Indian Journal of Physics最新文献

Cesium-based perovskites are emerging optoelectronic materials that offer high thermal and structural stability while also serving as non-toxic alternatives to lead-based perovskites. We have scrutinized the physical properties of Cs₂XAuF₆ (X = Al, Ga) by using first principles analysis. The mBJ is employed to treat the electron–ion interaction. Volume optimization curves and lattice optimized parameters are obtained via Birch’s equation of state. The computed elastic constants for Cs₂XAuF₆ (X = Al, Ga) obey Born’s stability criteria. The analyzed hardness factor for both studied halides signifies materials’ higher endurance to external indentation. The computed Debye and melting temperatures elaborate that these materials are of great importance in high temperature applications. The electronic attributes revealed direct bandgaps of 3.51 eV and 2.92 eV for Cs₂AlAuF₆ and Cs₂GaAuF₆. The optical analysis of the studied halides signifies that these materials are effective for UV-based optoelectronics. The BoltzTraP code is exercised to determine the electronic transport properties for Cs₂XAuF₆ (X = Al, Ga). High ZT values of these two compounds elaborate their significance in the thermoelectric devices.

This study investigates the dynamics of multi-lane totally asymmetric simple exclusion processes (TASEP) with narrow entrances, focusing on the interactions among heterogeneous particle types moving through parallel lanes without changing lanes. The results reveal a significant suppression of high-density phases in the internal lanes of the system, an effect that intensifies with an increasing number of lanes. Through comprehensive Monte Carlo simulations combined with both simple and cluster mean-field analyses, the cluster mean-field approach demonstrates superior accuracy compared to traditional mean-field theory. This improvement arises because the cluster method explicitly incorporates vertical site correlations, a critical factor often neglected by conventional approaches. This study adopts a four-lane model as the primary framework, making significant contributions to non-equilibrium statistical mechanics while establishing a foundation for future research on complex multi-lane transport systems.

Iron oxide is one of the most promising materials for energy storage due to its elevated dielectric constant. However, its significant dielectric loss and structural instability limit its efficiency in practical applications. This study explores the effect of gadolinium (Gd) substitution on the structural and dielectric properties of iron oxide. Gd_xFe_2−xO₃ nanoparticles were synthesized via a sol–gel method followed by supercritical drying. X-ray diffraction confirmed the transformation from a rhombohedral α-phase in pure iron oxide to a stabilized cubic maghemite phase upon Gd incorporation, with no secondary phases detected. Dielectric measurements across varying frequencies and temperatures revealed that Gd doping significantly reduces both the dielectric constant and dielectric loss, making these materials more suitable for high-frequency energy storage applications. Scanning electron microscopy analysis indicated that Gd substitution led to a decrease in grain size and an increase in surface roughness, thereby improving the overall material properties. These findings highlight the potential of Gd-doped maghemite as a versatile material for next-generation electronic and energy storage devices.

The Sun generates energy via two basic nuclear fusion processes: the p–p chain and the CNO cycle. In this study, we calculated the cross sections data for (p,γ) and (p,α) nuclear fusion reactions involving ⁷Be, ¹²C, ¹³C, ¹⁴N, and ¹⁵N in the p–p chain, and the CNO cycle using TALYS 1.95 and EMPIRE 3.2.3 for proton incident energies in the range of 0.5–10 MeV. The calculated cross sections for hydrogen burning were compared with theoretical data TENDL–2021; TEND–2023, Tel et al. (EPJ Web Conf 128, 2016), and experimental data. Furthermore, the obtained cross sections data were used to calculate the astrophysical S-factor over the range of 0.5–10 MeV and thermonuclear reaction rates within the T₉ temperature range of (1–10) × 10⁹ K. The results were verified using datasets from TENDL–2021 and TENDL–2023, Tel et al. (2016), and Angulo et al. (Nucl Phys A 656:3, 1999), and compared with experimental data. The study verifies the reliability and effectiveness of TALYS 1.95 and EMPIRE 3.2.3 in modeling nuclear reactions for specified isotopes at certain energies and temperatures. Additionally, Sunspot data for Solar cycle 25 in Kirkuk, Iraq, was recorded using a refracting telescope, confirming local observations' accuracy with records from NOAA and Helio4Cast.

Polymethyl methacrylate (PMMA) nanoparticles (NPs) integrated with alumina (Al₂O₃) nanocomposite films were prepared using a solution-casting method. XRD, FTIR, SEM, and TEM analyses were used to characterize the obtained composite films. The study investigated the impact of Al₂O₃ nanoparticles (Al₂O₃ NPs) on the optical characteristics of the PMMA polymeric matrix using UV–Vis-NIR optical spectroscopy. The fabricated films demonstrated unique light-blocking capabilities within a range of 190–275 nm. Optical energy gaps changed dramatically when Al₂O₃ nanoparticles were added to polymeric chains of PMMA. The direct optical gap decreased from 4.95 to 4.85 eV, while the indirect optical gap decreased from 4.78 to 4.5 eV. The behavior of the Urbach energy (E_U) increases with increasing Al₂O₃ NP loading. The study demonstrated remarkable optical limiting capabilities using two laser sources with wavelengths of 632.8 nm and 533 nm. The inclusion of Al₂O₃ NPs resulted in an enhanced dielectric constant, indicating increased polarization of particles within polymeric films at reduced frequencies. As Al₂O₃ NPs content and frequency increased, AC conductivity also increased. PMMA/Al₂O₃ composite films demonstrated a photocatalytic degradation efficiency of 96.15% and a reaction rate constant of 0.0284 min⁻¹ in degradation of RhB dye with (1.66 wt.%) alumina content exhibited the highest efficacy under UVA light. ^·OH radicals are the reactive species responsible for the degradation of RhB dye. These promising outcomes suggest the potential multifunctional applications of Al₂O₃/PMMA nanocomposite films, including their use as laser optical limiters and photocatalytic membranes for wastewater treatment, reinforcing their utility in various domains.

