East European Journal of Physics

Constrained Dynamics of Holographic Dark Energy in Modified f (R) Gravity

2025-09-08T04:07:37+00:00

In the present work, we examine the dynamical behaviour of holographic dark energy (HDE) within the framework of modified f(R) gravity in a hypersurface-homogeneous space-time. To explore the universe's evolutionary behaviour under the influence of dark energy, we consider both exponential and power-law expansions. The cosmic evolution is analysed using standard cosmological diagnostics, including the density parameter and equation of state (EoS) parameter along with the deceleration parameter. Furthermore, the statefinder diagnostic pair is tested to detect precisely different phases of the universe. The squared speed of sound parameter was used to incorporate the stability analysis for our models. This investigation links the principles of quantum gravity to cosmology, producing testable predictions for forthcoming research and illustrating that HDE functions as a credible alternative to ΛCDM.

FLRW model coupled with mass less scalar field in f(T) gravity-Two fluid scenario

2025-09-08T04:07:39+00:00

In this work, we investigate a cosmological model within the framework of modified teleparallel gravity, known as f(T) gravity, by considering a spatially flat Friedmann-Lemaître-Robertson-Walker (FLRW) Universe filled with two fluids-barotropic matter and a dark fluid-alongside a massless scalar field. We study an interacting case of the fluids, deriving exact solutions of the field equations under a time-dependent deceleration parameter scenario. The model demonstrates a viable cosmological sequence: early decelerating expansion followed by late-time acceleration. The torsion scalar T, its function f(T), and the scalar field all evolve dynamically, transitioning from dominant roles in the early Universe to diminished effects at late times. The dark fluid energy density remains nearly constant, supporting accelerated expansion, while the matter density decreases with cosmic time. The effective equation of state (EoS) parameter evolves from a matter-like behavior to negative values, suggesting a natural transition from matter domination to a dark energy-dominated phase. These results affirm that f(T) gravity coupled with a scalar field can explain cosmic acceleration and provide an alternative to the standard ΛCDM model without invoking exotic energy components.

Constraining the Hybrid Model for Investigating Holographic Dark Energy in Modified Gravity

2025-09-08T04:07:40+00:00

This study examines the dynamism of holographic dark energy (HDE) in the background of f(R) gravity through a hypersurface-homogeneous space-time setting. Looking at how HDE affects the advancement of the Universe, we used a simplified hybrid expansion law (HEL) to derive a precise solution to the associated field equations. The study begins with the analysis of certain kinematical and physical characteristics related to the model. We applied constraints to the outlined hybrid model using observational Hubble data (OHD), which consists of 32-point data sets, in order to evaluate the model's physical certainty and feasibility. In connection with the values of parameter that show up in our metric, three dynamically potential cosmological scenarios are outlined. Additionally, we examined various energy conditions (ECs) and discerned distinctive cosmic phases through the inspection of statefinder diagnostics and jerk parameter. The squared speed of sound parameter v_s² is used to ensure the model's stability. The study corroborates the Universe's cosmic acceleration, as our findings conform to prevailing observational data, offering viable projections for future research in substantiating HDE.

Spectra of Some Charmed Hadrons in a Non Relativistic Model

2025-09-08T04:07:43+00:00

In a non-relativistic framework the mass spectra of cĉ, cc, ccc and ccu systems are investigated. The potential consists of the Cornell potential along with a logarithmic correction term as suggested from lattice QCD. We analyze the S, P, and D wave charmonium states and, S and P wave cc diquark states and have compared them with existing results from experiments and other potential models. Using the quark-diquark model, we have evaluated the S-wave spectra of doubly charmed baryon Ξ⁺⁺_cc and the triply charmed baryon Ω_c_cc. These masses are compared with other theoretical studies.

