Structure, the lattice dynamic, and the dielectric characteristics of Sr$_{0.5}$Ba$_{0.5}$Nb$_{2}$O$_{6}$ films

Solid solution Sr$_{0.5}$Ba$_{0.5}$Nb$_{2}$O$_{6}$ films have been synthesized on a (111)Pt/(001)Si substrate by rf deposition in an oxygen atmosphere. The depolarized Raman spectra, the structure, and the dielectric characteristics of the films have been studied over a wide temperature range. It is found that the films were singlephase, had the tetragonal tungsten bronze structure, and had a pronounced axial texture with axis 001 directed perpendicular to the substrate surface. It is shown that the film material undergoes a diffuse phase transition to the state of a relaxor ferroelectric in the temperature range 300–425 K. Possible reasons of the regularities observed are discussed.