Dielectric and ferroelectric properties of SrxBa1-xNb2O6 (SBN:x) thin films

Thin films of SrxBa1-xNb2O6 (SBN: x) areparticularly attractivefor their potential use as low voltage electro-optic waveguides. This potential application in integrated optics requires the control of the (001) oriented SBN growth on a conductive substrate. We have prepared (001) SBN:x thin films on Pt coated MgO substrates by using sputtering techniques and rapid thermal annealing. The dielectric non linearity of the SBN:x films is investigated as a function of the Sr content (x = 50,60, or 70%) and annealing conditions. It is maximum at theferroelectric-paraelectric transition temperature of the film (175 degrees C, 116 degrees C and 40 degrees C for x = 50, 60, and 70% respectively). At room temperature and with a Sr content of 60%, the relative variation of the dielectric permittivity [epsilon(0)-epsilon(E)]/epsilon(0) is found equal to 46% for an applied electric field E = 43 kV/cm. Due to a transition temperature closer to room temperature, a dielectric non linearity of higher value, less sensitive to temperature and little affected by hysteresis, is expected from films of higher Sr content.