Browsing by Author "Ishu Sharma"

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Assessment of gamma and neutron shielding features of Se80-yTe20My (M = Fe, Co, Ni, Cu, y = 0 and 2) alloys for radiation safety applications
(2025) Nisha Kumari; Vishnu Saraswat; Shiv Kumar Pal; Ishu Sharma; Z. Y. Khattari; Neeraj Mehta
[No abstract available]
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
Pre-crystallization and recrystallization kinetics of melt-quenched Se78Te20Sn2and Se76Te20Sn2M2(M = Ge, In, Pb, Sb) glass–ceramic alloys
(Royal Society of Chemistry, 2025) Kaushal Kumar Sarswat; Ishu Sharma; Neeraj Mehta
This study explores the impact of Ge, In, Pb, and Sb additives on the kinetic behaviors of pre-recrystallization and recrystallization in Se78Te20Sn2 alloys. Non-isothermal calorimetric experiments were conducted to determine the glass transition temperature (Tg), recrystallization onset temperature (To), peak temperature (Tc), and associated activation energies (Eg, Ec). Parameters such as Lasocka's coefficients (Ag, Bg, Ac, Bc), recrystallization rate constant (K), Hruby number (Hr), and thermal stability (S) were evaluated to assess the glass-forming tendencies and resistance to devitrification. Additives significantly influenced Tg, Tc, and Ec, with Sb yielding the highest thermal stability and glass-forming ability. Stability criteria based on the Arrhenius rate constant K(T) highlighted the correlation between configurational changes and energy barriers. These findings offer insights into thermal behavior, enabling the design of tailored glass–ceramic alloys for advanced applications. This journal is © The Royal Society of Chemistry, 2025
Thermodynamic behavior and related phase transitions in SeTeSn and SeTeSnM (M = Ge, In, Pb, and Sb) chalcogenide glass ceramics
(Elsevier B.V., 2025) Kaushal Kumar Sarswat; Ishu Sharma; Neeraj Mehta
This study addresses the critical need for a deeper thermodynamic understanding of chalcogenide glass–ceramic systems by investigating Se76Te20Sn2 and Se78Te20Sn2M2 (M = Ge, In, Pb, Sb) alloys. Although previous research has focused on thermal stability and crystallization behavior, limited attention has been given to the systematic analysis of specific heat behavior and its kinetic correlations near the glass transition temperature (Tg). While prior studies have emphasized thermal stability and crystallization, this work focuses on the composition-dependent evolution of specific heat (Cp) across the glass transition temperature (Tg). Differential scanning calorimetry (DSC) was employed under non-isothermal conditions to evaluate the specific heat (Cp) and derive associated thermodynamic parameters: enthalpy (H), entropy (S), and Gibbs free energy (G). Two novel kinetic–thermodynamic correlations were identified: (i) a linear relationship between the rate of conversion change Δ(dα/dT) and logβ, and (ii) a direct correlation between the specific heat jump (ΔCp) and logβ. These results offer new insights into how heating rate influences thermal transitions. The thermodynamic profiles of Cp, H, S, and G exhibit continuous transition characteristics, indicating that Tg functions as a dynamic threshold rather than a sharp boundary. This work contributes to a deeper understanding of glass transition phenomena and provides a framework for tailoring phase-change behavior in functional chalcogenide materials. © 2025
Zinc-induced bandgap modulation and nonlinear optical response in SeTeSn thin films
(Elsevier Ltd, 2025) Vishnu Saraswat; A. Sameer Ruban Kumar; S.S Salah Fouad; H. Atiya; Ishu Sharma; Neeraj Mehta
This work investigates the optical properties of zinc-containing amorphous thin films (TFs) in the multicomponent STS system. Critical optical features relevant to applying chalcogenide glasses (ChGs) in optoelectronics and optics have been thoroughly examined. Experimental spectrum data on transmission and reflection in the wavelength range of 4000 Å to 25,000 Å were used to explore the optical behaviour of the generated TFs. Important metrics, including the absorption and refractive indices, were assessed. Examining the spectrum fluctuation of dispersion characteristics allowed for determining the Urbach energy (Eu) and optical bandgap (Egopt). The optical bandgap exhibited a notable increase across the samples: a rise of 0.23 eV for the STSZ4 sample, 0.22 eV for STSZ6, and 0.16 eV for STSZ2, indicating significant changes in the bandgap with zinc incorporation. Additionally, the Urbach energy showed a substantial increase, particularly in the STSZ4 sample. The study confirms an indirect optical transition, supported by the transition power factor (m). Furthermore, single-oscillator dispersion characteristics and a high dielectric constant (ε′) were determined. The study also investigates how the volume and surface energy loss functions, relaxation time (τ), dissipation factor (tanδ), and real (ε′) and imaginary (ε′′) components of the optical dielectric constant rely on photon energy (ℎν). Notably, the infinite dielectric constant (ε∞) of the parent STS TF (ε∞ = 3.43) increases outstandingly after doping with STSZ2 (ε∞ = 6.78), STSZ4 (ε∞ = 2.03), and STSZ6 (ε∞ = 3.51). For the multicomponent STSZ system, optical and electrical conductivities and Nonlinear optical properties were also investigated. © 2025 Elsevier Ltd and Techna Group S.r.l.