Brillouin-scattering studies of a sodium silicate glass in solid and melt conditions at temperatures up to 1000 °C

Abstract

By using the sapphire-glass-sapphire sandwich-glass-assemblage Brillouin-scattering technique, the velocities of shear and longitudinal modes of a sodium silicate glass have been measured as a function of temperature up to 1000 \ifmmode^\circ\else\textdegree\fi{}C. A turning point was found at the strain point (494 \ifmmode^\circ\else\textdegree\fi{}C) but not at the softening point (720 \ifmmode^\circ\else\textdegree\fi{}C). Combined with the results of the 90\ifmmode^\circ\else\textdegree\fi{}- and 180\ifmmode^\circ\else\textdegree\fi{}-scattering-geometry measurements, the refractive index (n) of the glass as a function of temperature was also determined. As a result, independent criteria for both the strain and softening points are suggested.