H. Kumar

Calorimetric studies of glass transition phenomenon in glassy Se80?xTe20Snx alloys

Glass transition kinetics has been studied in a glassy Se80?xTe20Snx (0 ?x ?10) system. Differential scanning calorimetry (DSC)?runs were taken at four different heating rates (5, 10, 15 and 20?K?min?1) for this purpose. The heating rate dependence of the glass transition temperature (Tg) has been studied using different non-isothermal methods. The activation energy of glass transition (Eg) has been evaluated using Kissingers relation and the theory of Moynihan. The composition dependence of Tg and Eg has also been discussed.

Calorimetric studies of thermal crystallization in glassy Se80−xTe20Snx (0⩽x⩽10) alloys

This paper reports a calorimetric study of the crystallization kinetics in glassy Se80−xTe20Snx (0≤x≤10) alloys in terms of kinetic parameters of crystallization (crystallization temperature Tc, activation energy of crystallization Ec and order parameter n) and thermodynamic parameters of crystallization (enthalpy of crystallization Hc and the entropy of crystallization Sc).

Thermal characterization of Se 78 − x Te 20 Sn 2 Pb x (0 ≤ x ≤ 6) glassies for phase change optical recording technique

New multi-component glasses of Se78 − xTe20Sn2Pbx (0 ≤ x ≤ 6) system have been synthesized using melt-quench technique. Differential Scanning Calorimetric measurements are performed at different heating rates under non-isothermal conditions to study the glass transition kinetics of prepared chalcogenide glass. Different kinetic parameters such as the activation energy of glass transition, thermal stability, glass forming ability etc have been determined. The composition dependence of kinetic parameters of glass transition is also discussed.

Composition dependence of specific heat in Se 80 − x Te 20 Sn x chalcogenide glasses

Differential Scanning Calorimetry (DSC) is performed at different heating rates under non-isothermal conditions to study the specific heat studies of glassy Se80 − xTe20Snx (0 ≤ x ≤ 10) alloys. An extremely large increase in the specific heat values has been observed at the glass transition temperature. It has also been found that the values of Cp below glass transition temperature (Cpg) and after glass transition (Cpe) are highly composition dependent. This indicates that the Sn additive used in the present study influences the structure of the glassy Se80Te20 alloy. The results show that Cp values reveal local extrema in Se-Te-Sn glassy system at x = 4 and x = 8. The composition dependence of both parameters (Cpe and Cpg) has been explained in terms of the glassy structure of Se-Te-Sn system.

Calorimetric study of specific heat in glassy Se–Te–Sn–Bi system using MDSC technique: effect of Bi incorporation

Bismuth has historical significance as a modifier in chalcogenide glasses due to the p- to n-type transition at a particular composition of definite glassy systems after its incorporation. We have synthesized some new quaternary glasses using Bi as a modifier in ternary Se78Te20Sn2 alloy as parent glass in light of this information. Modulated differential scanning calorimetry measurements have been made on glassy Se78− x Te20Sn2Bi x (0 ≤ x ≤ 6) alloys for specific heat studies. We have observed an expected enormously large increase in the specific heat values in the glass transition region. The composition dependence of specific heat values above the glass transition temperature (Cpe ) and below the glass transition (Cpg ) is also discussed in this article.

Effect of lithium ion irradiation on the glass transition kinetics of Se98In2 chalcogenide glass

Glass transition kinetics in glassy Se98In2 alloy is studied using differential scanning calorimetry under two different conditions. In the first condition, normal samples of the present glass are used. In the second condition, the ion-irradiated samples are used to see the effect of ionic irradiation on the glass transition kinetics of present alloy. For this high energetic beam (50 MeV) of lithium ions is used. After the ion irradiation on the glass, drastic changes in kinetic parameters of glass transition are observed. The results are explained by the model developed by Kastner et al. (Valence-alternation model for localized gap states in lone-pair semiconductors, Phys. Rev. Lett. 37 (1976), pp. 1504–1507).

Role of Bi incorporation on glass transition kinetics in glassy Se78Te20Sn2 alloy

ABSTRACT In this communication, we report the results of calorimetric measurements on the samples of recently synthesized multi-component glassy alloys of Se78−xTe20Sn2Bix (0 ≤ x ≤ 6) system. For calorimetric study of glass transition kinetics, differential scanning calorimetry (DSC) technique has been used in non-isothermal mode. Peak glass transition temperature (Tg) is determined using the DSC scans. Kinetic parameters A and B of glass transition are determined using heating rate dependence of Tg. Activation energy of glass transition (Eg) has been calculated using Moynihan and Kissinger methods. Glass-forming ability and thermal stability are also determined using Hurby and Saad–Poulin relations, respectively.

Effect of lithium-ion irradiation on the crystallization kinetics of glassy Se98In2

Differential scanning calorimetry (DSC) has been used to study the crystallization kinetics of glassy Se98In2 both before and after irradiation of the alloy with high-energy (50 MeV) lithium ions. After the ion-irradiation, significant changes in the kinetic parameters of crystallization of the glass were observed. The results are explained in terms of a model involving irradiation-induced defects.