Filtern
Erscheinungsjahr
- 2006 (1)
Dokumenttyp
Sprache
- Englisch (1)
Referierte Publikation
- nein (1)
Schlagworte
- Struktur (1) (entfernen)
The structure of 50PbO-xB2O3-(50-x)P2O5 glasses with x=0-25 mol% B2O3 was refined by Raman and 11B MQMAS NMR. The analysis of Raman spectra, using the concentration step of 2 mol% B2O3 within the range of 0-12 mol% B2O3, showed that the evolution of changes in the type of oxygen bridges can be observed from the Raman bands within the range of 600-800 cm-1. 11B MQMAS NMR spectra of glasses with x=15, 20 and 25 mol% B2O3 revealed the presence of two BO4 sites in these glasses. The first site B1O4, characterised by the chemical shift of d=-3·8 (-3·4) ppm, was assigned to tetrahedral B(OP)4 structural units. Within the concentration range x=15-25 mol% B2O3, the site B1O4 is gradually replaced by the site B2O4 with the chemical shift of d=-1·8 (-1·1) ppm. This second site was assigned to the presence of B(OP)3(OB) units in which the central boron atom is linked to three PO4 groups and one BO3 group.