The effect of Bi content on the thermal stability and crystallization of Se-Te chalcogenide glass (original) (raw)
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On the glass transition phenomenon in Se–Te and Se–Ge based ternary chalcogenide glasses
Physica B: Condensed Matter, 2009
The present paper reviews the results of non-isothermal differential scanning calorimetry (DSC) measurements on some ternary glassy systems of Se-Te and Se-Ge chalcogenide alloys for evaluation of activation of glass transition. The activation energy of glass transition (E g) is calculated using Kissinger's relation, which is basically derived for amorphous to crystalline phase transition. The results show that E g values obtained from Kissinger's relation are in good agreement with the E g values which are obtained using Moynihan's relation based on the concept of thermal relaxation. This proves the applicability of Kissinger's relation for determination of activation energy of glass transition.
Ternary Se 90 Te 10 À x Sn x (x ¼2, 4, 6, and 8) chalcogenide glassy alloys have been prepared by melt quenching technique. Various crystallization parameters, such as onset (T c) and peak (T p) crystallization temperatures, activation energy of crystallization (E c) and Avrami exponent (n) have been determined for these alloys. T c and T p have been determined directly from the non-isothermal differential scanning calorimeter (DSC) thermograms. The value of E c has been calculated from the variation of both T c and T p with the heating rate (β) according to Kissinger, Takhor, Augis–Bennett and Ozawa models while Augis– Bennett method has been used to deduce the value of n for the studied samples. The obtained values of the crystallization parameters have been correlated with the character and the energy of the chemical bonds through the calculation of the heteronuclear bond energies of the constituent atoms using Pauling principle. In addition to that, Tichy–Ticha model was used to estimate the mean bond energy of the average cross-linking per atom 〈E cl 〉, the average bond energy per atom of the remaining matrix 〈E rm 〉, and the overall mean bond energy 〈E〉 of the studied glasses. Results reveal that both of T c and T p decreases with increases Sn content. This is may be attributed to the decreasing in the overall mean bond energy 〈E〉. Besides, the plot of E c (and also T g) against 〈E〉 was found to be non linear, which contradicts the well known linear correlation between E c and T g with 〈E〉 as suggested by Tichy–Ticha model. This discrepancy may be due to the fact that the Tichy–Ticha linear correlation model was based on the assumption of covalent glassy network, while in the present glassy alloys, Se–Te binary doped with heavy elements such as Sn exhibit iono-covalent bonding. The calculated values of the ionicity are in support of this argument.
Materials Today: Proceedings, 2019
Selenium-based chalcogenide glasses are best suitable materials for optical data storage due to their amorphous-tocrystalline phase transformation. Average coordination number and number of constraints for Ge 10-xSe 60 Te 30 In x (x = 0, 2, 4, 6) system have been discussed with two topological effects, floppy and rigid transition. Mean bond energy and glass transition temperature have been investigated using chemical bond approach to understand structural features of glasses. Heat of atomization, mean bond energy and glass transition temperature have been studied theoretically.
— Se-Te based chalcogenide glasses have been found suitable for optical memory devices due to their distinct amorphous-to-crystalline transformation. In the present work alloys of Se 65 Ge 15 Te 20-a Sb a (a = 3, 6, 9, 12, 15, 18) glasses have been synthesized using melt quench technique. Author report investigations leading to optical, thermal and topological properties of these glasses by varying the concentrations of Te and Sb. Glass transition and crystallization kinetics of alloys have been investigated using differential thermal analysis at different heating rates (5, 10, 15, and 20 Kmin-1). The results so obtained verify the usefulness of above composition.
Effect of Compositional Dependence on the Physical Properties of Sn-Se-Sb Chalcogenide Glasses
Universal Journal of Physics and Application
Sn 13 Se 87-x Sb x (x = 0, 3, 6, 9, 12) glassy system is synthesized by melt quench technique. This glassy system has been studied for various physical parameters viz. coordination number, lone pair of electrons, number of constraints, bond energy, heat of atomization, glass transition temperature, cohesive energy, band gap and mean bond energy. From the physical analysis it is generalized that the average number of constraints, average heat of atomization, mean bond energy, glass transition temperature and cohesive energy are found to increase whereas numbers of lone pair of electrons calculated are found to decrease with the increase in the antimony content in the composition of the alloy. The increase in glass transition temperature has been explicated on the basis of accumulation of antimony atoms in selenium chain.
