Phase transitions and electrical behavior of lead-free (K0.50Na0.50)NbO3 thin film

Lead-free (K0.50Na0.50)NbO3 (KNN) thin films with a high degree of (100) preferred orientation were deposited on the SrRuO3-buffered SrTiO3(100) substrate by off-axis radio frequency magnetron sputtering. They possess lower phase transition temperatures (To-t∼120 deg. C and Tc∼310 deg. C), as compared to those of KNN bulk ceramic (To-t∼190 deg. C and Tc∼400 deg. C). They also demonstrate enhanced ferroelectric behavior (e.g., 2Pr=24.1 μc/cm2) and fatigue endurance, together with a lower dielectric loss (tan δ∼0.017) and a lower leakage current, as compared to the bulk ceramic counterpart. Oxygen vacancies are shown to be involved in the conduction of the KNN thin film.