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 SrTiO3 substrates. It is revealed that, using piezoresponse force microscopy, ferroelectric domain structure in such 500 nm thin films comprised of primarily 180 degrees 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 similar to 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.