The structure, dielectric, and optical properties of $c$-oriented SBN-50 films grown on Pt/Al$_{2}$O$_{3}$ substrate

Studies of the structure, dielectric and optical properties of thin films of a relaxor ferroelectric Ba$_{0.5}$Sr$_{0.5}$Nb$_{2}$O$_{6}$ grown on Pt(111)/Al$_{2}$O$_{3}$ ($c$-cut) substrate by high-frequency RF-sputtering in oxygen atmosphere, were performed. X-ray diffraction studies showed that Ba$_{0.5}$Sr$_{0.5}$Nb$_{2}$O$_{6}$ films are $c$-oriented. The unit cell parameters in the tetragonal approximation were $c$ = 3.949(1)$\mathring{\mathrm{A}}$ and $a$ = 12.38(1) $\mathring{\mathrm{A}}$. It was established that the ferroelectric–paraelectric phase-transition temperature rises and optical anisotropy increases in the object in comparison with the bulk material. Reasons for the elucidated regularities are discussed.