Summary:
Amorphous materials have low temperature properties quite different from those observed in crystals. Their specific heat contains an excess below about 1 K which varies linearly with thetemperature T. Their phonon thermal conductivity varies as T2. Their acoustic behaviour is also quite characteristic : the velocity first increases logarithmically with temperature and the absorption is saturable. All these properties are believed to be intrinsic to the amorphous state. They have been observed in insulating glasses [1]. In amorphous metals the observed behaviour is similar; the main differences can be attributed to the presence of conduction electrons [2]. Most of the low temperatures properties of semiconducting glasses and also amorphous polymers are similar to those of insulating glasses [1]. All these particular features are well explained in the framework of the two-level system (TLS) theory which assumes the existence of a particle moving in a double-well potential by quantum-mechanical tunnelling [1]

Format:
Pages : 6
Size: 940 kb
Author : P. Doussineau and W. Schön


Download:
Acoustic propagation in an epoxy resin at very low temperatures

 

Free Epoxy Ebooks page 1, 2, 3, 4, 5