Slow structural relaxation in liquid Te–Se mixtures

We have measured the sound attenuation, a, in liquid Te50Se50 at 20, 32 and 43 MHz and Te70Se30 at 32 MHz in a wide temperature and pressure range and have found three distinct absorption mechanisms. Near the melting point, a decreases rapidly with increasing temperature, which may be due to conformational changes within the chain molecules. At intermediate temperatures a sharp absorption peak appears and its position shifts to higher temperature with increasing frequency, while at high temperatures around 820 C a broad peak appears irrespective of the frequency. We discuss the origin of these absorption peaks in connection with the semiconductor–metal transition. 2002 Elsevier Science B.V. All rights reserved.