Browsing by Author "A. Dahshan"

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A comprehensive iso-conversional analysis of recrystallization in Se78-xTe20Sn2Mx (x = 0, 2; M = In, Ge, Sb, and Pb) alloys
(Elsevier B.V., 2025) Kaushal Kumar Sarswat; A. Dahshan; Neeraj Mehta
The model-fitting non-isothermal methodologies provide valuable insights into the recrystallization, delineating the comprehensive activation energy involved. Investigating the kinetics parameter of recrystallization using their dependence on the conversion reveals meticulous aspects of the recrystallization that cannot be achieved using the non-isothermal model fitting methods. With this perspective in mind, our investigation delves into the iso-conversional analysis of the recrystallization in Se78-xTe20Sn2Mx (x = 0, 2; M = In, Ge, Sb, and Pb). In the present article, we have examined the dependence of iso-conversional activation energy Ec, recrystallization rate constant energy Kc, and order parameter n as a function of the temperature and the degree of conversion αc. Furthermore, we have observed the validity of the Meyer-Neldel compensation rule in the iso-conversional recrystallization. The effect of In, Ge, Sb, and Pb on the iso-conversional kinetic parameters (Ec, Kc, and n) has been analyzed by measuring their percentage change before and after the recrystallization. © 2024 Elsevier B.V.
A comprehensive study of radiation shielding parameters of chalcogens-rich quaternary alloys for nuclear waste management
(Elsevier B.V., 2024) Kaushal Sarswat; Shiv Kumar Pal; Z.Y. Khattari; A. Dahshan; Neeraj Mehta
The current study examines the impact of metal additives on the shielding characteristics of Se76Te20Sn2M2 (where M = Ge, In, Sb, and Pb). These glasses are useful as shielding materials against high-energy radiation, such as X-rays and ϒ-rays, because these glasses have better values of shielding parameters compared to other potential candidates in the race for nuclear safety applications. To this end, we have calculated various radiation-related protection parameters using an online application called Phy-X/PSD. Using this program, we have estimated a complete list of radiation shielding parameters. The impact of the fourth element M (M = Ge, In, Sb, and Pb) on these parameters is also discussed. The maximum mass attenuation coefficient (MAC) was recorded at a photon energy of 15 keV for the incorporation of lead. Half-value layer (HVL) values peaked at 6 MeV and it attained its maximum value for germanium. The highest and lowest values of the linear attenuation coefficients (LAC) were obtained for Se76Te20Sn2Pb2 and Se76Te20Sn2Ge2 alloys respectively. Notably, the Se76Te20Sn2Pb2 alloy exhibited the highest values of effective atomic number (Zeff), electron density (Neff), atomic cross-section (ACS), and electronic cross-section (ECS), indicating superior shielding performance. Conversely, energy absorption buildup factors (EABF) and exposure buildup factors (EBF) were highest for Se76Te20Sn2Ge2 alloy. Neutron attenuation was most effective in the Se76Te20Sn2In2 and Se76Te20Sn2Pb2 compositions. Overall, the incorporation of lead in the parent glass demonstrated superior shielding capability compared to the other compositions studied. © 2024 Elsevier B.V.
