Revealing the mechanism of competing A‐site doping ions in (K, Na)NbO3‐based ceramics

Abstract Although past studies have shown a competitive relationship between bismuth ion (Bi 3+ ) and rare earth ions in potassium sodium niobate {(K, Na)NbO 3 , KNN}‐based ceramics, a comprehensive investigation of this competition has been relatively scarce. Herein, we conducted an in‐depth exploration of this competition by substituting Bi 3+ with praseodymium ions (Pr 3+ ) in KNN‐based ceramics possessing high piezoelectric properties. The substitution of Bi 3+ with Pr 3+ results in a decrease in the extent of multi‐phase coexistence at room temperature, an increase in domain size and grain size, and the enhancement of ferroelectricity. However, it also leads to a deterioration in piezoelectricity. Through a combination of experimental findings and first‐principles calculations, we analyzed the alterations in phase structure, ferroelectric domains, and electrical properties, attributing these changes to the competitive nature of Bi‐O and Pr‐O bonds with their distinct ionic/covalent characteristics. Consequently, this study not only unveils the underlying physical mechanism behind the competition between Bi 3+ and Pr 3+ ions in KNN‐based piezoceramics but also presents a novel approach to tailor the phase transition temperature, thereby facilitating the overall performance improvement of KNN‐based ceramics.