Heat of structural transformation at the semiconductor-metal transition in As2Te3 liquid

Internal friction behavior of liquid AsxTe1−x mixtures

“…In the tan U-T curves a notable peak was observed around 505°C in the cooling process and around 506°C in the subsequently heating process. The temperature region of the IF peak during the cooling is from 434°C to 551°C, while during the heating it is from 422°C to 581°C, which are in good agreement with the differential scanning calorimetric results [6].…”

“…With temperature continuously increased, the kinetic energy of the atoms is high enough to readjust the atomic configuration and new chainlike clusters are then constructed. And that this process is reversible, which is suggested by our experiments and differential scanning calorimetric studies [6].…”

“…2 we obtain the activation energy of 5.76 eV and the preexponential factor of 3.2 · 10 À39 s. The pre-exponential factor is greatly higher that of normal liquids, suggesting that the IF behaviors presented in the As-Te melts may not originate from a simple structural relaxation process. On the other hand, previous investigators found a network-chain transformation accompanied by the S-M transition in liquid As-Te mixtures by differential scanning calorimetric, density, EXAFS, conductivity and Hall coefficient measurements [6,7] when temperature is varied. Compared to these results, it can be found that the IF peak position corresponds roughly to that of conductivity and Hall coefficient and its temperature range is in good agreement with that of DSC and density.…”

“…In recent years, considerable attentions have been paid to liquid As chalcogenides because many researches have made the suggestion that ultra-microcrystalline regions or domains of some enhanced ordering in the melts may be present in a variety of glasses [5], and some novel phenomena and abnormal physical properties are gained. For liquid As 40 Te 60 , an exothermic peak appears at 780 K in the differential scanning calorimetric (DSC) curves under cooling, while the density shows a maximum around the corresponding temperature, indicating that a somewhat structural change occurs [6]. The experimental results from extended X-ray absorption fine structure (EXAFS) studies also suggested that there is a structural transformation above 500°C from the network structure composed of threefold coordinated As atoms and twofold coordinated Te atoms to the chain structure [7].…”

Glass Transitions, Semiconductor-Metal Transitions, and Fragilities in Ge−V−Te ( V=As , Sb) Liquid Alloys: The Difference One Element Can Make

“…Figure 8, adapted from the works of Alekseev et al [46] and Nagels et al [47] presents electronic conductivity data in Arrhenius form for a variety of chalcogenides as they pass from low temperature semiconducting states to high temperature "weak metal" states (at the Mott minimum metallic conductivity, ~ 10 3 Ω -1 cm -1 , through a maximum in the apparent activation energy (Figure 8a)). The transition occurs far above the melting point of 641 K [48] for As 2 Se 3 , but when Se is replaced by Te the density anomaly, with extremum α(min), occurs at 780 K, much closer to T m (640K) [49]. Finally, when the more metallic bismuth replaces antimony, the liquid Bi 2 Te 3 is already metallic at its 857 K [50] melting point (see Fig.…”