Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7900135 | Journal of Non-Crystalline Solids | 2018 | 12 Pages |
Abstract
Raman spectra at 298â¯K of the SiO4 symmetric stretch region (800-1200â¯cmâ1) for low alkali (M) silicate glasses (5 and 10â¯mol% M2O, for Mâ¯=â¯Cs, K) yield intense well-resolved Q3 peaks at ~1100â¯cmâ1 with mostly Lorentzian character, in contrast to previous Gaussian fits for silicate glasses. The spectra of 5â¯mol% Na and Li glasses show an additional Q3 peak. It results from close approach of alkalis (M) to bridging oxygen (BO) which splits the Q3 band into two peaks. All linewidths (FWHM) of fitted Q1, Q2 and Q3 species peaks are similar (~35-55â¯cmâ1) at 298â¯K for all the above glasses. The Q3 species FWHM of 5 and 10â¯mol% Cs2O silicate glasses show a T dependence similar to those of crystal silicate spectra: both increase by 35-45â¯cmâ1 from 298â¯K to 1200â¯K. The T dependence of the FWHM of these Lorentzian dominated peaks are consistent with theory. The more complex spectra of the 30â¯mol% K2O and 50â¯mol% Na2O glass spectra are then readily fit with two or three Q2 or Q3 peaks, constraining the % Lorentzian character of all peaks from the fit to the resolved peak in those spectra. The 50â¯mol% Na2O spectrum shows that Q3â¯>â¯Q1, indicating ~4.5â¯mol% free oxygen in the glass, a value in good agreement with previous 29Si NMR and O 1s XPS results. Lorentzian/Gaussian lineshapes now need to be considered for many more silicate glass/melt Raman spectra.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
G. Michael Bancroft, H. Wayne Nesbitt, Grant S. Henderson, Cedrick O'Shaughnessy, Anthony C. Withers, Daniel R. Neuville,