Diffused and successive phase transitions of (K, Na)NbO3‐based ceramics with high strain and temperature insensitivity

Abstract

AbstractPhase boundaries realize enhanced piezoelectricity in lead‐free (K, Na)NbO3‐based ceramics but suffer from the weakness of undesirable temperature sensitivity. Here, an effective method is designed to develop temperature‐insensitive piezoelectricity (small signal piezo‐coefficient [d33] and large signal piezo‐coefficient []) in KNN‐based piezoceramics by constructing the diffused and successive phase transitions, which results in a broadness of the optimal temperature range of the electrical properties. The room‐temperature value in KNN‐based ceramics modified with BaZrO3 and (Bi0.5Na0.5)HfO3 reaches as high as 540 (±10) pm V−1, which is higher than PZT‐5H and most reported KNN‐based systems. Notably, superior temperature insensitivity of the and Pr values is also observed among the diffused and successive phase transitions region (20‐100°C), with <5% fluctuation. In addition, the in situ temperature‐dependent d33 measurement shows a high‐temperature reliability and less fluctuation (<15%) in a wide temperature range (20‐120°C). These results open a new window for further development of highly temperature‐insensitive lead‐free piezoceramics.