A new approach for nano-structuring of glassy selenium (g-Se) using silver nanoparticles (AgNPs) as precursor
(Elsevier Ltd, 2021) Amit Kumar; N. Mehta; A. Dahshan
Various routes have been proposed for the synthesis of chalcogen based nanostructured materials but the search of conventional and cost-effective method for the nanostructuring of chalcogenides is an ongoing research activity. This unique work reports the synthesis and the characterization of a novel kind of glassy nanocomposite material belonging to the nano-structuring of g-Se with the help of silver nanoparticles. The local structure is analyzed with the help of X-ray diffraction, Scanning electron microscopy, Raman spectroscopy, and Differential Scanning Calorimetry. It was found that the addition of AgNPs in glassy Se creates fine nano-wires of trigonal Selenium (t-Se) in the glass matrix of g-Se. The electrical, mechanical, and thermal characterizations of the present glassy nanocomposite material have been done in terms of current-voltage characteristics, d.c. conductivity, micro-hardness, and kinetic parameters of glass/crystal phase transformation. A comparative analysis of present glassy composites with a conventional Ag containing glassy alloy (g-Se98Ag2) has also been done to understand the role of incorporation of silver nanoparticles over the normal silver powder. The detailed analysis shows that different physical properties [e.g., thermal stability, modulus of elasticity, micro-hardness, the threshold voltage (i.e., turn-on voltage for resistive switching), and d.c. conductivity] are enhanced more effectively when the nano-structuring of g-Se by using AgNPs is executed as compared to the routine way of alloying. © 2020 Elsevier Ltd
Analysis of shielding effectiveness of quaternary SeTeSnSb glasses
(Elsevier Ltd, 2025) Shiv Kumar Pal; Z. Y. Khattari; A. Dahshan; Neeraj Mehta
In this endeavour, we have reported the effect of antimony as a chemical modifier in parent STS glassy systems in studying its radiation shielding capabilities. Using a renowned melt-quench method, we have synthesized a glassy Se78-xTe20Sn2Sbx (0 ≤ x ≤ 6) system. Compared to other prospective candidates in the race for nuclear safety applications, these glasses have greater shielding characteristics, making them effective as shielding materials against high-energy radiation, such as X-rays and ϒ-rays. To achieve this, we used an online program called Phy-X/PSD to compute radiation-related protection parameters. We have estimated an exhaustive list of radiation shielding parameters using this application. The impact of the antimony on these parameters is also discussed. © 2025 Elsevier Ltd
Comprehensive studies of dielectric behavior, resistive switching, and a.c. conduction in zinc-containing quaternary glasses of Se-Te-Sn
(Elsevier B.V., 2023) Vishnu Saraswat; Shiv Kumar Pal; A. Dahshan; Neeraj Mehta
The dielectric behavior, thermally activated a.c. conduction and resistive switching form the basis for revealing new information about the conduction mechanics of glassy chalcogenide materials. Zinc has been chosen as a modifier to control different electrical properties in a parent ternary glass Se78Te20Sn2 of Se-Te-Sn system in the present work keeping in mind the exceptional physical properties of zinc chalcogenides. The detailed analysis indicates that dielectric constant (ε′), dielectric loss (ε″), and a.c. conductivity (σac) is changed appreciably with varying concentrations of zinc atoms in the parent glass. The a.c. conduction follows the correlated barrier hopping (CBH) with bi-polaron hopping as the leading conduction mechanism. We have also determined the density of localized states by using the CBH model. Further, the resistive switching is modified significantly after zinc incorporation. The results have been explained using the chemically ordered network (CON) model and heavy cross-linking of glass-matrix due to isomers of SeyZny nanoclusters. © 2023
Correlation between the density of defect states (DDS) and cross-linking of corner/edge sharing GeSe4 tetrahedral structural units
(Elsevier Ltd, 2023) Shiv Kumar Pal; A. Dahshan; Neeraj Mehta
We have estimated the DDS in the STSG [Se78-xTe20Sn2Gex (x = 0, 2, 4, 6)] system by using the Correlated Barrier Hopping (CBH) model by performing A.C. conduction measurements in the frequency range (1 kHz–10 kHz) and temperature underneath the glass transition temperature (303–333) K. The detailed analysis reveals that bi-polaron hopping is a leading conduction mechanism over single-polaron hopping. Further, there is a noticeable reduction in DDS with increasing concentration of Ge beyond the composition x = 2. A close inspection indicates that cross-linking of Se with Ge has an important role in controlling the DDS in terms of the corner/edge sharing configurations in the structural unit of GeSe4 tetrahedral. © 2023
Corrigendum to “Insights into the physical aging in chalcogenide glasses: A case study of a first-generation As2Se3 binary glass” [Coord. Chem. Rev. 442 (2021) 213992](S0010854521002666)(10.1016/j.ccr.2021.213992)
(Elsevier B.V., 2021) Shiv Kumar Pal; Neeraj Mehta; V.I. Mikla; A.A. Horvat; V.V. Minkovich; A. Dahshan
The authors regret the error in density reporting in the table 4 and identification of the first sharp diffraction peak (FSDP) in the XRD pattern. The data reported in the table 3 belongs to the second sharp diffraction peak (SSDP) instead of FSDP. Also, the density values reported in Table 4 were obtained by the experiment on the pellets of the aged/fresh samples of g-As2Se3 instead of the results of bulk samples. The density values for bulk samples are as follows: [Table presented]Also, the updated highlights are included below Highlights • The density data was imported for the pressed pellets that were obtained by pressing the powdered samples in a hydraulic press.• The density values of as-prepared bulk samples are given in the erratum.The authors would like to apologize for any inconvenience caused. © 2021 Elsevier B.V.