Coupled-Channels Analysis and Optical Model Potential Extraction for Deuteron Scattering From 6Li to 208Pb

2025-09-08T04:07:44+00:00

Deuteron-nucleus elastic and inelastic scattering from ⁶Li to²⁰⁸Pb has been studied for incident energies ranging from 9.9 to 270 MeV. The main goal of this work is to study the effect of coupling the nuclear ground state to inelastic excitation channels on the energy dependence of optical model potential (OMP) parameters. Using the FRESCO and SFRESCO codes, we explicitly coupled the elastic channel to low-lying collective states and extracted OMP parameters through χ² minimization. The best-fit optical model parameters were obtained for elastic and inelastic angular distribution data. Our elastic and inelastic angular distribution fits show excellent agreement with the experimental data since more than one set of potential parameters can reproduce a given angular distribution data. When the ground state was coupled to the most important inelastic excitation channels the energy dependence of the OMP parameters was reduced. This is most obvious for optical model parameters whose value became almost constant when channel coupling was considered.

Event Fractions and Probabilities for 11Be + 209Bi Reaction in the Multibody 3-Stage Classical Molecular Dynamics Approach

2025-09-08T04:07:45+00:00

Unique structures that differ radically from ordinary nuclear matter have been demonstrated by Halo nuclei. Among other halo nuclei, the 11Be nucleus is one of the most studied halo nuclei, and it has a well-established one-neutron halo structure with neutron separation energy Sn = 0.501 MeV. We have studied ¹¹Be + ²⁰⁹Bi reaction in the multibody 3-Stage Classical Molecular Dynamics (3S-CMD) model, where 11Be is constructed as a cluster of tightly bound ¹⁰Be and one neutron. The separation between 10Be and neutron is adjusted to set the ion-ion potential between them equal to the experimental neutron separation energy. For this reaction, we have calculated fractions of events F(b) for given impact parameter, b and collision energy ECM and event probabilities P(ECM) by integrating F(b) over all the values of b ≤ b_max (b_max is impact parameter above which all trajectories results in scattering) for the given ECM. Here in present calculations, it is found that for near barrier energies, neutron transfer is significant for lower impact parameters, but at far above barrier energies, complete fusion dominates for lower impact parameters, while for slightly higher impact parameters, neutron transfer is accountable.

Modeling of the Characteristics of Electron Beams and Generated Photon Fluxes on the M-30 Microtron

2025-09-08T04:07:47+00:00

Ensuring optimization of the radiation treatment process of experimental samples at electron accelerators and effective prediction of the results of the interaction of electron beams with irradiation objects requires the most accurate information about the characteristics of the beams. The initial (primary) characteristics of accelerator electron beams during transportation to irradiation objects will change due to their interaction with the external environment (air). Thus, secondary particles are also generated - bremsstrahlung photons, which also interact with samples. The paper presents the results of studies on modeling the influence of air layers on the change in the initial characteristics of electron beams during their transportation to irradiation objects and on the parameters of the generated bremsstrahlung photon fluxes in the plane of placement of experimental samples. The studies used the Monte Carlo code ‒ GEANT4. The modeling was carried out for the electron accelerator of the IEP NAS of Ukraine - the M-30 microtron, taking into account its technical parameters. The results of studies of the characteristics (energy spectrum, their integral values, transverse distributions in the 10×10 cm plane) of the electron beam and secondary photons at the output of the electron accelerator are presented. The influence of the thicknesses of the air layers (0.1÷500 cm) between the electron output unit and the potential plane (100×100 cm) of the placement of experimental samples for irradiation on the characteristics of the primary electron beams and generated bremsstrahlung photons (for the energy range of 6÷20 MeV) is studied.

