A series of 26 (Ba1-xSrx)(y)TiO2+y thin films with 0.22 less than or equal to y less than or equal to 1.01 and x < 0.07 were grown by metalorganic chemical vapor deposition. Most of the films with 0.22 less than or equal to y less than or equal to 0.37 were fully amorphous, whereas the films with 0.43 less than or equal to y < 1 were composed of crystalline (Ba,Sr)-TiO3 and a Ti-rich amorphous phase. Transmission spectra were measured and analyzed to determine the optical constants of the films, including the optical gap, which was found to decrease as y increased. An effective medium model was used to estimate the volume fraction of amorphous material in the two-phase films from the transmission spectra, by assuming that the two phases each had a fixed optical gap.