Characterization of domain structure and domain wall kinetics in lead-free Sr²⁺ doped K_0.5Na_0.5NbO₃ piezoelectric ceramics by piezoresponse force microscopy

The domain structure and local polarization reversal were studied in lead-free ceramics (K_0.5Na_0.5)_1-2xSr_xNbO₃ by various modes of scanning probe microscopy. It was shown that the increase in Sr concentration led to a decrease in both grain and domain sizes. The local polarization reversal study provided important information on the domain wall dynamics in this complicated system. The defect distribution in doped ceramics was proposed as a major factor limiting domain wall mobility and internal bias field decrease together with the increase of the activation field for domain wall motion.