On The Features of Open Magnetoactive Waveguides Excitation

2025-09-08T04:07:49+00:00

It is shown that in the volume of an open waveguide, each electron – oscillator rotating in a constant magnetic field is capable of generating a TE wave, for which this waveguide is transparent. The generation efficiency is determined by the rate of electron injection and their longitudinal velocity along the waveguide axis. The field generation mode near the cutoff frequency with a low group velocity comparable with the longitudinal velocity of the injected electrons is selected. In this case, the transverse velocity of the electrons significantly exceeds their longitudinal velocity and the group velocity of the wave. In the absence of field reflection from the waveguide ends, each electron makes its contribution to the total radiation field, i.e. it can be considered that the field generation occurs in the superradiance mode. It is shown that the total field of the electron flow is capable of forming a resonator field consisting of two waves propagating towards each other due to even partial reflections from the waveguide ends. With a small reflection of the fields from the ends and a small drift velocity of the rotating electrons, the superradiance mode dominates, similar to the case of excitation of a completely open waveguide. In the case of a noticeable reflection of the fields from the ends of the system at a relatively high velocity of their longitudinal injection, the reflected fields significantly exceed the total field of the emitters and the traditional mode of waveguide resonator field generation is formed. The zones where either resonator field generation or generation under superradiance conditions dominate are presented on the plane "longitudinal motion velocity – reflection coefficient". Two cases are considered: when reflected waves are formed only due to reflection from the ends, and also when the effect of rotating electrons on reflected waves in the waveguide volume is taken into account. It is essential that the average amplitude of the total particle radiation field changes slightly for all considered generation modes. Resonance effects during reflection from the ends lead to a significant increase in the amplitude of the waveguide – resonator field.

Spatial Dynamics of a Radially Polarized Terahertz Laser Beam with a Phase Singularity

2025-09-08T04:07:51+00:00

Analytical expressions are obtained that describe the nonparaxial diffraction in free space of the TM₀₁ mode with radial polarization of the field of the dielectric waveguide resonator of a terahertz laser during its interaction with a spiral phase plate with different topological charge (n). The physical features of the obtained vortex beams during their propagation and tight focusing are studied by numerical simulation. The integral diffraction Rayleigh-Sommerfeld transforms are used to simulate the propagation and focusing of the obtained beams. In free space the use of the spiral phase plate at the waveguide output with a topological charge of n = 1 leads to a change in the transverse beam profile from annular to a beam that has a field maximum on the axis, and then for n = 2 again to annular. During focusing the transverse distribution of the total field intensity in the absence of a spiral phase plate has a ring structure. In this case there is a slight intensity on the axis due to the contribution of the longitudinal component of the field. The transverse profile of the beam changes in the same way as during its propagation when using a phase plate. In this case the phase front changes from spherical to spiral with the presence of two (n = 1) and four (n = 2) branching vortices.

Wave Propagation in Anisotropic Magnetically Quantized Ion Plasma with Trapped Electron and Positron

2025-09-08T04:07:52+00:00

This study examines the effects of magnetically quantized degenerate trapped electrons and positrons on small-amplitude ion acoustic shock waves (IAShWs) in a pair ion plasma using the Zakharov-Kuznetsov Burger (ZKB) equation. It focuses on how factors like magnetic quantization, degenerate temperature, normalized negative ions, electrons, positrons, anisotropic pressure, and other relevant physical parameters from an astrophysical plasma environment influence the propagation of IAShWs, particularly in the nonlinear regime. This research explores that there exist two distinct wave propagation modes—subsonic and supersonic which shows few distinct characteristics in different physical plasma environment of astrophysical origin. The results could aid in understanding the nonlinear dynamics and wave propagation characteristics in superdense plasmas found in white dwarfs and neutron stars, where the effects of trapped electrons and positrons, as well as ionic pressure anisotropy, are significant which is yet to be explored in detail.

