Raman study of B2O3-SrO-CuO glasses

The influence of copper oxide (CuO) content on the structure of 3B(2)O(3).SrO glass was investigated by means of Raman spectroscopy. For the sample without CuO, the Raman spectrum indicates a structure with majority pentaborate groups. At high wavenumbers, there is a broad and intense band probably due to fluorescence induced by strontium. The addition of CuO in 3B(2)O(3).SrO glass causes changes in the features of the Raman spectra. When CuO content rises the Raman band corresponding to boroxol units becomes higher than the one characteristic to pentaborate groups. The fluorescence band decreases in intensity and vanishes for x greater than or equal to 0.03. The structure of glasses with low CuO content contains pentaborate groups, boroxol rings, orthoborate groups, chain-type metaborate groups and diborate groups. For high CuO content the number of pentaborate groups decreases, orthoborate and diborate groups disappear and pyroborate groups are formed. Therefore, we conclude that the copper ions act as network modifier in these glasses. (C) 2002 Elsevier Science B.V. All rights reserved.