Crystallization temperature predictions in phase-change materials using a novel approach
(Elsevier B.V., 2025) Kaushal Kumar Sarswat; Ishu Sharma; A. Dahshan; Neeraj Mehta
A crucial factor affecting chalcogenide materials’ thermal stability and phase transformation behaviour is their crystallization temperature (Tc), which is motivated by iso-conversional analysis. In this study, we present a novel correlation for predicting Tc. The theoretical estimate of Tc provided by the recently developed correlation perfectly matches the values derived from Differential Scanning Calorimetry (DSC) measurements. This agreement demonstrates the precision and dependability of our method for figuring out the kinetics of the crystallization of chalcogenide materials. Our correlation provides a reliable approach for accurate Tc prediction by integrating theoretical and experimental analyses, advancing phase-change materials and their uses. The suggested model enhances our understanding of crystallization dynamics and is a valuable tool for material optimization and design. The crystallization activation energy calculated using our correlation maintains a constant difference from the activation energy obtained through the Various Heating Rate (VHR) method. This study underscores the significance of the proposed method as a powerful tool in crystallization studies, particularly for materials where accurate determination of crystallization temperature is crucial. The observed constancy in the activation energy difference further validates the robustness of this approach. © 2025
Estimation of density of charged defect states in some glasses of SeTeSnPb system using low-temperature d.c. conductivity measurements
(Springer, 2021) Shobhit Saraswat; V.K. Tomar; V.K. Deolia; A. Sharma; A. Dahshan; N. Mehta
The charged defect states in chalcogenide glasses (ChGs) are responsible for the hopping conduction. The estimation of the density of defect states (i.e., DDS) is a crucial task when we choose a specific ChG as electronic material for its utilization in industry-level applications. ChGs are also famous as electronic materials since they possess exceptional electrical properties (e.g., thermally governed ac/dc conduction, resistive switching, dielectric dispersion). The present study reports the results of the low-temperature dc conductivity measurements in some multicomponent glasses of SeTeSnPb. For this, the dc conductivity has been measured in the low-temperature range. The detailed analysis of obtained data indicates that the dc conductivity obeys Mott’s T−1/4 law in this region. The DDS has been determined and its composition dependence is also discussed. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Exploring dielectric and AC conduction characteristics in elemental selenium glass modified with silver halides
(Royal Society of Chemistry, 2024) Anil Kumar; Vishnu Saraswat; A. Dahshan; H.I. Elsaeedy; Neeraj Mehta
In this research work, we have examined the influence of silver halide doping on the dielectric dispersion and AC conduction of elemental selenium. The in-depth investigation shows that when the dopant silver halides are incorporated, there are noticeable changes in the parent selenium's dielectric constant (ϵ′), dielectric loss (ϵ′′), and AC conductivity (σac). When we frame the discussion of the obtained results with the relevant transport models, we found that in pure selenium and Se95(AgI)5, conduction is primarily due to polaron hopping and follows the correlated barrier hopping (CBH) model. In contrast, Se95(AgBr)5 predominantly exhibits non-overlapping small polaron tunneling (NSPT). Interestingly, Se95(AgCl)5 demonstrates both NSPT and CBH conduction mechanisms, depending on the temperature range: NSPT is dominant between 303 K and 313 K, while CBH prevails from 318 K to 338 K. Additionally, our findings revealed the presence of both the Meyer-Neldel rule (MNR) and its reverse in the prepared silver halide chalcogenide alloys. The best optimization of dielectric constant and loss is observed for silver iodide as compared to silver chloride and silver bromide. Comparison with other silver-containing chalcogenide glasses indicates the better dielectric performance of the present silver halides containing selenium. © 2024 The Royal Society of Chemistry.
