Influence of gamma irradiation on the refractive index of Fe-doped barium titanate thin films

Polycrystalline Fe-doped barium titanate (Fe-doped BaTiO3) thin films were grown by thermal decomposition of the precursors deposited from a sol–gel system onto quartz substrates. The changes in the transmittance spectra induced by gamma irradiation on the Fe-doped BaTiO3 thin films were quantified. The values for the optical energy band gap were in the range of 3.42–3.95 eV depending on the annealing time. The refractive index of the film, as measured in the 350–750 nm wavelength range was in the 2.17–1.88 range for the as prepared film, and this increased to 2.34–1.95 after gamma irradiation at 15 kGy. The extinction coefficient of the film was in the order of 10−2 and increased after gamma irradiation. We obtained tuneable complex refractive index of the films by exposure to various gamma rays doses.