Enhanced ferroelectric properties in Mn-doped K_0.5Na _0.5NbO₃ thin films derived from chemical solution deposition

Mn-doped K_0.5Na_0.5 NbO₃ (KNN) thin films derived from chemical solution deposition have been investigated. 2 mol % manganese acetate was introduced into the polyvinylpyrrolidone-modified KNN precursor solution to prepare the KNN thin films. It was found that Mn doping can increase the dielectric constant and decrease the dielectric loss, as well as significantly decrease the leakage current. The leakage current density of Mn-doped KNN film is about 3× 10^-6 A/cm² at an electric field of 50 kV/cm, which is 10⁴ times lower than that of the undoped film (about 3× 10^-2 A/cm²). These are attributed to the decrease in the concentration in oxygen vacancies and free carrier-holes by increasing the valence of Mn during thermal treatment. As a result, well saturated polarization-electric field hysteresis loops were obtained in the Mn-doped KNN thin films.