BRILLOUIN-SCATTERING STUDIES OF K2SI4O9 GLASS AND MELT UP TO 1000-DEGREES-C

The Brillouin-scattering technique has been used with glass plate samples and with glass sandwich assemblies to measure the acoustic velocities of K2Si4O9 glass as a function of temperature up to 1000-degrees-C. Results differ from those of the sodium silicate glass reported earlier in that the turning points of the velocity versus temperature curves for the potassium silicate glass are found not only at the strain point (466-degrees-C) but also at the softening point (720-degrees-C). Combined with the results of the 90-degrees platelet- and 180-degrees back-scattering geometry measurements, the refractive index n and equation of state of the glass and melt as a function of temperature were also determined.