High Piezoelectric and Mechanical Properties for (K,Na)NbO ₃ -Based Textured Piezoceramics

(K,Na)NbO 3 -based ceramics are promising lead-free piezoelectrics due to their excellent piezoelectric coefficient ( d 33 ) and high Curie temperature ( T c ), but their poor mechanical properties limit high-reliability applications. To address this issue, 0.97K 0.5 Na 0.5 Nb 0.95 Sb 0.05 O 3 -0.03Bi 0.5 Na 0.5 ZrO 3 -0.5%wtBiFeO 3 - x ZrO 2 (KNNS- x ZrO 2 ) textured ceramics were developed. Excessive ZrO 2 improved mechanical performance, while <001>-oriented samples exhibited strong piezoelectricity. At x = 0.01, the ceramics achieved high values in the KNN system: d 33 ∼ 326 pC·N −1, H v ∼ 8.46 ± 0.14 GPa, E ∼ 172 ± 4 GPa, and fracture toughness K IC ∼ 1.70 ± 0.09 MPa·m 1/2 . Based on these outstanding properties, a KNNS-0.01ZrO 2 piezoelectric wristband was fabricated to monitor human heart rate, producing stable current signals under different motion states. This work provides insights for reliable piezoelectric sensors and actuators.