Achieving excellent mechanical and electrical properties in transition metal oxides and rare earth oxide‐doped KNN‐based piezoceramics

AbstractPotassium sodium niobate (KNN)‐based piezoelectric ceramics have emerged as a promising alternative to lead‐based systems due to their exceptional properties. While extensive research has focused on improving the electrical properties of KNN‐based ceramics through doping and processing optimization, the concurrent investigation of their mechanical properties has been lacking. This study presents a comprehensive analysis of the mechanical and electrical properties of KNN‐based lead‐free piezoceramics doped with various transition metal oxides and rare earth oxides, based on substantial experimental data. Our findings reveal that the as‐sintered KNN‐based ceramics exhibit not only outstanding electrical properties but also remarkable mechanical robustness compared to conventional toughened lead zirconate titanate (PZT)‐based ceramics. These exceptional electrical and mechanical properties are attributed to the micro‐scale and atomic‐scale structure of the modified KNN‐based ceramics, characterized by a highly condensed structure, an inhomogeneous distribution of nano‐domain structure, and the presence of amorphous intergranular films at grain boundaries.