Abstract. Glasses from xFe 2 O 3 ·(100-x)[3B 2 O 3 ·0.7PbO·0.3Ag 2 O] 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 Fe 2 O 3 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 BO 3 and BO 4 structural units in the glasses, the network structure being mainly built by: di-, tri-, tetra-, penta- and ortho- borate groups. The characteristic bands of the different structural groups evidenced in these glasses were identified and quantitatively analyzed after increasing the Fe 2 O 3 content. The Fe 2 O 3 content dependence of A r (A 4 /A 3 ) ratio (where the values A 4 and A 3 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 Fe 2 O 3 addition.

Keywords: silver-lead-borate glasses, iron ions, FT-IR, Raman spectra, structure.

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