Enhanced Electromechanical Properties and Temperature Stability of Textured (K0.5Na0.5)NbO3-Based Piezoelectric Ceramics

In this work, we report the electromechanical properties of < 00l >(C)-textured (K0.5Na0.5)(0.98)Li0.02NbO3 (KNLN) and (K0.5Na0.5)(Nb0.85Ta0.15)O-3 (KNNT) ceramics produced by templated grain growth. Both materials show high texture quality (F-00l = 98% and full-width at half-maximum [FWHM] = 8.4 degrees for KNLN, F-00l = 99%, and FWHM = 7.6 degrees for KNNT) and enhanced piezoelectric response compared with randomly oriented ceramics. However, textured KNLN shows higher piezoelectric properties (d(33) = 192 pC/N, k(p) = 0.63, k(31) = 0.39, d(31) = -73 pC/N, d*(33) = 208 pC/N) and higher phase transition temperatures (To-t = 155 degrees C, T-c = 439 degrees C) than textured KNNT. The enhanced room-temperature piezoelectric properties are associated with low-strain hysteresis (4.0%), suggesting that < 00l >(C) textured and poled orthorhombic KNLN may exhibit domain engineering character. The piezoelectric performance of textured KNLN with To-t = 155 degrees C is high and stable over a wide temperature range (-60 degrees-100 degrees C), strongly favoring use of this material in device applications compared with the modified KNN-based materials with a To-t near room temperature.