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

Abstract

Lead-free piezoelectric K0.5Na0.5NbO3 thin films for microelectromechanical systems were fabricated via chemical solution process using metal alkoxide. Perovskite K0.5Na0.5NbO3 (KNN) single-phase thin films with good leakage current properties were successfully prepared by optimizing the KxNaxNbO3 (x≧0.5) composition of the precursor solution. The KNN thin films prepared from the solution with K0.55Na0.55NbO3 composition showed typical ferroelectric P–E hysteresis and field-induced strain loops. The 2Pr and 2Ec values of the K0.55Na0.55NbO3 films were 14 µC/cm2 and 140 kV/cm, respectively. From the slope of the field-induced butterfly loop, the effective d33 was found to be 46 pm/V.

Growth and physical properties of highly oriented La-doped (K,Na)NbO3 ferroelectric thin films

“…It should be noted that no differences were observed when analyzing the TGA-DTA curves of the KNN and KNN-La with an excess of alkaline metals. authors [17,18]. Nevertheless, in our study, when the precursor solutions are prepared adding 20 mol% (70/70) excess of alkali metals, the thin films exhibit a well-crystallized KNN and KNN-La phase and no evidence of secondary phases is detected.…”

Development of KNN-Based Piezoelectric Materials

“…The main principle of SSCG method is based on abnormal grain [120][121][122] synthesized the KNN single crystal by SSCG method using (110) oriented KTaO 3 crystal as seed. The crystals had largest dimension up to 4 mm but did not exhibit full density as shown in Fig.…”

Lead-Free KNN-Based Piezoelectric Materials

“…Due to the volatility of sodium and potassium, adding an excess amount of these elements in precursors can compensate for the loss of A-site elements and result in films with improved properties [77][78][79][80][81][82]86]. Excess sources of Na and K largely suppress the formation of cation and anion vacancies in the films, eliminate the formation of secondary phases such as K 4 Nb 6 O 17 , and improve the surface roughness.…”