Lattice vibrations in noncrystalline solids (Technical Report) | OSTI.GOV

Technical Report · Wed Aug 01 04:00:00 UTC 1973

The specific heat of noncrystalline solids differs from that predicted by the Debye model by amounts much larger than is known for crystalline solids. This deviation is most pronounced at temperatures below 1 deg K. Near 0.1 deg K. the experimental specific heat approaches a linear temperature dependence and is up to 30 times larger than predicted by the Debye model. This paper describes Brillouin scattering experiments, and also measurements of the thermal conductivity in thin glass fibers. This work is aimed at elucidating the nature of the excitations responsible for this large specific heat. It is concluded that Debye phonons have sufficiently long lifetimes to be considered as good normal modes in noncrystalline solids and also that these phonons are the main carriers of heat at low temperatures. (11 figures. 29 references) (auth)