Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7902608 | Journal of Non-Crystalline Solids | 2014 | 6 Pages |
Abstract
Container-less levitation techniques and CO2-laser heating were used to prepare a series of silicate glasses along the compositional join (1 â X)(0.5Ca-0.5 Mg)O-XSiO2 with X ranging between 0.50 and 0.27; thus reaching compositions beyond the orthosilicate limit (X = 0.33). Polarized and depolarized Raman spectra measured at ambient conditions for all these glasses show systematic and smooth band intensity changes with composition. Qi-species analysis of the isotropic Raman spectra shows the presence a) of bridging oxygens in all glasses studied with silica mole fractions down to X = 0.33 and b) of free oxygen at all compositions. Beyond the X = 0.33 limit, the connectivity between the SiO4 tetrahedra decreases drastically and the corresponding glass structures are characterized by isolated negatively charged “tetrahedral” SiO44 â and O2 â anions with M2 + (M = Mg, Ca) as counter cations, held together by pure Coulombic (ionic) interactions. The Boson peak appears in the low-frequency range 70-90 cmâ 1 and its polarization characteristics and frequency shifts with glass composition are pointed out and discussed.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
A. Retsinas, A.G. Kalampounias, G.N. Papatheodorou,