Structural studies of iron doped B₂O₃•0.7PbO•0.3Ag₂O glasses by FT-IR and Raman spectroscopies

Abstract

Glasses from xFe₂O₃·(100-x)[3B₂O₃·0.7PbO·0.3Ag₂O] system, with 0 ≤ x ≤ 20 mol.%, were prepared and investigated by means of two complementary spectroscopic methods, FT-IR absorption and Raman scattering in order to obtain information concerning the network structure. Both FT-IR and Raman spectroscopic techniques have revealed changes in the local structure of the glasses when the composition is modified. The iron ions modifier role is pointed out by the shape of the recorded spectra, changed with increasing the Fe₂O₃ content. The influence of a gradual addition of the iron oxide on the local structure of silver lead borate based glasses has been studied. The FT-IR data indicate the presence of the BO₃ and BO₄ structural units in the glasses, the network structure being mainly built by: di-, tri-, tetra-, penta- and orthoborate groups. The characteristic bands of the different structural groups evidenced in these glasses were identified and quantitatively analyzed after increasing the Fe₂O₃ content. The Fe₂O₃ content dependence of Ar (A₄/A₃) ratio (where the values A₄ and A₃ reflect the relative amount of tetra-, respectively tri-coordinated boron atoms) was studied. In addition, characteristic vibrational modes of bonds from iron, lead and silver oxides were detected in the FT-IR spectra. Raman data is in accordance with the FT-IR results and complete them. Using Raman scattering, we detected new structural groups as pyro-, ditri- and dipenta-borate groups, indicating changes in the structure of our glasses after Fe₂O₃ addition