Modelling of MHD Micropolar Nano Fluid Flow in an Inclined Porous Stenosed Artery with Dilatation

2025-09-08T04:07:54+00:00

In this paper, the impact of a magnetic field on blood flow with nanofluid particles through an inclined porous stenosed artery and dilatation was studied. Here blood is treated as micropolar fluid. The equations are solved by using Homotopy perturbation method [HPM] under the assumption of mild stenosis. The closed form solutions of velocity, temperature profile, and concentration distribution are obtained. The effects of pertinent parameters on flow phenomena have been observed and results are analyzed graphically. This study examines the impact of the magnetic parameter on flow characteristics and reveals that the presence of a magnetic field increases resistance to the flow while decreasing shear stress at the wall. A result is found that the flow resistance and shear stress at the wall decreased for heights of the stenosis dilatation. Additionally, the study finds that resistance to the flow increases and shear stress at the wall decreases with viscosity. The stream lines are drawn to examine the flow pattern and properties of momentum transfer.

Heat and Mass Transfer in Stratified MHD Flow Under an Inclined Magnetic Field

2025-09-08T04:07:55+00:00

This study investigates how thermal and mass stratification influence unsteady magnetohydrodynamic fluid flow through a permeable medium over an inclined parabolic plate when a slanted magnetic field is present. Laplace transform method is used to find closedform analytical benchmark solutions for flow governing equations. The study compares the results obtained from thermal and mass stratification with scenarios where both forms of stratification are not present. Non-stratified cases demonstrate elevated velocities in
comparison. Also the presence of both stratifications increases skin friction by 33.42%, the heat transfer rate by 97.54%, and the mass transfer rate by 36.91%. The biggest influence on fluid flow arises when the magnetic field is orthogonal to the flow direction. This study’s conclusions are pertinent for optimising fluid dynamics in engineering and environmental applications.

Effects of Radiation and Absorption on three dimensional Magnetohydrodynamic (MHD) Upper-Convected Maxwell Nano-fluid Flow

2025-09-08T04:07:56+00:00

The present paper deals with the study of the MHD upper-convected Maxwell nano-fluid flow through a bidirectional stretchable surface. The influence of heat absorption and thermal radiation has been studied. Governing non-linear partial differential equations, controlling the mass conservation, momentum conservation, energy conservation, and species concentration, are transformed into ordinary differential equations with the help of an appropriate similarity transformation, which are then solved numerically by using the bvp4c routine of MATLAB. The impact of various physical parameters on the velocity, temperature, and concentration distributions is described briefly with the help of graphs. The skin-friction, rate of heat and mass transfers at the plate are computed numerically and displayed through the table. Such a fluid flow problem may find applications in heat transfer mechanisms/devices.

MHD Hybrid Nanofluids Flow Through Porous Stretching Surface in the Presence of Thermal Radiation and Chemical Reaction

2025-09-08T04:07:57+00:00

This study investigates the convective transport of heat and mass in a magnetohydrodynamic (MHD) nanofluid flow over a permeable, electrically actuated stretching surface embedded in a porous medium. The analysis incorporates key physical effects including thermal radiation, heat generation, viscosity dissipation, and chemical reactions. The governing equations are formulated to account for the influence of porosity, magnetic fields, thermal and concentration gradients, as well as chemical kinetics. Special attention is given to the control of nanoparticle volume fraction at the boundary interface. Two nanofluid models – Copper–Water (Cu–H₂O) and Aluminum Oxide–Water (Al₂O₃–H₂O)—are considered to assess thermal performance. The nonlinear boundary value problem is solved numerically using a shooting technique combined with a fourth-order Runge–Kutta method. The results show excellent agreement with previously published data, validating the accuracy and robustness of the present model. These findings have potential applications in advanced heat transfer systems, such as cooling technologies and materials processing.