Glass-formation region of ternary Sn?Sb?Se-based chalcogenide glasses
Journal of Materials Science, 2005
Tin-antimony-selenium (TAS)-based system belongs to the ternary chalcogenide compounds of IV-V-VI group owing to their heavy elemental masses, their glass formation region was assumed to be small comparing to their counterpart elements in the same group. However, there were rare published reports on their glass structure, while their glass boundary formation region was not yet reported. It was the aim of this paper to map their glass-forming region experimentally using XRD and validate it theoretically using the average coordination number, µ, and the fraction of the bond distributions, f , from chemical order model. Theoretically, it was validated that the glass formation was arrested between µ ≤ 2.4 and the fraction of Sn-Se bonds, f Sn-Se < 44.5%. XRD analyses of 66-as-prepared samples revealed that the glass formation region was located within the predicted area that mapped in structural triangle.
Structural transformation on Se 0.8Te 0.2 chalcogenide glass
Journal of Non-crystalline Solids, 2008
Using X-ray diffraction and differential scanning calorimetry (DSC), the structure and the crystallization mechanism of Se 0.8 Te 0.2 chalcogenide glass has been studied. The structure of the crystalline phase has been refined using the Rietveld technique. The crystal structure is hexagonal with lattice parameter a = 0.443 nm and c = 0.511 nm. The average crystallite size obtained using Scherrer equation is equal 16.2 nm, so it lies in the nano-range. From the radial distribution function, the short range order (SRO) of the amorphous phase has been discussed. The structure unit of the SRO is regular tetrahedron with (r 2 /r 1 ) = 1.61. The Se 0.8 Te 0.2 glassy sample obeys the chemical order network model, CONM. Some amorphous structural parameters have been deduced. The crystallization mechanism of the amorphous phase is one-dimensional growth. The calculated value of the glass transition activation energy (E g ) and the crystallization activation energy (E c ) are 159.8 ± 0.3 and 104.3 ± 0.51 kJ/mol, respectively.
Structure and thermal analysis of Se100−x(SbSn)x chalcogenide glasses
Journal of Non-Crystalline Solids, 2015
Se 100 − x (Sb 0.5 Sn 0.5) x (3 ≤ x ≤ 12 at.%) glassy alloys were prepared using the melt quenching technique. The amorphous nature of the as-prepared samples was confirmed by scanning electron microscope (SEM) and Xray diffraction (XRD) and the effect of the addition of Sb 0.5 Sn 0.5 content on the glass transition and crystallization kinetics of amorphous Se has been studied. The glass transition temperature (T g) was increased with increasing content of Sb 0.5 Sn 0.5. This behaviour was discussed in terms of glass density (ρ), cohesive energy (CE) and the overall mean bond energy bEN. The values of the activation energy of crystallization were increased with increasing Sb 0.5 Sn 0.5 content that was confirmed by increasing the Hruby's parameter (K rg) with the increase of Sb 0.5 Sn 0.5 content. Furthermore, the difference between T c and T g was increased due to the delay in nucleation process. This leads to the enhancement of the thermal stability and consequently the glass forming ability.
Chalcogenide Letters
Compositional trend of the glass transition temperature and the effective activation energies of the glass transition and crystallization processes in Te 20 Se 80-x Sb x glasses (x = 1.5, 3, 4.5, 6, 7.5, 9 at.%) was investigated by differential scanning calorimetry (DSC) technique. The concept of mean coordination number, r , was used to describe the connectivity of the covalent networks of the present samples. The connectivity is enhanced with Antimony as indicated by an increase in T g with x. Two linear regions in the T g (x) relationship can be identified with a kink observed at x ≈ 4.5 corresponding to r ≈ 2.045. A striking similarity between the kinetic behavior of glass transition and crystallization processes was found. In both processes, a change in behavior was observed at the same crossover mean coordination number.