Exploring dielectric and conductive behavior in indium-doped Se78−xTe20Sn2Inx (0 ≤ x ≤ 6) chalcogenide glasses
(Springer Science and Business Media Deutschland GmbH, 2025) Kaushal Kumar Sarswat; Vishnu Saraswat; A. Dahshan; Neeraj Mehta
An understanding of the conduction mechanism can be supported by the structural information expected to be revealed by studying the dielectric behavior and alternating current (AC) conduction of amorphous materials such as chalcogenide glasses. This script presents our recently synthesized multi-component glasses of the quaternary Se78-xTe20Sn2Inx (0 ≤ x ≤ 6) system, representing our innovative work. We have specifically looked into the dielectric characteristics of these electronic materials. We have examined how the dielectric constant (ε′), dielectric loss (ε″), and AC conductivity depend on temperature and frequency in the audible frequency range (0.1–500 kHz). A thorough investigation revealed that the Guintini model is followed by dielectric loss (ε″). AC conduction follows correlated barrier hopping (CBH), with bi-polaron hopping being the leading conduction mechanism. We have also determined the density of localized states by using the CBH model. The CBH model states that electron hopping occurs over the coulombic barrier height W and the distance R between adjacent sites. The Coulomb wells overlap and lower the effective barrier height from WM to a value of W. We found a new correlation for explaining the barrier hopping. The regression coefficient (R2) for this correlation is 100%. Subsequent investigation reveals that variations in electronegativity explain the sequence of rising charged defect densities and reduce with atomization heat. © The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025.
High-energy radiation shielding characteristics of SeTeSnAg chalcogenide glasses (STSA ChGs)
(Elsevier B.V., 2024) Vishnu Saraswat; A. Dahshan; H.I. Elsaeedy; Z. Khattari; Neeraj Mehta
The focus of the current research is to see the effectiveness of some quaternary ChGs as shielding materials for very energetic radiation such as X-rays and gamma rays. The ChGs addressed in this investigation belong to a quaternary glass system of SeTeSnAg. The online Phy-X/PSD program has been used to determine several parameters (e.g., linear/mass attenuation coefficients) related to radiation shielding characteristics. Further, we have determined various shielding parameters (e.g., Half-Value Layer, mean free path, transmission factor, efficacy of radiation protection, removal cross-section) as well as the mechanical properties (e.g., bulk modulus, shear modulus, longitudinal modulus, and Poisson's ratio). It is also discussed how replacing Se atoms with silver affects the shielding properties of the parent SeTeSn glass. © 2024
High-energy radiation shielding characteristics of SeTeSnM (M = Ag, Bi, Cd, Zn) chalcogenide glasses (STSM ChGs)
(Elsevier Ltd, 2024) Vishnu Saraswat; A. Dahshan; H.I. Elsaeedy; Z. Khattari; Neeraj Mehta
The focus of the current research is to see the effectiveness of some quaternary ChGs as shielding materials for very energetic radiation such as X-rays and gamma rays. The ChGs addressed in this investigation belong to a quaternary glass system of SeTeSnM. The online Phy-X/PSD program has made it possible to deduce several safety factors. We were able to obtain the linear/mass attenuation coefficients thanks to this software. The most intriguing results are that they have values that are better for shielding than some commercial and conventional glasses. Further, we have determined various shielding parameters (e.g., Half-Value Layer, mean free path, transmission factor, efficacy of radiation protection, removal cross-section) as well as the mechanical properties (e.g., bulk modulus, shear modulus, longitudinal modulus, Poisson's ratio, and micro-hardness). It is also discussed how replacing Se atoms with silver, bismuth, cadmium, and zinc affects the shielding properties of the parent SeTeSn glass. © 2024 Elsevier Ltd and Techna Group S.r.l.
