  We report on optical properties of reduced BaTiO3-d at different doping
levels including insulating and metallic samples. In all the samples, including
metallic one, we observe structural phase transitions from the changes in the
infrared-active phonon modes. Metallic ground state is confirmed by the
Drude-type lowfrequency optical reflectance. Similar to SrTiO3-d we find that
the midinfrared-absorption band in BaTiO3-d appears and grows with an increase
in the oxygen-vacancy concentration. Upon decrease in temperature from 300 K,
the midinfrared band shifts slightly to higher frequency and evolves into two
bands: the existing band and a new and smaller band at lower frequency. The
appearance of the new and smaller band seems to be correlated with the
structural phase transitions
