Studies on Optical Absorption Spectra of VO²⁺ Ions in PbO-B₂O₃ and R₂O-PbO-B₂O₃ (R=K or Na) Glasses and Bonding Mode of Pb Atoms in these Glasses

Abstract

The optical absorption spectra of VO²⁺ ions dissolved in PbO-B₂O₃ and R₂O-PbO-B₂O₃ glasses (R=K or Na) have been measured. By using the spectral results, the bonding mode of Pb in the glasses has been discussed. Judging from the dependence of peak position for B₂*-E_π* transition on the glass composition, it is suggested that although Pb behaves as a network modifier in the glasses, a part of Pb contributes to the formation of glass network. This relation is discussed on the basis of the relation between the peak wave number and ratio of four-coordinated B atoms to the total B atoms (N_4B). On the assumption that the Pb ratio used in the formation of the glass network is α(x-0.2) in xPb(1-x)B₂O₃ glasses and (x+y-0.2) in xR₂OyPbO(1-x-y)B₂O₃ glasses, the value of α is calculated to be 2.04.