The Stagnation Point Flow of the MHD Casson Polymeric Nanofluid Flows Toward a Wavy Circular Cylinder Saturated with a Porous Medium under Convective Nield Conditions and Thermal Radiation

2025-09-08T04:07:59+00:00

This study conducts a thorough numerical investigation employing the bvp4c technique to delve into the stagnation-point flow of a magnetohydrodynamic (MHD) Casson polymeric nanofluid around a wavy circular porous cylinder. It takes into account activation energy and thermal radiation, emphasizing the significant impact of thermal radiation on fluid flow, concentration and temperature profiles. The effects of thermal radiation within the energy equation are carefully considered, along with convective Nield boundary conditions, enabling a comprehensive analysis. By introducing dimensionless variables, the study transforms the partial differential equation into ordinary equations, facilitating the application of the shooting scheme to approximate the solution. The meticulously examined results offer detailed insights into temperature, velocity and mass concentration profiles, highlighting the profound influence of thermal radiation on these parameters. Furthermore, a comprehensive graphical presentation of each engineering parameter is provided, offering a nuanced understanding of the intricate physical phenomena involved, with particular attention to the influence of thermal radiation.

Darcy-Forchheimer Flow of Oldroyd-B Nanofluid Over an Inclined Plate with Exothermic Chemical Reactions and Bayesian Neural Network Modelling

2025-09-08T04:08:00+00:00

This study investigates the steady, laminar motion of a non-Newtonian Oldroyd-B nanofluid over an inclined plate, integrating Buongiorno’s nanofluid model to account for Brownian motion and thermophoresis. The novel integration of couple stress and Forchheimer inertia in the analysis, coupled with advanced Bayesian-regularized ANN modelling, distinguishes this work. Governing equations are transformed using similarity variables and solved numerically via MATLAB’s bvp4c solver. The effects of couple stress, relaxation time, Forchheimer number, thermal radiation, thermophoresis, Brownian motion, and activation energy on velocity, temperature, and concentration profiles are systematically analyzed. Results reveal that couple stress and relaxation time reduce velocity, while thermal radiation and thermophoresis elevate temperature. Brownian motion decreases concentration, and activation energy influences both temperature and concentration oppositely. Multiple linear regression models quantify relationships between friction factor, Nusselt, and Sherwood numbers and key parameters, while a Bayesian-regularized artificial neural network (ANN) demonstrates high predictive accuracy (R-values ~1). It is noticed that increasing the couple stress parameter from 0.1 to 2.5 reduces friction factor by 59.8%, increasing the thermophoresis parameter from 0.1 to 2.5 decreases the Nusselt number by 7.8%, reflecting reduced heat transfer, and increasing the Brownian motion parameter from 0.1 to 2.5 reduces the mass transmission rate by 2.6%.

Influence of Lorentz Force and Arrhenius Activation Energy on Radiative Bio-Convective Micropolar Nanofluid Flow with Melting Heat Transfer over a Stretching Surface

2025-09-08T04:08:02+00:00

Novelty of this research is to explore an impact of Lorentz force, Arrhenius activation energy, and Conduction of Melting Heat on the micropolar fluid behaviour of steady radiative bio-convective micropolar nanofluid flow towards a stretchable surface. Using the standard similarity method, we have derived the equations of similarity for the relevant quantities of momentum, angular momentum, temperature, and concentration. The MATLAB tool 'bvp4c' is used to determine solutions to the transformed governing equations. Equations of similarity in four dimensions (momentum, angular momentum, temperature, and concentration) are numerically solved. We have examined, microrotation, velocity, concentration, temperature fields behavior for various parameters. Results show that the motile density of microorganisms decreases when the Peclet number and the microorganism concentration differential parameter are increased. Motility density increases as the Peclet number in microbial concentrations rises. Nanofluids are therefore appropriate as heat transfer fluids due to their surface cooling effect. The numerical scheme applied is validated by comparison with the previous numerical values.

