Enhanced domain switching contributing to large strain response in (Bi_0.5Na_0.5)TiO₃–SrTiO₃ lead-free thin films

The acquisition of lead-free piezoelectric films with large strain is the key factor in promoting micro-actuator development. A lead-free compound, Bi_0.5Na_0.5TiO₃, exhibits extensive potential in achieving a large strain response and a high inverse piezoelectric coefficient. In this work, (1-x)Bi_0.5Na_0.5TiO₃-xSrTiO₃ (BNT-100xST, x = 0.1, 0.2, 0.25) solid solution thin films have been prepared using the chemical solution deposition method. The dielectric nonlinearity and ferroelectric properties of BNT-ST thin films have been systematically studied to investigate the domain wall motion in the films. The most significant domain wall motion was observed in BNT-20ST thin film, in which film a large strain of 0.89 % was obtained. In addition, the relationship between structure and properties as a function of temperature was studied by the temperature-dependent dielectric properties and Raman spectra analysis.