Structure and domain wall dynamics in lead-free KNN-based ceramics

摘要

This paper comprehensively studied the effect of BaHfO3 doping on crystal structure, domain structure, and electrical properties of potassium sodium niobate ceramics, and especially analyzed the intrinsic structural characteristics of the R-O phase boundary, which can be successfully constructed through composition modification. Rietveld refinement and the piezoresponse force microscopy technique were combined to analyze the crystal structure and domain configuration of the material system. Comparative studies indicate that multiple phase coexistence will disturb the zigzag domains of the pure O phase into complex irregular domains, which are easier to switch under an external electric field, thus leading to improved electrical properties. Furthermore, the stabilized polarization state can be maintained under the thermal excitation due to the dominated O phase at high temperatures, which is beneficial for the temperature stability improvement. We believe that the structural analysis can give us a deeper understanding of the relationship among structural symmetry, domain dynamics, and electrical properties of potassium sodium niobate (KNN)-based ceramics.