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In this comprehensive first-principles study, the structural, phonon, electronic, optical, and elastic properties of Ba₂XSbO₆ (X = Dy, La) double perovskite oxides were systematically investigated using density functional theory (DFT). Both compounds exhibit structural stability in magnetic and non-magnetic phases, as confirmed by the Birch–Murnaghan equation of state. The electronic band structure reveals that Ba₂DySbO₆ is a spin-polarized half-metal, indicating strong potential for spintronic and magnetic semiconductor applications, while Ba₂LaSbO₆ is a wide-bandgap direct semiconductor, making it suitable for optoelectronic use. The density of states highlights Dy-f orbital dominance near the Fermi level in Ba₂DySbO₆, with Ba and Sb contributing to bonding interactions in both materials. Optical analyses show Ba₂LaSbO₆ possesses excellent dielectric properties (ε₁ ≈ 6 eV), high absorption (160 × 10⁴ cm⁻¹ at 9 eV), and notable optical conductivity (6000 Ω⁻¹ cm⁻¹ at 6 eV), making it promising for UV-protective and optoelectronic applications. Mechanically, Ba₂LaSbO₆ demonstrates higher stiffness (Y = 172.91 GPa, G = 68.35 GPa), while Ba₂DySbO₆ shows enhanced ductility (B/G = 2.96), suggesting potential for flexible devices. Additionally, Ba₂LaSbO₆ shows a higher refractive index (~ 3.5) and reflectivity (~ 30% at 5 eV), supporting its suitability for optical coating technologies.

In this article, we have investigated a string cosmological model within the context of f(R, T) gravity theory in a homogeneous yet anisotropic higher-dimensional (HD) Bianchi Type-III space-time. A cosmic string is considered as the source of the energy-momentum tensor and (f(R,T) = R + 2f(T)). The solutions to the associated field equations were derived by assuming the shear scalar (sigma) to be proportional to the expansion scalar (theta), resulting in (xi = chi ^{n}). Then we determine the best fit ranges of the model parameters using the updated H(z) data, which includes 31 H(z) measurements from cosmic chronometers (CC) and 1048 data points from the Pantheon supernova compilation. Additionally, we have computed and examined various physical and kinematic attributes of the cosmological parameters, including the equation of state(EoS), jerk parameter, snap parameter and evaluated the energy conditions of the model along with its stability criteria. Moreover, we have illustrated the behavior of the cosmological parameters graphically for specific fixed values of the observational constants.

The energies and angles of critical minima (CM) in differential cross sections (DCSs) of elastic electron scattering by atoms of the sequence from Na to Ar were calculated. The DCSs are characterized by the presence of both the low-angle and high-angle CM: four each for atoms Na, Mg and S; five each for atoms Al, Si and Ar; six for Cl atom and seven for P atom. The dependences of energies from the nucleus charge Z for some CM of these atoms are shown. In a wide range of collision energies, from 0.1 to 500 eV, the energy dependences of the angular positions θ_min(E) of the minima, which appear on DCSs, were studied. The energies and angles of the total spin polarization points, the appearance of which is due to CM, were determined. Intervals where the absolute value of the Sherman functions is at least 0.20 (20%) are also determined. The phase shifts which are necessary to obtain the scattering amplitudes, Sherman functions and DCSs for above scattering process were calculated in the relativistic complex optical potential approach.

In this research work, the solid-state reaction method was used to synthesize (Gd, Ni) doped cerium oxide Ce_(2-(x+y)) Gd_xNi_yO₂ powder samples. The Characteristics of annealed sample powders and the effect of annealing on these properties were investigated. XRD confirmed the cubic structure. Due to the Gd–Ni content, the crystallite size varied from 38.95 to 25.71 nm, while the lattice parameters improved from 5.431 to 5.501 Ǻ. Surface morphology (SEM) was almost spherical, and particle diameter grew with Gd–Ni concentration. Elemental studies (EDAX) confirmed that O, Ce, Gd, and Ni achieve the desired atomic ratio. According to the optical investigations, the optical band gap of the powders increases from 2.712 to 3.150 eV. The photoluminescence (PL) analysis of pure and Ce_(2-(x+y) Gd_xNi_yO₂ nanopowders at excitation wavelengths of 407 nm displayed indigo, green, orange, and red emission in the 425–800 nm range. From the Vibrating Sample Magnetometer (VSM) studies, the magnetic characteristics revealed for nanopowder samples present paramagnetic properties. The magnetic moment of pure and Gd–Ni doped samples varies from 0.0047 to 0.0635 emu/g, with a coercive field ranging from 16.34 to 2.94 Oe. The outcome observed is analyzed and deliberated upon in this study.

Molecular dynamics simulations were conducted to investigate diffusion in sodium silicate glasses at temperatures of 973, 1173, and 1373 K, with a focus on Na⁺ transport through simplexes. The result shows that the simplexes completely cover the depolymerized region of the silicate network and exhibit broad distributions in radius and number of bridging oxygens (n_BO = 0, 1, 2, 3, and 4). Sodium ions are found to preferentially occupy and migrate through large simplexes (or simplexes with low n_BO), which facilitates very fast sodium diffusivity compared to Si and O. We have established an expression for sodium diffusion constant based on the mean square displacement of sodium per simplex and the average time spent by Na on simplex (t_S). The analysis reveals that the changes in sodium diffusivity with temperature or SiO₂ content are primarily attributed to varying t_S.