Texture-Engineered High-Tc 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_0.49Na_0.49Ba_0.02)(Nb_0.98Ti_0.02)O₃ (KB1) ceramics through a combination of chemical modification and texture engineering. A significant breakthrough was achieved with the textured KB1 ceramic using 9 wt % NaNbO₃ template (KB1–9%NNT) particles. This ceramic demonstrated an enhanced piezoelectric charge constant (d₃₃) 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 (d₃₃*) of 330.23 pm/V and a large piezoelectric voltage coefficient (g₃₃) of 101.76 × 10^–3 V m/N. These enhanced piezoelectric properties translated into a substantial figure of merit (d₃₃ × g₃₃ = 23.37 × 10^–12 m²/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/mm³. 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.