Alluri N.R., Song L., Girod S., Mandal B., Cardoletti J., Bobnar V., Granzow T., Kovacova V., Philippe A.M., Defay E., Glinsek S.
Journal of the European Ceramic Society, vol. 46, n° 6, art. no. 118077, 2026
K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> is among the most promising lead-free piezoelectrics. While its sputtered films match the performance of the champion piezoelectric Pb(Zr,Ti)O<sub>3</sub>, reproducible processing of high-quality and time-stable solution-deposited K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> films remains challenging. Here, we report 1 µm-thick Mn-doped K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> films prepared via a chemical solution deposition process, which have perfectly dense microstructure and uniform composition across their thickness. The films exhibit a high transverse piezoelectric coefficient (e <sub> 31 ,f</sub> = −15.4 C/m<sup>2</sup>), high dielectric permittivity (ε <sub>r</sub> ≈ 920), low dielectric losses (tan δ = 0.05) and can withstand electric fields up to at least 1 MV/cm. Their functional properties show excellent stability over time, and the synthesis process is reproducible. Furthermore, a surface acoustic haptic device based on K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> thin-film actuators is demonstrated. The results validate the high potential of Mn-doped K<sub>0.5</sub>Na<sub>0.5</sub>NbO<sub>3</sub> films to replace lead-based Pb(Zr,Ti)O<sub>3</sub> films in piezoelectric applications.
