Piezoresponse and ferroelectric properties of lead-free [Bi 0.5(Na0.7K0.2Li0.1) 0.5]Ti O3 thin films by pulsed laser deposition

Abstract

Polycrystalline lead-free piezoelectric [Bi0.5(Na 0.7K0.2Li0.1)0.5]Ti O3 (BNKLT) thin films were grown on PtTiSi O2 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 Pr of 13.9 μC cm2 and a coercive field Ec of 10.2 MVm. 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 d33,f of the BNKLT thin films was about 64 pmV. © 2008 American Institute of Physics.