Nanoscale characterization and local piezoelectric properties of lead-free KNN-LT-LS thin films

We report the observation of domain structure and piezoelectric properties of pure and Mn-doped (K 0.44 ,Na 0.52 ,Li 0.04 )(Nb 0.84 ,Ta 0.1 ,Sb 0.06 )O 3 (KNN-LT-LS) thin films on SrTiO 3 substrates. It is revealed that, using piezoresponse force microscopy, ferroelectric domain structure in such 500 nm thin films comprised of primarily 180° domains. This was in accordance with the tetragonal structure of the films, confirmed by relative permittivity measurements and x-ray diffraction patterns. Effective piezoelectric coefficient ( d 33 ) of the films were calculated using piezoelectric displacement curves and shown to be ∼53 pm V −1 for pure KNN-LT-LS thin films. This value is among the highest values reported for an epitaxial lead-free thin film and shows a great potential for KNN-LT-LS to serve as an alternative to PZT thin films in future applications.