Piezoelectric K0.5Na0.5NbO3 thick films derived from polyvinylpyrrolidone-modified chemical solution deposition

Lead-free K0.5Na0.5NbO3 (KNN) ferroelectric films with enhanced thickness of 3.5 mu m were prepared by a polyvinylpyrrolidone-modified chemical solution deposition method. A single perovskite phase with a dense morphology and (100) orientation was obtained at relatively low annealing temperature of 600 degrees C. A large effective piezoelectric coefficient d(33), of 61 pm/V was demonstrated at 100 kHz without considering the substrate clamping effect. A well-saturated polarization hysteresis loop was obtained with a high remnant polarization P-r of 16.4 mu C/cm(2). These results showed that KNN is a promising lead-free piezoelectric film candidate, and that crystallizing the film at low processing temperature to obtain (100) orientation and dense morphology is critical to achieving excellent ferroelectric and piezoelectric properties. (c) 2008 American Institute of Physics.