SOME EFFECTS OF THE ADDITION OF IRON-OXIDE AND OF ANNEALING ON THE OPTICAL AND INFRARED-ABSORPTION SPECTRA OF SODIUM TETRABORATE GLASSES

The optical and infrared absorption spectra of sodium tetraborate glasses containing iron oxide have been studied as a function of iron content. It was found that the addition of iron oxide shifts the optical absorption edges towards lower energies and introduces a new absorption band as compared with the optical absorption spectrum of pure sodium tetraborate glass. The addition of iron does not introduce any new absorption band in the infrared spectrum of pure sodium tetraborate glass. The measurements were made on unannealed samples and samples annealed at different temperatures.