Optical characterization of some rare earth ions doped bismuth borate glasses and effect of gamma irradiation

Rare earth doped bismuth borate glasses were prepared by conventional melt annealing method. The density, molar volume, ultraviolet, visible, and infrared spectroscopic and optical energy band gap of these glasses have been measured or calculated and employed to investigate the prepared glassy samples. The refractive index and molar refraction have been calculated using the theory of reflectively of light. The luminescence properties of the glasses were analyzed. The undoped glass shows strong extended UV-near visible absorption bands which are attributed to the collective presence of both trace iron impurities from raw materials and also the sharing of bismuth Bi+3 ions. The rare earth doped samples show the same strong UV-near visible bands as the undoped sample beside extra characteristic bands due to the respective rare earth ions. Results showed that the luminescence intensity changed with different rare earth oxides. The decreasing values of optical band gap and band tail can be understood and related in terms of the structural changes that are taking place in the glass samples. The infrared absorption spectra of the prepared glasses show characteristic absorption bands related to the borate network (BO3, BO4 groups) together with vibrational modes due to Bi-O groups. The IR spectra are slightly affected by gamma irradiation indicating the stability of the structural glassy forming units. The prepared samples reveal varying responses towards the effect of gamma irradiation. (C) 2012 Elsevier B.V. All rights reserved.