The properties of nonstoichiometric lanthanum niobium oxide thin films formed using an e-beam deposition technique

► Molar ratio of the starting powders influences the stoichiometry of elements. ► The refractive index of lanthanum niobium thin films varies from 1.57 to 2.22. ► The optical band gap of formed thin films varies from 3.69 to 3.9 eV.