Nephelauxetic effect of low phonon antimony oxide glass in absorption and photoluminescence of rare-earth ions

An antimony oxide based monolithic glass with very high Sb2O3 content (70 mol%) in the system K2O-B2O3-Sb2O3 (KBS) has been prepared for the first time. Its phonon energy (602 cm(-1)), evaluated by infrared reflection spectroscopy, is found to be very close to that of fluoride glasses (500-600 cm(-1)). After doping with different rare-earth ions, their UV-vis absorption and photoluminescence properties have been explored, compared with those observed in other hosts and justified with quantitative calculation of nephelauxetic parameter and covalent bonding characteristics. It is been proposed that tunable laser or new color visible light sources may be obtained by controlling these fundamental properties of the glass host. The results also suggest that KBS glass may be used as hosts in the place of fluoride glasses. The Judd-Ofelt parameters, Omega(t=2,4.6) for Nd3+, Ho3+, and Er3+ doped in KBS glass have been evaluated and compared with other glasses. It is established that Omega(t=2) value follow a direct relationship with covalent character of the hosts which not only supports the above calculation but also provides a generalized evidence for the sensitivity of this parameter to their bonding characteristics. (C) 2011 Elsevier B.V. All rights reserved.