Experimental determination of electrophoretic deposition parameters and electrical characterization for K _0.5 Na _0.5 NbO₃ perovskite thick films for energy harvesting applications

Globally, depleting non-renewable energy resources and environmental pollution are significant challenges. Much research is ongoing on perovskite coatings as a potential replacement. In this work, potassium sodium niobate (KNN) ceramics are fabricated by solid-state method, calcined at ∼850 °C, and electrophoreticcally deposited (EPD) on Ni-substrate uniquely then, sintered at high temperatures ∼1070–1120 °C. The X-ray diffraction and FTIR confirmed the development of a pure KNN perovskite structure and metallic bond groups (-O-Nb-O) present respectively. An increase in the sintering temperature resulted in the pronounced peaks observed in KNN ceramics, confirmed by Raman spectroscopy, and easily observed in SEM having “square” and “circular” morphology with grain growth. The coating thickness was measured around 18–116 μm and increasing deposition rate (0.084–0.337 μm/s) was calculated. The coating roughness (∼813 nm) was confirmed by atomic force microscopy. Complex impedance spectroscopic (CIS) analysis confirmed the high dielectric constant (∼4789) with a high transformation and curie temperature (T_O→T ∼ 280 °C & T_C ∼ 480 °C), respectively. The increasing conductivity (≥830 μS/m) at higher frequency and temperatures agree with the hopping conduction mechanism which confirmed the negative temperature coefficient of resistance (NTCR). The work holds great significance in sensors, actuators, spintronics, and energy harvesting applications.