Effects of Natural Convection and Radiation on MHD Stagnation Point Nano-Fluid Flow past a Stretchable Surface with Velocity Slip and Newtonian Heating

2025-09-08T04:08:04+00:00

MHD stagnation point natural convection flow of a viscous, incompressible, electrically conducting, and heat radiating nanofluid past a stretchy surface with velocity slip and Newtonian heating in the presence of a transverse magnetic field is examined. Governing nonlinear partial differential equations are solved with the help of Matlab’s bvp4c technique. To confirm robustness and accuracy of the result, the numerical findings in this study are compared with the existing literature, and they are found to be in good agreement. Effects of various parameters on velocity, temperature, and species concentration are computed and presented in the form of graphs whereas the effects on skin friction, the heat transfer rate and mass transfer rate are tabulated. As a result of enhanced thermal energy accumulation or diffusion, nanofluid temperature is increased by Brownian motion, thermophoretic diffusion, velocity slip, convective heating, nonlinear thermal radiation, and Prandtl number. Rate of heat transfer is getting enhanced by temperature ratio, convective heating, and thermal Grashof number due to increased thermal gradients and buoyancy-driven heat transport. Such nanofluid flows have the potential to be used in a number of heat transfer processes such as renewable energy devices including MHD power generators, etc.

Impact of Combined Chemical Reactions and Thermal Dispersion on Convective Flow in Hybrid Nanofluid Porous Medium

2025-09-08T04:08:06+00:00

The present study is characterized by numerical analysis concerning thermal dispersion's influence on heat and mass transfer flow towards a stretching plate in a saturated porous medium filled with Cu/Al₂O₃-water hybrid nanofluid, considering the presence of homogeneous (HOM)-heterogeneous (HET) chemical reactions. A new model of (HOM-HET) chemical reactions is constructed where the (HET) reactions occur on the surfaces of the solid matrix within the porous medium and the plate, following first-order kinetics. In contrast, the homogeneous (HOM) reaction takes place in the fluid phase and is described by isothermal cubic autocatalytic kinetics. The momentum, energy, and mass transfer phenomena are governed by a set of partial differential equations with appropriate similarity transformations that yield four coupled nonlinear ordinary differential equations. The resulting system of governing equations is solved numerically through a computationally efficient finite-difference scheme. The numerical results are validated through comparison with available data, showing good agreement. The numerical results demonstrate the influence of physical control parameters on the flow dynamics, thermal distribution, and solute concentration profiles. Furthermore, key solution characteristics, including the Nusselt number and skin friction coefficient, are tabulated.

Two-Phase Inclined MHD Blood Flow in Porous Tumor Region with Concentration and Volume Fraction

2025-09-08T04:08:07+00:00

There are different approaches for treating invasive and non-invasive tumors. The flowing fluid (blood) provides the required nutrients to the tumors and absorbs the suspensions. Drug delivery systems are dependent on the medium (flowing fluid) that carries the drugs. The blood vessels usually carry drugs to the targeted regions that treat the affected region. This situation varies the concentration of the tumor surrounding the medium. The system is monitored under a magnetic field that is applied at an angle ( The system of the blood flow surrounding a tumor is governed by partial differential equations (PDEs). The Governing equations are solved using the mathematical function PDEPE in MATLAB. The effects of different parameters, concentration parameters, inclined magnetic field, porosity, on fluid (blood) velocity, and medication (drug) velocity in the presence of volume fraction. Flow patterns so obtained show significant effects that help to treat the deceased regions clinically. The numerical results are interpreted through the graphs drawn.

Benjamin–-Feir Instability of Interfacial Gravity–Capillary Waves in a Two-Layer Fluid. Part I

