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    Correlations in Cu-based chalcogenides for optical and transport performance in sustainable technologies: First-principles calculation
    (Elsevier Ltd., 2025) Moharam, M.M.; İrfan, Muhammad; Asif, Sana Ullah
    Researchers have taken an interest in semiconductor chalcogenide compounds because of the wide variety of physical properties that these compounds exhibit. The study of the elastic, optical, and thermoelectric properties of Cu-based AlCu3PbX4 (X = S, Se, Te) chalcogenides has been conducted using the PBEsol-mBJ scheme within the framework of Density Functional Theory (DFT). The calculated band structure shows that both direct band gaps are semiconducting (1.0 eV–1.8 eV) as the valence band maximum (VBM) is primarily formed of Cu-d states. The conduction band minima (CBM) is primarily Al/Pb-s, p states. The optical and thermoelectric properties of AlCu3PbX4 (X = S, Se, Te) have been thoroughly examined using first-principles calculations. The dielectric function analysis reveals a static dielectric constant of 5.5–8.6, with significant peaks in the visible and ultraviolet regions. The refractive index varies between 2.0 and 2.8, while the absorption coefficient reaches a maximum of 180 cm−1 in the UV range, indicating strong optical absorption. These materials exhibit high reflectivity (>40 %) at photon energies exceeding 4 eV and a plasmon energy loss peak near 13 eV. Zener anisotropy factor deviating from 1, indicates anisotropic elastic behavior, while Pugh's ratio (B/G), which is less than 1.75 for these materials, further classifies them as brittle in nature. Thermoelectric investigations using Boltztrap show high Seebeck coefficients of 250–400 µV/K, power factors of 2.0 × 1010 to 8.0 × 1010 W/mK2s, and impressive dimensionless figure-of-merit (ZT) values of 0.1–1.1 at temperatures (∼800 K), demonstrating their potential for high-efficiency thermoelectric applications. These findings suggest that AlCu3PbX4 compounds are promising candidates for energy-efficient thermoelectric and optoelectronic devices. © 2025 Elsevier Ltd
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    Examining Computationally the Physical Properties of Novel Lead-Free Eco-Friendly Chloroperovskites for Energy Applications
    (Springer, 2024) İrfan, Muhammad; Ahmed, Emad M.; Issa, Shams A. M.; Zakaly, Hesham M. H.
    This paper explores the various characteristics of the Li2Zr6MnCl15 chloroperovskites, including their structural, electronic, magnetic, optical, phononic, and thermoelectric properties. The computed phonon dispersions and formation energies provide strong evidence for the stability of this compound. Based on the analysis of magneto-electronic properties, it is observed that Li2Zr6MnCl15 demonstrates a semiconductor (2.2 eV Up/0.55 Dn) behaviour with a magnetic moment of 4.00 µB. Comprehensive analysis of optical properties involved intricate calculations of various parameters related to the behaviour of light, such as dielectric constants, refractive indices, reflectivity, extinction coefficients, electron energy loss, absorption coefficients, and optical conductivity functions up to 14.0 eV. The research was carried out in the temperature range of 50 to 800 K to determine the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor (PF), Hall coefficient, and figure of merit for the investigated material, which showed great promise for use in thermoelectric devices, with PFs of about 7.5 × 104 W/K2ms, respectively. Using the application known as phy-x: PDS, All of the gamma radiation shielding parameters of Li2Zr6MnCl15 were determined, including mass attenuation coefficient (GMAC), linear attenuation coefficient (GLAC), half value (GHVL), mean free path (GMFP), the effective, effective atomic number (Zeff), and effective electron density (Neff). The research indicates that the GMAC and GLAC values for Li2Zr6MnCl15 fall as the photon energy rises, with a noteworthy increase near K-edge absorption owing to the photoelectric effect dominance at low energy. Both Zeff and Neff declined as the photon energy increased, with Zeff reducing from 25.56 to 25.27 and Neff decreasing from 3.22 × 1023 to 3.18 × 1023 electrons/g. Due to their robust absorption patterns and high PF, these compounds show great promise as thermoelectric and optoelectronic materials. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
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    First principles computation of exchange mechanism, radiation shielding, and physical properties of FeCu2SnX4(X=S, Se, Te): Transitions metal based chalcogenides for spintronic and energy storage system applications
    (Elsevier Ltd., 2025) Sohail, Shahzad; İrfan, Muhammad; Ain, Quratul; İbrahim, Fatma A.; Hamdy, Mohamed S.; Zakaly, Hesham M.H.
