Texture-Engineered High-T_c KNbO₃–NaNbO₃ Piezoceramics with Enhanced d₃₃/d₃₃* and Energy-Harvesting Applicability by BaTiO₃ Chemical Modification: An Optimization Approach

This study demonstrates significantly enhanced the piezoelectric properties of lead-free (K 0.49 Na 0.49 Ba 0.02 )(Nb 0.98 Ti 0.02 )O 3 (KB1) ceramics through a combination of chemical modification and texture engineering. A significant breakthrough was achieved with the textured KB1 ceramic using 9 wt % NaNbO 3 template (KB1–9%NNT) particles. This ceramic demonstrated an enhanced piezoelectric charge constant ( d 33 ) of 210 pC/N, which is 1.64 times greater than that of nontextured KB1 ceramics. The planar electromechanical coupling coefficient ( k p ) of KB1–9%NNT was also significantly improved, reaching 33.11, which is 2.28 times higher than that of nontextured KB1. Furthermore, it exhibited a high piezoelectric strain coefficient ( d 33 *) of 330.23 pm/V and a large piezoelectric voltage coefficient ( g 33 ) of 101.76 × 10 –3 V m/N. These enhanced piezoelectric properties translated into a substantial figure of merit ( d 33 × g 33 = 23.37 × 10 –12 m 2 /N), signifying excellent energy-harvesting capabilities. Under a load resistance of 300 kΩ, it generated an impressive 20.60 V with a current of 68.68 μA, resulting in a power output of 1.41 mW and a power density of 36.09 μW/mm 3 . This generated power was sufficient to illuminate an NT3314 panel, consisting of 62 red light-emitting diodes (LEDs). These findings highlight the significant potential of the KB1–9%NNT ceramic for high-performance piezoelectric devices and energy-harvesting applications.