Indian Journal of Physics最新文献

ZnS quantum dots exhibit remarkable versatility with novel properties and diverse applications. Highly crystalline ZnS quantum dots with cubic structure were prepared using a simple wet-chemical route by varying the sulphur concentration. This work offers an in-depth study of the influence of sulphur concentration on the optical, surface and structural characteristics of ZnS quantum dots. Structural analysis using XRD affirmed the cubic structure of ZnS. FESEM disclosed non-uniform nanosphere-like morphology, while TEM was utilized for particle size determination. Optical characteristics were assessed utilizing UV–Vis spectroscopy and photoluminescence spectroscopy. The ZnS quantum dots synthesized with sulphur concentration double that of the zinc concentration in the precursor solution exhibited the appropriate stoichiometry with minimum point defects. Owing to their high crystallinity, small crystallite size, excellent stability, and suitable optical properties, ZnS quantum dots are favourable candidates for optoelectronic applications.

In this article, we present a detailed investigation of the fractional coupled Higgs system, which is a prominent mathematical model in the field of relativistic quantum theory. By establishing the complex structure of this dynamical model, the study offers a robust framework for comprehending the propagation of long nonlinear waves. An advanced analytical technique, namely, the modified Sardar sub-equation method, is utilized to secure a diverse range of exact solutions to the proposed model. In addition, the dynamical features of the system are analyzed through different tools, including bifurcation, chaos, and sensitivity analysis, presenting valuable insights into the intricate behavior of the proposed model. The derived soliton solutions depict rich profiles, such as dark, dark-bright, W-shaped, singular, periodic, exponential, and mixed trigonometric forms. The physical relevance of these solutions is provided in the form of three-dimensional, two-dimensional, contour, and density graphs. The findings explore that the selected method is highly effective in exploring exact soliton solutions from complex nonlinear systems. This work demonstrates a strong foundation for future investigation in nonlinear sciences and expands its potential applications across various areas of applied mathematics and quantum physics.

Plutonium accumulation from the operation of nuclear power plants presents a critical challenge for nuclear energy management, particularly due to the high decay heat and long-lived isotopes. The addition of plutonium as a thermal and fast reactor fuel material emerges as a potential strategy to reduce plutonium accumulation. The present study aims to investigate the fission reactor physics neutronic parameters such as infinite multiplication factors, reactivity coefficient, and kinetic parameters of the VVER-1000 fuel assembly with the addition of plutonium as a Mixed Plutonium–Uranium nitride fuel material, (Pu,U)N and (Pu,U)N + GdN. Neutronic calculations were carried out using MCNP6 with ENDF/B-VII.1 nuclear data library. The calculation results show that mixed Pu–U nitride fuel exhibits comparable safety characteristics to standard uranium oxide fuel material. Mixed Pu–U nitride fuel shows a better temperature coefficient of reactivity at the beginning of cycle compared to standard uranium oxide fuel_. With proper plutonium fraction adjustment for reactivity, mixed Pu–U nitride fuel can extend the fuel cycle length with its higher excess reactivity but low reactivity swing in fuel assembly level, compared to standard oxide fuel. Further study was needed to optimize the advantages of this fuel assembly in the reactor core. On the other hand, plutonium reduction for up to 19% for Pu-239 after 40 MWD/kg fuel burnup shows that plutonium utilization in the form of mixed Pu–U nitride fuel can be used to reduce the accumulation of plutonium.

