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 ${\mathrm{B}}_2$ ${\mathrm{O}}_3$ (∼723 K) all the way to 1300 K.