ELASTIC PROPERTIES OF AMORPHOUS SOLIDS BELOW 100-K

We have performed a survey of the available literature on the speed of sound at temperatures above 5 K in amorphous solids. We have compared the slope, beta, of the linear variation in the speed of sound at the se temperatures with the temperature independent internal friction bel ow 10 K, Q(0)(-1), and find that, empirically, beta = 0.5 Q(0)(-1)/K. This suggests that the low temperature properties of amorphous solids are connected with their universal behavior at higher temperatures. Ad ditionally, we have extended our survey to crystals with glass-like pr operties as well as to quasicrystals. We find that the same relationsh ip that exists in amorphous solids between Q(0)(-1) and beta exists in these solids as well. A model to explain this very general empirical relation does not seem to exist.