Piezoresponse and ferroelectric properties of lead-free [Bi_(0.5)(Na_(0.7)K_(0.2)Li_(0.1))_(0.5)]TiO_3 thin films by pulsed laser deposition

摘要

Polycrystalline lead-free piezoelectric [Bi_(0.5)(Na_(0.7)K_(0.2)Li_(0.1))_(0.5)]TiO_3 (BNKLT) thin films were grown on Pt/Ti/SiO_2/Si substrates using pulsed laser deposition (PLD). In this letter, we report the ferroelectric properties and piezoresponse of the PLD-produced BNKLT thin films. X-ray diffraction characterization revealed a good crystallinity and a pure perovskite structure in the films. The films exhibited a well-defined polarization hysteresis loop with a remnant polarization P_r of 13.9 μC/cm~2 and a coercive field E_c of 10.2 MV/m. The domain structure and its thermal-driven evolution from the ferroelectric to nonferroelectric phase were observed by piezoresponse force microscopy. The results were consistent with the phase transition profile of BNKLT bulk ceramics. Typical butterfly-shaped piezoresponse loop was obtained and the effective piezoelectric coefficient d_(33,f) of the BNKLT thin films was about 64 pm/V.