Brillouin and Raman spectroscopies were used to investigate the structure of xAl2O3. (72.08-x) SiO2. 14.81 Na 2O.11.85 MgO.1.26 Eu2O3 (x=0, 2.96, 5.92, 8.88, 14.81 mol%; and yNa2O. (83.93-y) SiO2. 2-96 Al 2O3.11.85 MgO.1.26 Eu2O3 (y=9.86, 14.81, 19.73, 24.67 mol%) glasses. The depolymerisation (polymerisation) of the Eu3+ doped soda magnesia aluminosilicate (EDSMAS) glass is mainly characterised by the presence of nonbridging (bridging) oxygens and three (four) member silicate and aluminosilicate rings. The aluminium formers entering the glass recover Si-O-Si bridges by attracting charge balancing modifiers from depolymerised SiO4 network. In this way the (Si,Al)4 rather than (Si,Al)3 membered rings are formed, i.e. the overall structure becomes more polymerised rather than fragmented. This is supported by the glass elastic constants and moduli as measured by Brillouin spectroscopy. Concurrent increasing polarisability deduced from the enhanced Poisson's ratio is mostly due to the appearance of AlO4 tetrahedral groups weakly bound to sodium ions. The sodium modifier ions substituting for silicon atoms depolymerise the glass causing the formation of distinct Q3 and Q2 species and the rapid increase in the number of three member rings. However, the overall glass structure becomes less compressible in the volumetric sense.
|Number of pages||7|
|Journal||Physics and Chemistry of Glasses|
|Publication status||Published - Jun 1 2004|
ASJC Scopus subject areas
- Ceramics and Composites
- Physical and Theoretical Chemistry