Constraints in glasses Acoustic attenuation in Ge_xS_1-x and Ge_xSe_1-x glasses

Abstract

Measurements of acoustic attenuation and relative acoustic velocity at 550 kHz were taken between 4·2 and 200 K in Ge_xS_1-x and Ge_xSe_1-x glasses, for x = 0·2, 0·33 and 0·4. For x = 0·2 and 0·33, glasses in both systems show a low-temperature peak in the attenuation, together with an increasing attenuation at higher temperatures as the glass-transition temperature is approached. With x = 0·4 the loss in both glasses is very much smaller at all temperatures. These results are interpreted in terms of constraints acting on the glass-forming network.

The velocity decreases with increasing temperature in all the glasses, so that GeS₂ and GeSe₂ differ from other tetrahedrally coordinated glases in this respect.