Lithium borosilicate glasses containing transition metal ions have
been the subject of an increasing academic and technological interest.
These glasses find a wide range of applications such as glass fibers,
optical lenses, as electrodes, for radioactive waste immobilization, in
hermetic sealing of metallic and ceramic materials and as glass planar
optical waveguides fabricated by ion exchange [1–4]. The addition of
heavy metal oxides like PbO and Bi2O3 makes these glasses more
denser, increases the refractive index and makes the glasses to exhibit
non-linear optical effects since these oxides posses high electrical polarizability.
Bi ions normally exist in Bi3+ state; however these ions
also subsist in Bi+, Bi4+ and Bi5+ states in different hosts according
to their fabricating technique, environmental atmosphere and temperature
and local structure [5]. Earlier, it was also reported that
Bi5+ and Bi+ ions do exhibit NIR emission with meta center at
about 1200 nm with higher life times in the glass matrices [6,7]. In
view of these factors, the addition of Bi2O3 widens the range of applications
of these glasses in optical and optoelectronic devices such as ultrafast switches, infrared windows, optical isolators, thermal and
mechanical sensors [8–10].