Glass transition and crystallization kinetics of Sb_14.5As_29.5Se_53.5Te_2.5 amorphous solid

Abstract

Original PaperGlass transition and crystallization kinetics of Sb 14.5 As 29.5 Se 53.5 Te 2.5 amorphous solidThe crystallization kinetics of the quaternary Sb 14.5 As 29.5 Se 53.5 Te 2.5 glassy alloy was studied under nonisothermal conditions. The method was applied to the experimental data obtained by differential scanning calorimetry (DSC), using continuous-heating techniques. In addition, two approaches are used to analyze the dependence of glass transition temperature (T g ) on the heating rate (β). One is empirical linear relationship between (T g ) and ln (β). The other approach is the use of straight line 2 g ln (T /b) vs. 1/T g for evaluation of the activation energy for glass transition. The phases at which the alloy crystallizes after the thermal process have been identified by X-ray diffraction. The diffractogram of the transformed material shows the presence of some crystallites of As, SbTe, AsSb, As 2 Se 3 , Sb 2 Se 3 and AsSe 5 Te 5 in the residual amorphous matrix.ampoule was shaken several times to maintain their uniformity. Finally, the ampoule was quenched into ice cooled water to avoid crystallization.The amorphous state of the material was confirmed by a diffractometric X-ray scan (Philips diffractometer 1710) using Cu as target and Ni as filter (λ = 1.542 Å). Energy dispersive X-ray spectroscopy (Link analytical EDS) was used to measure the elemental composition and indicates that the investigated composition is correct up to ±0.2 at%.The calorimetric measurements were carried out using differential scanning calorimeter Shimadzu 50 with an accuracy of 0.1 K, keeping a constant flow of nitrogen to extract the gases generated during the crystallization reactions, which, is a characteristic of chalcogenide materials. The calorimeter was calibrated, for each heating rate, using the well-known melting temperatures and melting enthalpies of zinc and indium supplied with the instrument [12]. 20 mg powdered samples, crimped into aluminum pans and scanned at continuous heating rates (β = 2.5, 5, 10, 15, 20, 25 and 30 K min -1 ). The value of the glass transition temperature, T g , the crystallization extrapolated onset, T c and the crystallization peak temperature, T p , were determined with accuracy ±1 K by using the microprocessor of the thermal analyzer.The fraction, χ, crystallized at a given temperature, T, is given by χ = A T /A, where A is the total area of the exotherm between the temperature, T i , where crystallization is just beginning and temperature, T f , where the crystallization is completed, A T is the area between T i and T, as shown in Fig. 1.

Thermal stability of Ge–As–Te–In glasses

“…Values of E g for Ge 15 As 20 Te 65−x In x (x = 0, 3, and 6 at.%) glasses were listed in Table 2. Values of E g for the Ge 15 As 20 Te 65−x In x glasses lie within the observed values for chalcogenide glasses [32][33][34]. As shown in this table E g increases with the increase of In content.…”

Effect of Te additions on the glass transition and crystallization kinetics of (Sb15As30Se55)100−xTex amorphous solids

“…(8) and taking the logarithm of the quoted equation leads to an expression that in the range of values of y = E/RT, 25 ≤ y ≤ 55, can be fitted very satisfactorily by a linear approximation (an additional assumption) yielding [20] ln[e −y y −2 (1 − 2y −1 )] ∼ = −5.304 − 1.052y (9) Substituting into Eq. (8)…”

“…The study of crystallization kinetics in amorphous materials by the DSC method has been widely discussed in the literature [5][6][7][8][9][10]. There are large varieties of theoretical models and functions proposed to explain the crystallization kinetics.…”

Thermal features and physical properties of sulfur modified barium vanadate glasses

“…Furthermore, the activation energy of glass transition, the activation energy for crystallization, the frequency factor and the kinetic exponent n can be evaluated using these equations [25,30];…”