Shear waves through the glass-liquid transformation

Abstract

The temperature dependence of hypersonic longitudinal and transverse sound waves in ``strong'' (${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$) and ``fragile'' [${\mathrm{Ca}}_{0.4}$${\mathrm{K}}_{0.6}$(${\mathrm{NO}}_{3}$${)}_{4}$] glass-forming systems have been probed using Brillouin scattering. In the latter material the transverse modes become masked by a central component in the spectrum which broadens as the temperature is raised through the liquidus temperature; in ${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$, on the other hand, well-defined (undamped) transverse modes are observed above the melting temperature of crystalline ${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$ (\ensuremath{\sim}723 K) all the way to 1300 K.