×10−3 Vm/N) for KBT-T ceramics is the highest ever reported for lead-free piezoceramics, which is an almost 500% increase over the KBT-R sample (g33 ∼ 16×10−3 Vm/N). The piezoelectric energy harvesting capability of the KBT-T sample was demonstrated by the observed peak-to-peak output voltage ∼ 7.5 V and current ∼ 2 μA under a finger tapping motion. The remanent polarization value (Pr ≈ 20 μC/cm2 at an applied electric field of 80 kV/cm) of the KBT-T ceramic was significantly higher than that of the KBT-R sample (Pr ≈ 12 μC/cm2).