    This study explores the multifunctional properties of Cu-based FeCu2SnX4(X = S, Se, Te) through density functional theory (DFT) calculations, focusing on their ferromagnetic stability, optical behavior, and thermoelectric performance. Phonon dispersions and negative formation energy values validated the stability of the ferromagnetic phase of all the investigated spinels. Band structure analysis confirmed semiconducting characteristics for both spin channels, while exchange splitting energies obtained from the density of states (DOS) were used to calculate exchange constants (N0α and N0β). The strong p-d hybridization, reflected in higher N0β = −0.14, −0.18, and −0.16 and N0α = 0.11, 0.29, and 0.35, indicated that the exchange field dominates the crystal field, driving ferromagnetism. Furthermore, p-d hybridization adjusted magnetic moments at Cu and Fe sites, showcasing tunable magnetic properties. Optical analysis in the 0–6 eV photon energy range revealed low light dispersion and refractive indices of 1–2 eV within the visible spectrum, suggesting potential for optoelectronic applications. Thermoelectric studies at 500 K demonstrated positive Seebeck coefficients for FeCu₂SnS₄ and FeCu₂SnSe₄, while FeCu₂SnTe₄ showed negative coefficients at room temperature. Power factors increased with temperature from X = S to Te, highlighting their potential for thermoelectric power generation. Furthermore, the radiation shielding assessment emphasized that FeCu2SnTe4 provides an HVL of a minimum of 0.18 cm at 0.015 MeV, which clearly explains gamma-ray absorption more than other samples. This information places FeCu₂SnX₄ spinel structures as potential candidates for applications that require combined magnetic, optical, radiation shielding, and energy functionalities. These findings position FeCu₂SnX₄ spinels as promising materials for integrated magnetic, optical, radiation shielding, and energy applications. © 2025 Elsevier Ltd
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    First principles investigations of linear and nonlinear optical, radiation shielding and thermoelectric properties of the non-centrosymmetric Ba-based chalcogenides Ba2In2X5 (X=S, Te)
    (Elsevier Ltd., 2025) İrfan, Muhammad; İbrahim, Fatma A.; Hamdy, Mohamed S.; Issa, Shams A.M.; Zakaly, Hesham M.H.
    We explore the structural, elastic, optoelectronic, Radiation Shielding, and thermoelectric properties of Ba2In2X5 (X = S, Te) using first-principles computations and semi-classical Boltzmann Transport equations. These materials are classified as semiconductors exhibiting band gaps of 2.0 eV and 3.0 eV for both investigated NLO compounds that have more significant direct band gaps of superior optical birefringence and second-order NLO coefficients. The bonding properties have been investigated by analyzing the electron charge density (ECD) contour of the (1 0 1) crystallographic plane. It is clear from the reflectivity spectra that both compounds have a high degree of reflectivity, which could make them useful as UV and visible light shields. From 0 to 14.0 eV, the approximated reflectivity values, R (ω), are displayed against the incident photon energy. Therefore, the reflectivity is around 30 % before E ≈ 12.0 eV and 40 % reflection at ∼13.0 eV. Phase matching is possible for both compounds detected, as shown by the birefringence computations. Furthermore, the radiation shielding properties of Ba2In2S5 and Ba2In2Te5 have been evaluated using Phy-X software, demonstrating their potential effectiveness in medical and nuclear energy applications. The thermoelectric properties display N-type nature at low temperatures when the Seebeck coefficient changes from N to P-type at higher temperature ranges. These compounds have remarkable optical and thermal properties, rendering them highly attractive materials for thermoelectric and optoelectronic devices. © 2024 Elsevier Ltd