I. Ardelean

THE STUDY OF COPPER-DOPED B2O3·Bi2O3 GLASS MATRIX BY SPECTROSCOPIC METHODS

Glasses of xCuO · (100-x)[B2O3 · Bi2O3] 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 BiO3, BiO6, BO3 and BO4 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 2B1g→2B2g transition of the of Cu2+ ions in octahedral symmetry with an elongated tetragonal distortion.

STRUCTURAL INVESTIGATIONS OF CuO–B2O3–Bi2O3 GLASSES BY MEANS OF EPR AND FT-IR SPECTROSCOPIES

EPR and FT-IR spectroscopy have been used to investigate the B2O3–Bi2O3 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 Cu2+ ions in axially distorted octahedral environments. No superexchange interaction of Cu2+ 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 [BiO6] polyhedra, tri- and tetra-borate units (BO3, BO4) and its dependence by the copper content.

EPR AND MAGNETIC SUSCEPTIBILITY STUDIES OF COPPER IONS IN THE 2B2O3·Ag2O GLASS MATRIX

Glasses of the xCuO·(100-x)[2B2O3·Ag2O] system, with 0 5 mol% of Cu2+ and Cu+ ionic species. The Curie behavior of magnetic susceptibility indicates the absence of the superexchange interactions in these glasses.