Optical anisotropy and dielectric parameters of (Ba$_{0.5}$Sr$_{0.5}$)Nb$_{2}$O$_{6}$ films on a Pt(111)/Si(001) substrate

(Ba$_{0.5}$Sr$_{0.5}$)Nb$_{2}$O$_{6}$ films were synthesized on a Pt(111)/Si(001) substrate by RF gas-discharge sputtering in pure oxygen atmosphere. It was found that the films have a dominant crystallographic orientation in the [001] direction and natural unipolarity, which was revealed through analysis of dielectric and piezoelectric parameters. It was demonstrated that the optical parameters of film material in the (Ba$_{0.5}$Sr$_{0.5}$)Nb$_{2}$O$_{6}$/Pt(111)/Si(001) heterostructure match those typical for a (Ba$_{0.5}$Sr$_{0.5}$)Nb$_{2}$O$_{6}$ single crystal.