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EPR and FT-IR spectroscopy have been used to investigate the B 2 O 3– Bi 2 O 3 glass matrix containing CuO in order to obtain more information about the local structure of these glasses. The EPR absorption spectra revealed the presence in the glass structure of the Cu 2+ ions in axially distorted octahedral environments. No superexchange interaction of Cu 2+ was detected. In the samples with x≥5 mol%, mixed valence states of copper ions were revealed. The FT-IR measurements indicate the presence in the glass structure of the distorted [ BiO 6] polyhedra, tri- and tetra-borate units ( BO 3, BO 4) and its dependence by the copper content.

Glasses of x CuO · (100-x)[ B 2 O 3 · Bi 2 O 3] systems with 0≤x≤50 mol% were prepared and investigated by means of FT-IR, Raman and optical absorption spectroscopies. Complex network structures mainly built by BiO 3, BiO 6, BO 3 and BO 4 units were revealed for these glasses by means of FT-IR measurements. Similar structures were evidenced by means of Raman spectroscopy and additional new structural groups were detected in the glass structures, i.e. pyroborate, chain and ring type metaborate groups. The influence of copper-ion content (x) on the short-range order structure evolution was investigated. The optical absorption spectra for all glass samples present a single asymmetric band which corresponds to a 2 B 1g→2 B 2g transition of the of Cu 2+ ions in octahedral symmetry with an elongated tetragonal distortion.