Lead-Free Piezoelectric (K,Na)NbO3 Thin Films Derived from Metal Alkoxide Precursors

Lead-free piezoelectric K 0.5 Na 0.5 NbO 3 thin films for microelectromechanical systems were fabricated via chemical solution process using metal alkoxide. Perovskite K 0.5 Na 0.5 NbO 3 (KNN) single-phase thin films with good leakage current properties were successfully prepared by optimizing the K x Na x NbO 3 ( x ≧0.5) composition of the precursor solution. The KNN thin films prepared from the solution with K 0.55 Na 0.55 NbO 3 composition showed typical ferroelectric P – E hysteresis and field-induced strain loops. The 2 P r and 2 E c values of the K 0.55 Na 0.55 NbO 3 films were 14 µC/cm 2 and 140 kV/cm, respectively. From the slope of the field-induced butterfly loop, the effective d 33 was found to be 46 pm/V.