Comparative optical, FTIR and photoluminescence spectral analysis of copper ions in BaO–B2O3, SrO– B2O3 or Bi2O3– B2O3 glasses and impact of gamma irradiation

Abstract

Three basic borate glasses were prepared from the systems (BaO–B2O3), (SrO–B2O3) and (Bi2O3–B2O3) together with samples doped with 0.25% CuO from the three systems. Collective characterizations of the optical, FTIR, photoluminescence spectra of the prepared glasses were carried out before and after impinging to gamma irradiation. The results were analysed in relation with the structural building groups and their housing in the glass network. Optical spectra of the alkaline earth borates reveal distinct UV absorption bands due to unavoidable trace iron impurities (Fe3+ ions). While the Bi2O3–B2O3 glass shows an additional near visible band related to absorption of Bi3+ ions. The CuO doped glasses exhibit distinct greenish blue colors imparting an additional very broad visible near IR band in all samples due to octahedrally coordinated Cu2+ ions. FTIR spectra of the two glass systems of (SrO–B2O3) and (BaO–B2O3) glasses display vibrational bands due to both BO4 and BO3 groups, while Bi2O3–B2O3 glass shows the interference of additional vibrational bands due to BiO6 and BiO3 groups. Photoluminescence spectra of the samples exhibited similar excitation and emission peaks for the three CuO-doped glasses. They are assumed to originate from the excitation of (3 d9 4s3d10) transitions in Cu2+ ions. Gamma irradiation caused some changes in all spectral measurements, and upon inclusion CuO doping no noticeable changes have been identified. Thermal expansion data were analysed and correlated with increasing the amplitude of atomic vibrations, field strength and bond strength of the cations with oxygen.