Structural and dielectric properties of the lead-free (1−x)K0.5Na0.5NbO3-xSrTiO3 thin films from solutions

According to XRD, the films crystallized in perovskite phase upon heating at 750 °C. By increasing the STO content in the films, the monoclinic distortion, the volume of the unit cell and the degree of preferential (1 0 0) orientation decreased. The latter was explained as due to the differences in the average surface charges of the KNN and STO end members in the system. The microstructures of KNN-STO films consisted of small, equiaxed grains, of about 60 nm across notwithstanding the composition. The dielectric permittivity-maximum versus temperature decreased with increasing STO content in the films, and it was observed that the respective values were lower than those reported for bulk materials. The 0.925KNN-0.075STO film exhibited a typical relaxor behavior with a slim polarization-electric field loop.