Impacts of acceptor doping on the piezoelectric properties and domain structure in NBT-based lead-free ceramics

The domain structure and piezoelectric properties of Mn-doped 0.79(Na0.5Bi0.5)TiO3-0.14(K0.5Na0.5)TiO3-0.07BaTiO3 (BNBK79) ceramics were studied. The relationship between macroscopic properties and microstructure was established. The pure and Mn doped BNBK79 ceramics show different dynamic behavior in strain behavior and polarization hysteresis, due to the different domain structure and domain switching behavior. The BNBK79 ceramics show dominating irregular watermarks domain configuration before poling, changes to simple parallel stripes after poling, while BNBK79-Mn ceramics show more complicated domain configurations, where regular domain stripes containing Herringbones assembled with watermarks are dominated before poling, and the Herringbones remain after poling. The pinning effect induced by MnTi''−V0.. defect dipoles accounts for the complicated domain structure and hinders the domain switching, resulting in “hard” properties (low dielectric loss of 0.6% and high mechanical quality factor Qm of 1100), makes BNBK79-Mn ceramics promising for high-power piezoelectric applications.