Enthalpic structural relaxation in Te-Se glassy system

Crystallization mechanisms occurring in the Se–Te glassy system

“…Considering the abovementioned trend, together with the fact that for pure Se both activation energies are again similar, a sharp transition in the DE quantity may be expected around the Se 95 Te 5 composition. This hypothesis is further supported by recent structural relaxation studies [24,25], which revealed a marked sharp increase in the non-exponentiality parameter within the 0-10 at% Te compositional range (see Fig. 10).…”

“…Bearing the above mentioned in mind, it leaves the joint effect of the Se-Te chain length and the strength/quantity of the van der Waals forces interconnecting the neighboring chains as a possible reason for the anomalous behavior reported in the current article. In particular, the high degree of cooperativity and interlinking expected for the Se 95 Te 5 glass (based on the compositional dependence of relaxation non-exponentiality [24,25]) may be responsible for slower release of stress and strain accumulated in the material during the hyperquenched glass formation, which in consequence leads to irreversible formation of microstructural defects. For a small number of large cooperatively relaxing clusters the stress would not be distributed uniformly and the formation of defects could then be localized at an interface between structurally diverse segments.…”

Crystallization kinetics in Se–Te glassy system

“…However, during these experiments it was found that the glass transition and crystallization temperatures of the studied glasses are too close and that for higher heating rates the large relaxation overshoot partially overlaps the crystallization peak. Complex structural relaxation study [16] of the prepared glasses showed that addition of tellurium atoms into the selenium matrix results in decreased spatial heterogeneity (probably caused by increased tendency of tellurium chains to form stronger interchain van der Waals type bonds which may increase segmental cooperativity) accompanied by a narrower distribution of relaxation times. In practice, when the raw glasses are prepared by a rapid cooling of the original melt, the resulting material is highly nonequilibrium, the consequence of which is fast formation of a deeply relaxed glass.…”

Glass transition kinetics measured by fast scanning calorimetry

“…22°C. In our previous studies, e.g., [15,28,29], we have shown that even in practice the above-described theoretical behavior holds perfectly over several orders of magnitude of the q ? change (the q ?…”