Optical absorption of gamma-irradiated lithium-borate glasses doped with different transition metal oxides

• Published in: Physica. B, Condensed matter Condensed matter, 2006-06, Vol.382 (1), p.340-351
• Main Authors: Marzouk, S.Y., Elalaily, N.A., Ezz-Eldin, F.M., Abd-Allah, W.M.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Energy gap; Exact sciences and technology; Gamma irradiation; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Oxides; Physical radiation effects, radiation damage; Physics; Structure of solids and liquids; crystallography; UV absorption; γ ray effects
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2006.03.014

We have investigated the effect of gamma irradiation on the optical properties of Li 2O–B 2O 3 containing two concentrations (0.2 or 0.5 g) of each one of the following transition metals, V, Mn, Fe or Ni oxide glass samples. We studied the impacts of gamma irradiation in terms of the mechanism by which radiation-induced defects are generated. A resolution of the observed absorption spectra showed several bands which were induced by photo-reduction or photo-oxidation assumed to take place by photo-chemical reaction according to the type of transition metal oxide (TMO). Small deviations of these induced bands characteristic of the glass constituents were observed and explained in terms of the physical properties, in relation to different oxidation states of TMO in the glass matrix. The series Mn 2+, Fe 2+ and Ni 2+ ions shows a trend of increased photo-oxidation with increasing electronegativity or decreasing mass of the ions. The prepared samples were studied in terms of their dosimetric characteristics: calibration curves from 1.0524 to 42.096 kGy and fading at (25 and 50 °C). Thermal bleaching of irradiated glass was found to permit the reduction of the larger part of TMO ions in Li 2O–B 2O 3. Also, the results showed that the degeneration of the induced bands was faster at 50 than at 25 °C. The optical energy gap E g was found to decrease with the increase of the radiation dose, and it is suggested that the mechanism of optical transition is forbidden by indirect transition.