It can be interesting to explore new Cr₂-based shape memory alloys with novel properties. In this paper, the site preference, electronic structure, elastic parameters, and magnetic, thermal, and optical properties of new Cr₂Gd-based Heusler alloys Cr₂GdZ (Z = Al, Ga, and In) were investigated theoretically. Using the full-potential linearized augmented plane wave (FP-LAPW) method. The calculated results reveal that the compound is more stable in the AlCu₂Mn prototype in the ferromagnetic phase. The calculated elastic constants show that the compounds satisfy the criteria of stability. We have also computed the mechanical properties, finding that these full-Heusler compounds are mechanically stable. For three alloys, metallic behavior was recorded in spin-up channels, while indirect bandgaps of 0.385 eve, 0.489 eve and 0.321 eve were calculated in spin-down channels for Cr₂GdAl, Cr₂GdGa and Cr₂GdIn respectively. These compounds exhibit ferromagnetism with a magnetic moment of 13 μ_B, the integer magnetic moment confirm the half-metallic behavior of these compounds, characterized by 100% spin polarization at the Fermi level. Finally, we have studied the thermal properties by the quasi-harmonic Debye model incorporated in the GIBBS code, which takes into account the lattice vibrations, pressure, and temperature effects on structural parameters.

Within the framework of a modified potential cluster model with forbidden states, the behavior of the astrophysical S-factor for the radiative capture of a proton by ⁶Li to the ground state (GS) and first excited state (FES) of the ⁷Be nucleus was reconsidered at energies ranging from 30 keV to 5 MeV. It is shown that, using potentials consistent with the energies of the bound states and the values of the asymptotic normalization constants, it is possible to accurately describe the available experimental data for the astrophysical S-factor. A calculated value of 100 eV·b is obtained at zero energy. The reaction rate of the p⁶Li capture reaction is calculated at temperatures from 0.001 to 10T₉ based on theoretical cross sections. The calculated S-factor and reaction rate results are approximated by simple analytical expressions.

Researches on the flexoelectric effects have been attracted much attention in recent years. Large amounts of the existing contributions mainly concentrate on the experiments and the theorizations of flexoelectric materials. However, the improvement on the performance of flexoelectric materials cannot be studied in the view of the reliability size optimization theories. Based on this, the reliability optimization design of the multi-state flexoelectric structures is proposed through considering the parameter uncertainties. Meanwhile, the performance of the traditional deterministic optimization strategy is also employed to be compared with that of the reliability optimization design. Sequentially, the deterministic optimization model and the reliability optimization model of the electrical output responses are respectively established under multiple electrical states. Then the deterministic optimization strategy of the flexoelectric structures can be performed via the sequential quadratic programming (SQP), and the reliability optimization strategy can be calculated through using the double-layer method. Besides, the performance of the electrical output responses can be enhanced with the reliability optimization strategy. The results provide a reference selection for both of the design and the manufacture of flexoelectric structures, and lay a theoretical foundation for designing the devices in future.

Three nanocomposite films from the polyvinyl butyral (PVB) and Cu, Sn, and (Sn/Cu) were prepared utilizing the solution casting technique. The purpose of this study is to uncover influence of nanoparticles such as Cu, Sn, and (Sn/Cu) into structure and linear/nonlinear optical properties of nanocomposite films. Outcome nanocomposite films were identified via FTIR, XRD, SEM, TEM. Results cobfirmed the formation of nanoparticles from Sn, Cu, and (Sn/Cu) were formed into materix of PVB. FTIR showed that peaks of PVB were shifted noticeably compared to the neat PVB film. Results referred to the average particle size of Sn, Cu, and (Sn/Cu) were 15.7 ± 6.7, 18.2 ± 7.4, and 72.5 ± 13.5 nm, accordingly. The direct optical band gap energy of the PVB film was reduced from 5.84 eV to 5.45, 4.64, and 4.60 eV after adding Cu-NPs, Sn-NPs, and Sn/Cu-NPs, respectively. Conversely, the films’ band tail and carbon clusters were augmented after adding Cu-NPs, Sn-NPs, and Cu/Sn-NPs to the PVB matrix. Furthermore, results exposed the induced of Cu-NPs, Cu-NPs, and Sn/Cu-NPs on some optical features of PVB such as refractive index (n), dielectric constant (ε), and extinction coefficient (K). Incorporation of diverse nanoparticles also signifcantly affect optical conductivity (σ_opt), oscillation energy (E_o), dispersion energy (E_d), and average oscillator wavelength (λ_o). The studies were also executed on the susceptibility of non-linear optical and non-linear refractive index. Results confirm that adding Cu-NPs, Sn-NPs, and Cu/Sn-NPs to the PVB improves its nonlinear and linear optical properties. This renders nanocomposite films more useful for applications such as flexible electronic, nonlinear optics, and optical devices.

