Introduction
Bi2O3 is an interesting non-conventional oxide which exhibits
wider glass-forming ability with either SiO2, B2O3 or P2O5 to form stable glasses with variable applications. These glasses possess some of the highest densities, refractive indices and coefficients for second and third harmonic generations [1,2], Also, crystallized
Bi2O3 glasses containing rare-earth or transition metal ions have proven to be of special applications to laser host, tunable waveguide, tunable fiber grating [3,4]. Due to the high density and good
transparency of Bi2O3-glasses, they are useful for radiation-shielding and scintillation counters [5]. Extended studies on the constitution of bismuth borate glasses [6–10] and bismuth silicate glasses
[11–13] by infrared, and Raman spectroscopy, have indicated that Bi3+ ions can participate both as network modifier and as network former in the form of pyramidal BiO3 and/or octahedral BiO6 units
and the ratio of each unit depends on the composition of the glass.