High-energy radiation shielding characteristics of SeTeSnZn chalcogenide glasses (STSZ ChGs)
(Elsevier Ltd, 2024) Vishnu Saraswat; A. Dahshan; Z. Khattari; Neeraj Mehta
The focus of the current research is to see the effectiveness of some quaternary ChGs as shielding materials for incoming photon energy in the range of 0.015–15.0 MeV. The ChGs addressed in this investigation belong to a quaternary glass system of Se78-xTe20Sn2Znx (x = 0, 2, 4, 6). The online Phy-X/PSD program has been used to deduce several safety factors. The MAC values of the studied glass have the following sequential order: MACZn-0 > MACZn-2 > MACZn-4 > MACZn-6. The most intriguing results are that they have values that are better for shielding than some commercial and conventional glasses (e.g., at E = 1.0 MeV, LACRS-520 < LACRS-253-G18 < LACZn-0 < LACZn-2 < LACZn-4 < LACZn-6 < LACZn-4 < LACZn-6). Further, we have determined various shielding parameters (e.g., 0.02 < Half-Value Layer < 4.083 cm−1, 0.03 < mean free path <6.90) as well as the mechanical properties (e.g., 40.71 < bulk modulus < 50.55 GPa, 12.16 < shear modulus <15.91 GPa, 49.83 < longitudinal modulus <62.47 GPa, 0.358 < Poisson's ratio < 0.368, and 0.032 < micro-hardness <0.0349 GPa). It is also discussed how replacing Se atoms with zinc affects the shielding properties of the SeTeSn glass. © 2024 Elsevier Ltd
Impact of Ag, Bi, Cd, and Zn incorporation on the kinetic parameters of glass transition/crystallization in chalcogens Se- and Te-rich ternary glass
(Springer Science and Business Media B.V., 2024) Vishnu Saraswat; A. Dahshan; Neeraj Mehta
The present study examines the impact of a few additives, i.e., silver (Ag), bismuth (Bi), cadmium (Cd), and zinc (Zn) on the kinetics of glass transition and crystallization in glassy Se78Te20Sn2 alloy. This is accomplished by performing the calorimetric experiment in non-isothermal mode. To perceive the metal-induced consequences of Ag, Bi, Cd, and Zn as foreign atoms on the kinematics of glass transition, the glass transition temperature (Tg), Lasocka’s glass transition parameters (i.e., A1 and B1), and the glass transition activation energy (Eg) have been calculated. Similarly, we have determined the crystallization temperatures (on-set value To, and peak value Tc) and melting temperature (Peak value Tm), Lasocka’s crystallization parameters (i.e., A2 and B2), crystallization rate constant K, and the corresponding activation energy (Ec). Knowing the values of kinetic temperatures of glass transition/ crystallization, the thermal stability, and the glass-forming tendency of ternary Se78Te20Sn2 and quaternary Se76Te20Sn2M2 (M = Ag, Bi, Cd, and Zn) alloys have been also determined. © Akadémiai Kiadó, Budapest, Hungary 2024.
