Superior piezoelectricity in lead-free barium titanate piezoceramics

Since the 21st century, increasing environmental protection and human health concern have been the driving force to develop lead-free piezoelectric materials with enhanced performances, and phase engineering strategy has been validated to be a viable method in numerous methodologies. Here, we gained a superb d33∼(637 ± 30) pC/N in lead-free (1–x)(Ba0.93Ca0.07)(Sn0.08Ti0.92)O3-x(Sb0.5Li0.5)TiO3 [abbreviated as (1–x)BCST-xSLT, 0 ≤ x ≤ 0.4% (in mole)] piezoelectrics utilizing chemical doping. To illustrate the relationship among composition-structure-performance, microstructure characterization, electrical properties measurement, first-principles calculation, and phase-field simulations were performed. Atomic-resolved polarization mapping of z-contrast imaging manifests the ferroelectric three phases (RO–T) coexist at the nanoscale with nanoscale polarization switching among them. Theoretical calculations and simulations confirm that the high-density nano-domain boundary bridges the polyphase coexisting nano-domains, which makes the polarization reversal easy, thus significantly reducing the energy barrier and polarization anisotropy among different phases.