Dielectric and Ferroelectric Properties of Sr_xBa_(1-x)Nb_2O_6 (SBN:x) Thin Films

摘要

Thin films of Sr_xBa_(1-x)Nb_2O_6 (SBN:x) are particularly attractive for 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 percent) and annealing conditions. It is maximum, at theferroelectric-paraelectric transition temperature of the film (175 deg C, 116 deg C and 40 deg Cforx = 50, 60, and 70 percent respectively). At room temperature and with a Sr content of 60 percent, the relative variation of the dielectric permittivity [epsilon(0)-epsilon(E)]/epsilon(0) is found equal to 46 percent 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.