Composition dependence of absorption edge energy of borate glasses containing a large amount of Bi₂O₃

Abstract

Absorption edge energy has been studied in Bi₂O₃–B₂O₃, and (Li₂O, Na₂O, K₂O, CaO, BaO, ZnO, Ga₂O₃ and Nb₂O₅)–Bi₂O₃–B₂O₃ glasses containing a large amount of Bi₂O₃. It was found that the absorption edge energy obeyed Duffy’s theoretical basicity formula, that is, the additivity rule with glass composition. The additivity factor depended on electronegativity of each constituent atom, except bismuth. The additivity factor of Bi₂O₃ was much smaller than that expected from electronegativity. The small value of additivity factor of Bi₂O₃ was discussed on the basis of Bi–O–Bi bond formation.