Optical properties of reduced LiNbO₃

Abstract

Optical characteristics of H2-reduced LiNbO3 have been studied. The optical transmission in the spectral range 0.3 to 5 mu m is progressively narrowed as the sample is reduced. An absorption band centred at about 2.48 eV is assigned to small polarons. This interpretation is consistent with the published defect structure, transport and spectroscopic reports on reduced LiNbO3. A semi-quantitative analysis of the 2.48 eV absorption band is carried out by employing the Reik and Heese theory (1967) for optical properties of small polarons.