Diffused and successive phase transitions of (K, Na)NbO 3 ‐based ceramics with high strain and temperature insensitivity

Abstract Phase boundaries realize enhanced piezoelectricity in lead‐free (K, Na)NbO 3 ‐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 d 33 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 BaZrO 3 and (Bi 0.5 Na 0.5 )HfO 3 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 P r 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 d 33 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.