The nuclear ground-state features of waiting-point proton-rich nuclei with proton numbers ranging from 28 to 38 were examined using the relativistic mean-field (RMF) model with density-dependent meson-exchange (DDME2) interaction. The ground-state properties include quadrupole deformation parameter ((beta _2)), binding energy ((E_{b})), one proton (neutron) separation energy (S(_p), S(_n)), two proton (neutron) separation energy (S(_{2p}), S(_{2n})), and neutron skin thickness ((R_{np})). The (beta _{2}) values, computed using the RMF model and another set adopted from the finite range droplet model, were later employed in the proton-neutron quasi particle random phase approximation (pn-QRPA) model as an input parameter for the analysis of (beta)-decay properties, including the Gamow-Teller (GT) strength distributions, (beta)-decay half-lives, and stellar (beta ^{+})/electron capture rates for proton-rich nuclei ((^{52})Ni, (^{56})Zn, (^{58})Zn, (^{61})Ga, (^{62})Ge, (^{70})Kr, and (^{76})Sr). The calculated stellar rates changed marginally with a change in the deformation parameter. For core density (10^{7}) g/cm(^3) ((10^{11}) g/cm(^3)), the computed sum of (beta ^+) and electron capture rates increases up to 3 (1) orders of magnitude as the core temperature rises from 0.01 to 30 GK. Additionally, the present calculated rates were compared with earlier computations for nuclei (^{70})Kr and (^{76})Sr that were carried out using the independent particle model (IPM). The computed pn-QRPA (FRDM) rates are up to a factor of 5 larger than the IPM results in high temperature-density environments. The results of the present investigation may prove useful in simulating realistic nucleosynthesis models.

An exhaustive investigation of the electronic structure and material properties of magnesite (MgCO₃) has been conducted using first-principles computational methodologies. The lattice parameters, optical properties, mechanical properties, and vibrational modes of MgCO₃ under varying pressure conditions (0–120 GPa) were analyzed theoretically through density functional theory (DFT). A statistically significant correlation was observed between the simulated lattice constants and existing experimental and theoretical data. This work thoroughly evaluates the anisotropy of mechanical moduli by assessing elastic anisotropy indices and orientation-dependent variations in linear compressibility, including Young’s modulus, shear modulus, linear compressibility, and Poisson’s ratio. The calculated elastic constants and phonon dispersion relations confirm the mechanical and dynamic stability of MgCO₃ across the studied pressure range.

Cadmium Telluride (CdTe) solar cells are leading the way in efficient, cost-effective, and environmentally friendly solar energy conversion, with a favourable bandgap of 1.45 eV. However, the potential of zinc oxide (ZnO) as a buffer layer, its interaction with copper back contact, and the effect of its thickness on device performance have not been thoroughly investigated. To address this knowledge gap, we fabricated CdTe solar cells using vacuum-assisted chemical vapour deposition, incorporating ZnO as a coating layer. We varied the thickness of the ZnO layer at 0, 10, 20, and 30 nm, while all samples received a 50 nm copper back contact layer. Extensive characterization of CdTe solar cells revealed significant improvements with the addition of a ZnO coating and a copper back contact. Notably, the CdTe solar cell with a copper back contact and a 30 nm ZnO layer exhibited the best optical and electrical performance. X-ray diffraction analysis confirmed the presence of ZnO within the CdTe layer. The CdTe/30 nm ZnO/50 nm Cu configuration demonstrated an increased photocurrent density of 30 mA/cm², improved electrical conductivity of 3 × 10^–3 S/cm, good transmittance of 80%, optimal quantum efficiency of 85%, and a bandgap of 1.6 eV. These findings establish a connection between ZnO layer thickness and solar cell efficiency, providing valuable insights for optimizing CdTe-based photovoltaic devices.