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    STUDIA PHYSICA - Ediţia nr.SPECIAL ISSUE din 2001  
         
  Articol:   STUDIES OF BORATE VANADATE GLASSES USING RAMAN AND IR SPECTROSCOPY.

Autori:  D. MANIU, T. ILIESCU, I. ARDELEAN, IOAN BRATU, C. DEM.
 
       
         
  Rezumat:  Raman and IR spectra of xV2O5.(1-x)B2O3 glasses (with 0.05  x  0.8) have been measured and analysed. The band characteristic to boroxol groups (806 cm-1) is present only at very low V2O5 content. This band has small intensity and disappears when V2O5 content increases, while the Raman bands assigned to diborate groups and isolated BO4 units are present in all spectra. The presence of V2O5 in B2O3 glasses determines the appearance of four-fold coordinated boron atom in diborate groups and isolated BO4 units. In this glasses chain type metaborate groups are also identified. For high V2O5 content, the intensity of the band centered at 993 cm-1 does not decrease as that from 1022 cm-1 (both assigned to diborate groups). Therefore, we presume that at 993 cm-1 are overlap two bands: one is characteristic to diborate groups and the other one to vanadate structure. IR spectra reveal same changes as in Raman spectra. For samples having x  0.6 a peak characteristic to V2O5 appears. This is an indication that vanadate structure was forming. Therefore, we conclude that the vanadium oxide acts as network modifier in these glasses for 0.05  x  0.5. For 0.6  x  0.8 vanadium oxide acts as glass forming.  
         
     
         
         
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