Impact of micro-indentation load/time and Zinc concentration on the thermo- mechanical characteristics of amorphous Se78Te20Sn2 alloy
(Institute of Physics, 2024) Vishnu Saraswat; A. Dahshan; H.I. Elsaeedy; Neeraj Mehta
We have performed hardness measurement experiments under different loads and loading times by performing micro-indentation marks in the present work. Chalcogenide glasses (ChGs) comprising Se78Te20Sn2 and Se78-xTe20Sn2Znx (where x = 0, 2, 4, & 6) alloys are the subject of micro-indentation tests in this work. We have utilized both micro-indentation and optical microscopic methods to determine Vickers hardness. Thermal glass transition phenomena have been identified through DSC techniques. The modulus of elasticity (E), an essential mechanical property, has been evaluated using established empirical equations. Further, we have studied other mechanical parameters [e.g., minimal micro-void formation energy (E h ), glass’s fragility index (m), micro-void volume (V h ), etc] and the covalent character of the glassy system. Additionally, various physical parameters, including density, molar volume, and compactness, have also been determined. The results emphasize that the different thermo-mechanical parameters investigated in this study achieve their most extreme values at the highest concentration of Zn. However, the energy of micro-void formation within the glassy network of quaternary glasses remains relatively unchanged after the introduction of Zn into the parent STS alloy; © 2024 IOP Publishing Ltd.
Insights into the physical aging in chalcogenide glasses: A case study of a first-generation As2Se3 binary glass
(Elsevier B.V., 2021) Shiv Kumar Pal; Neeraj Mehta; V.I. Mikla; A.A. Horvat; V.V. Minkovich; A. Dahshan
The time-dependent variation in the physical properties is one of the most interesting and mysterious behaviors of melt-quenched disordered solids (like polymer glasses, metallic glasses, and especially in chalcogenide glasses). This phenomenon is recognized as physical aging which reveals that the as-quenched glass stays in a meta-stable state (i.e., a thermodynamically non-equilibrium state) and so a thermally activated structural relaxation is the general characteristics of each glass as a consequence of natural or artificial physical aging (PhA). This review starts with the general introduction of PhA and its features. Different perceptive and peculiarities of PhA have been discussed keeping in mind the case of long-term PhA and anti-aging effects of arsenic in the chalcogenide glasses (ChGs) of the Se-As system. Further, we have reported the case study of As2Se3 stoichiometric glass and the results of some new observations during the natural aging of the Arsenic Tri-Selenide glass (g-As2Se3). The thorough inspection of PhA effects in this industrial glass is done after storing at ambient temperature in a glovebox for ten years. Thermal analysis is done by using differential scanning calorimetry. The XRD and TEM/SEM techniques have been employed for structural analysis. The information of various kinds of bonding is acquired by using Raman spectroscopy. Also, we have determined the thermal stability parameter, Vickers hardness, compactness, fragility, and density of the fresh and old samples of As2Se3 glass to see the consequences of PhA. Finally, the new advances and present status related to the studies of PhA have been discussed. © 2021 Elsevier B.V.
