Abstract
In this work, bismuth-niobium based sodium borate glass was modified by introducing Ag2O additives according to the formula 100 wt% {60 mol% B2O3 + 17.5 mol% Na2O + 17.5 Bi2O3 + 5 mol%Nb2O5} + x wt% Ag2O, where x = 0, 1.5, 3.0, 4.5, and 6.0. Glass samples were prepared by traditional melt quenching method, and silver oxide was incorporated by weight addition. X-ray diffraction analysis revealed the amorphous nature of the studied materials and that the addition of Ag2O didn't affect structural phases. Vibrational transitions showed cross-linking between BO3, BO4, and BiO3 structural groups, meanwhile the Na+, NbO6, and BiO6, in addition to the Ag2+ occupy the interstitial spaces. Furthermore, the study shows a transition of Bi2O3 from acting as a glass network modifier BiO6 to a glass network former BiO3. Study of the electronic transitions showed that the optical absorption edge is located around 505 nm. Furthermore, the addition of Ag2O caused a slight decrease in the value of Urbach energy which means an increase in the structural ordering, that may be assigned to the conversion of BO4 to BO3.