New Methods Versus Old Questions: Crystallization Kinetics of S, Se, and Te

Abstract

Using conventional differential scanning calorimetry (DSC) and Flash DSC, we revisited the old question of crystallization kinetics of chalcogens. Together with the appropriate viscosity models and Stokes− Einstein relation, the quantitative results of crystallization kinetics in chalcogenide supercooled liquids were revealed. It showed that the fragilities of S, Se, Te are 126, 67.5, 60, and the maximum crystal growth rates are 9.7 × 10 −3 , 1.3 × 10 −6 , and 0.47 m s −1 at 0.91, 0.94, and 0.86 T m , respectively. Such results not only benefit to understand the fundamental science but also help to design new chalcogenide compositions for applications.

A method to quantify crystallinity in amorphous metal alloys: A differential scanning calorimetry study

“…For example, amorphous silicon is widely used for the fabrication of solar cells and thin film transistors. Amorphous chalcogenides are used as phase-change memory materials [6][7][8], biosensors [9][10][11], and infrared optical fibers [12][13][14]. For the case of amorphous metals, their high hardness, strength and wear resistance, offers the promise of creating a new class of structural materials for applications in diverse areas, including shot peening balls and fine precise polishing media [15], as well as micro gears [16].…”

Fragility of 1D Floppy Materials

“…In addition, for liquid and glassy Se, it has been known that the atomic structure is composed mainly with distorted chain molecules with an estimated atomic number of 10 5 –10 6 at the melting temperature T m (=494 K) . Also, η ( T g / T ) with T g ≈ 310 K, leading to m ≈ 65, has been reproduced . Incidentally, note that throughout the present analyses, the accuracy of m is estimated at about ±5, due to limited temperature ranges of η ( T g / T ) data and so forth.…”

“…[2,26,27] Also, η(T g /T ) with T g % 310 K, leading to m % 65, has been reproduced. [28][29][30][31][32] Incidentally, note that throughout the present analyses, the accuracy of m is estimated at about AE5, due to limited temperature ranges of η(T g /T ) data and so forth. In contrast, the situation for S is complicated.…”

“…In contrast, the situation for S is complicated . The reason is ascribable to the two factors: crystallizable tendency of S 8 ring molecules and existence of the polymerization temperature T λ at 159 °C (=432 K > T m ≈ 390 K), which appears in Figure as the η drop at T g / T ≈ 0.55. It is generally assumed that below and above the temperature, respectively, the liquid consists of S 8 molecules and contains chain molecules with varied atomic numbers; e.g., 10 4 –10 6 at ≈440 K, which are assumed to govern the viscosity of a supercooled state at T g / T ≈ 0.8 .…”

“…In contrast, the situation for S is complicated . The reason is ascribable to the two factors: crystallizable tendency of S 8 ring molecules and existence of the polymerization temperature T λ at 159 °C (=432 K > T m ≈ 390 K), which appears in Figure as the η drop at T g / T ≈ 0.55.…”