Optical properties of barium strontium niobate SBN61 films

Heteroepitaxial Sr$_{0.61}$Ba$_{0.39}$Nb$_{2}$O$_{6}$ films have been formed on MgO(001) substrates by RF deposition in an oxygen atmosphere. The film orientation with respect to the substrate is investigated using X-ray diffraction. The permittivity dispersion parameters in the visible range are determined by measuring optical transmission spectra. The films are found to have a wider band gap and a smaller refractive index as compared with the single-crystal material.