Invariance of Meyer-Neldel compensation rule in thermally activated d.c. and a.c. conduction for as-prepared and aged glassy Selenium and As2Se3 glass
(Elsevier Masson s.r.l., 2021) Shiv Kumar Pal; Neeraj Mehta; V.I. Mikla; A.A. Horvat; A. Dahshan
This paper reports the invariance of the Meyer-Neldel Rule for thermally activated d. c. conduction under the aging effects in glassy Se (g-Se) and As2Se3 glass. For this purpose, we have analyzed the electrical data of the samples (i.e. glassy Se and As2Se3 glass) in bulk form. The fresh samples of both materials were prepared by the well-known melt-quench technique. Particularly, we have done current-voltage (I–V) measurements at different temperatures. Using the I–V characteristics, we calculated d. c. conductivity and the activation energy involved in d. c. conduction for both fresh as well as aged samples. Finally, we observed that the Meyer-Neldel rule holds and Meyer-Neldel characteristic energy are almost the same in both fresh and aged samples of g-Se as well as As2Se3 glass. This indicates that there is no time-dependent variation in the Meyer-Neldel parameter in the present chalcogenide glasses. © 2021 Elsevier Masson SAS
Kinetic modeling and iso-conversional analysis of glass-ceramics of selenium doped with carbon nanomaterials
(Institute of Physics, 2025) Sachin Kumar Yadav; Shiv Kumar Pal; A. Dahshan; Neeraj Mehta
This study addresses a gap in understanding the impact of carbon nanomaterial doping on the crystallization kinetics of selenium glass, particularly when utilizing model-free iso-conversional methods. Previous research has explored the properties of elemental selenium; however, the role of dopants like multiwall carbon nanotubes (MWCNTs) and graphene in altering glass-to-crystal phase transitions at non-isothermal conditions has not been thoroughly analyzed. In the context of selenium glass crystallization, multiwall carbon nanotubes (MWCNTs), and graphene may alter the crystal growth kinetics significantly during glass/crystal phase transformation. Keeping in mind these facts, the present endeavor focuses on analyzing the doping effect of MWCNT and Graphene on the non-isothermal kinetic reaction mechanism of Selenium measured with differential scanning calorimetry (DSC) at different heating rates. The model-free relations such as Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Tang, and Straink methods were applied using iso-conversional approach for determining the activation energy of amorphous to crystalline transformation as well as the Avrami index. Iso-conversional study yields adequate activation energy as a function of the conversion coefficient. We have observed the decreasing behavior of Ec(α) along with the extent of crystallization of four iso-conversional methods. The kinetic triplet parameters (i.e., activation energy Eα, rate constant Kα, and order parameter nα) have been calculated using the VHR method derived from the Johnson-Mehl-Avrami (JMA) rate equation. The value of ‘n’ is reduced with the rise in the value of the extent of conversion α which indicates the reduction in the growth rate of crystallization because of its saturation. This study provides novel insights into the thermal stability and kinetic mechanisms within doped selenium glass-ceramics, expanding the potential applications of chalcogenide glasses in phase-change memory and other fields. © 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.
Optical constants of Sn-doped amorphous Ge-As-Te thin films and their physical characterization
(Elsevier B.V., 2020) Imed Boukhris; Imen Kebaili; Sami Znaidia; R. Neffati; H.H. Hegazy; K.A. Aly; Neeraj Mehta; A. Dahshan
The paper presents theoretical estimations of the effects Sn inclusion on the physical parameters including cohesive energy (CEn), lone-pair electrons (LP), coordination number (CN), constraints number (CON) and heats of atomization (HA) for the Ge12As23Te65-xSnx (where 0 ≤ x ≤ 8 at. %) glasses. In addition, Minkov method helped in evaluating the optical constants of the thin films. It is found that CN, CON, HA and CEn increase whereas LP decreases by increasing the Sn content. It is evident that by increasing the Sn content, the rigidity of the glasses (Ge12As23Te65-xSnx) can be increased. The study helped in estimating the chemical bonds occurred within the Ge12As23Te65-xSnx glasses. Furthermore, by the examination of glasses, it was found that the bonds that exist in glasses are Ge-Sn, Ge-As, Te-As and Te-Te with the respective energies of 42.41, 35.61, 32.74 and 33 kcal/mol. According to the two-term Cauchy dispersion equation, the values obtained from evaluating the refractive index (n) of the thin films were values of oscillator (Eo) and dispersion (Ed) energies. Additionally, the absorption coefficient (α) values were obtained by applying all the suggested conditions of Connell and Lewis. The paper also showed that an increase of the Sn content from 0 to 8 at. %, stimulates to reduce the energy gap (Eg) from 1.5 to 1.25 eV. © 2020 Elsevier B.V.