Abstract
The optical absorption spectra of the glasses with composition xBi2O3·(30 − x)R2O·70B2O3 (R˭Li, Na, K) and xBi2O3·(70 − x)B2O3·30Li2O (0 ≤ x ≤ 20) have been recorded in the wavelength range 350–650 nm. The glass samples were prepared by the normal melt–quench technique. The fundamental absorption edge for all the series of glasses is analyzed using the theory of Davis and Mott. The position of absorption edges and the values of optical band gap are dependent on the mol% of Bi2O3. The absorption in these glasses is associated with indirect transitions. The values of Urbach's energy and band tailing parameters are reported. The two photon absorption coefficient, β, in these glasses has also been estimated from the optical band gap and its value ranges from 1.3 to 11.6 cm/GW. The relationship between β and glass composition has also been discussed in terms of the electronic structure of the glass system.
Acknowledgements
This work was supported by CSIR, UGC and DST (FIST scheme), New Delhi, India for providing financial support.