High piezoelectric performance in lead-free (K, Na)NbO3 ceramics under a low driving field.

In this work, lead-free (K 0.485 Na 0.485 Li 0.03)Nb 0.8 Ta 0.2 O 3 composition was designed to control the orthorhombic-tetragonal phases boundary near the room temperature as confirmed by Rietveld analysis, high-angle annular dark field scanning transmission electron microscopy, and temperature dependent dielectric constant. A comparative study of the direct and indirect synthesis methods was carried out and their functional properties were optimized as a function of sintering temperature (T s) and dwell time. Here, we achieved a large dynamic piezoelectric constant (d 33 *) of 510 pm/V under a very low electric field of 15–30 kV/cm. Moreover, an enhanced static piezoelectric constant (d 33) of 335 pC/N was obtained with a high Curie temperature (T C) of 315 °C. The large d 33 and d 33 * simultaneously with high T C in a single composition are promising results in lead-free polycrystalline ceramics. The strategic design of this work opens a new door for the possible development of novel functional materials for device applications. [ABSTRACT FROM AUTHOR]