Multicomponent modified perovskite lead-free KNN ceramic to establish R–T phase boundary near room temperature for energy acquisition and harvesting

We report the construction of PZT like R–T phase boundary in KNN-based ceramic near room temperature for high piezoelectric response by merging of R–O and O–T phase boundaries as a result of incorporating Bi_0.5Na_0.5TiO₃ and Bi_0.5K_0.5ZrO₃ into KNN ceramic matrix via solid state reaction. The XRD revealed the existence of R–T phase boundary at optimized sintering temperature of 1060 °C. Scanning electron microscopy (SEM) technique was employed to investigate the morphology of the grains. Dielectric measurement showed high dielectric constant value and low dielectric loss with Curie temperature at 391 °C. The activation energy extracted from a DC conductivity plot of ceramics using the Arrhenius equation is found to be 0.43 eV. Remnant and spontaneous polarization showed a constant value of 11.38 µC/cm² and 22.50 µC/cm², respectively, even after exposure of 10⁴ cycles of electric fields. High piezoelectric charge coefficient of 407 pC/N makes the system highly competitive for energy harvesting applications. Flexible energy harvesters were fabricated at optimized ceramic to polymer ratio with an aim of optimizing the composition, ensuring the desired balance of piezoelectric and ferroelectric characteristics. Microgenerator at 30 wt% composition exhibited a significant open-circuit output voltage of 24.8 V and short-circuit current of 6.5 µA under gentle finger tapping, highlighting material’s efficiency in harvesting energy from low-frequency vibrations.