Dielectric and ferroelectric properties of thin heteroepitaxial films of SBN-50

The phase transformations and ferroelectric characteristics of thin heteroepitaxial barium-strontium niobate SBN-50 films grown by RF cathode sputtering in an oxygen atmosphere were studied using dielectric spectroscopy and scanning probe microscopy (in the modes of force microscopy of the piezoresponse and Kelvin modes). It is shown that the films are characterized by a low surface roughness, an average size of ferroelectric domains of $\sim$ 100 nm, and spontaneous polarization directed from the substrate to the film surface. Differences in the magnitude of the surface potential signal and its relaxation for the regions polarized at +10 V and -10 V were established. The nature of the change in the dielectric parameters in the temperature range $T$ = 275–500 K indicates that the material belongs to ferroelectric relaxors. The reasons for the established regularities are discussed.