2025-09-08T04:08:10+00:00

This study presents a detailed investigation of the modulational stability of interfacial wave packets in a two-layer inviscid incompressible fluid with finite layer thicknesses and interfacial surface tension. The stability analysis is carried out for a broad range of density ratios and geometric configurations, enabling the construction of stability diagrams in the $(\rho,k)$-plane, where $\rho$ is the density ratio and $k$ is the carrier wavenumber. The Benjamin-–Feir index is used as the stability criterion, and its interplay with the curvature of the dispersion relation is examined to determine the onset of modulational instability.
The topology of the stability diagrams reveals several characteristic structures: a localized \emph{loop} of stability within an instability zone, a global \emph{upper} stability domain, an elongated \emph{corridor} bounded by resonance and dispersion curves, and a degenerate \emph{cut} structure arising in strongly asymmetric configurations. Each of these structures is associated with a distinct physical mechanism involving the balance between focusing/defocusing nonlinearity and anomalous/normal dispersion.
Systematic variation of layer thicknesses allows us to track the formation, deformation, and disappearance of these regions, as well as their merging or segmentation due to resonance effects. Limiting cases of semi-infinite layers are analyzed to connect the results with known configurations, including the `half-space–layer', `layer–half-space', and `half-space–half-space' systems. The influence of symmetry and asymmetry in layer geometry is examined in detail, showing how it governs the arrangement and connectivity of stable and unstable regions in parameter space. The results provide a unified framework for interpreting modulational stability in layered fluids with interfacial tension, highlighting both global dispersion-controlled regimes and localized stability islands. This work constitutes Part~I of the study; Part~II will address the role of varying surface tension, which is expected to deform existing stability domains and modify the associated nonlinear–dispersive mechanisms.

Influence of Thermal Radiation Effect on MHD Mass Transfer Flow Past a Porous Vertical Plate in Presence of Constant Heat Flux

2025-09-25T13:38:49+00:00

In this work, we have undertaken to study heat and mass transfer in MHD convective flow past an infinite plate with porous media in existence of radiation, thermal diffusion effect and heat sink. A uniform strength of magnetic field was used transversely in the fluid region. The originality of this work is to examine the thermal diffusion effect on the flow incidents in case of heat sink or thermal radiation. The principal equations are solved by perturbation technique to get statements for velocity, temperature, and concentration fields. In this paper we also consider several physical quantities on the flow domain graphically as well as tabularly which have been studied previously by other researchers except few new cases like light velocity and temperature relationship from different sources such as density gradient effect which are being discussed herein for first time.

First-Principles Investigation of Semiconducting Cu2ZnSnX4 (X = S, Se) Eco-Friendly Materials for the Next Generation of Photovoltaic Applications

2025-09-08T04:08:16+00:00

The quaternary general form A₂BCX₄-based semiconducting materials with Kesterite-type structures are promising candidates for thin film-based solar cell devices. We examined the structural, electrical, optical, elastic, thermodynamic, and thermoelectric characteristics of Cu₂ZnSnX₄ (X = S, Se) using the FP-LAPW technique with an implanted Wien2k code. The Burke-Ernzerhof-generalized gradient approach (PBE-GGA) and Trans-Blaha modified Becke-johnson (TB-mBJ) are used to manage the exchange and correlation potentials. The results shows that Cu₂ZnSnS₄ and Cu₂ZnSnSe₄ compounds have stable structures with direct bands at 1.51 eV and 1.29 eV, respectively. The optical characteristics of these compounds were estimated using the dielectric function, allowing for an analysis of their reflectivity, refractive index, and absorption. Elastic parameters such as the Bulk, Young, Pugh, and Poisson ratios demonstrate that they are ductile and can be formed as thin films, a significant characteristic of Photovoltaic applications. Furthermore, we calculated various thermodynamic parameters entropy, and constant volume under pressure and temperature. We also determined the Cu₂ZnSnX₄(X = S, Se) exhibits good thermoelectric performance concerning the figure of merit at 300K which is nearly unity. According to our findings, these materials are viable candidates for future clean green solar energy applications.

Computer Simulation Study of Adsorption Processes of C20@Cn and C60@Cn (n=1-5) Carbon Clusters on Reconstructed Silicon Si(001) Surface

2025-09-08T04:08:17+00:00

In today's nanotechnology field, one of the requirements of the current direction is the ability of carbon nanostructures to have a strong bond with the substrate surface among the materials formed by the interaction of different substrates with the surface of various substrates. The study and identification of new structures with similar properties is one of the problems facing modern theoretical research. The current research work was carried out as one of the solutions to the above-mentioned problems, in which the adsorption of fullerene molecules on silicon substrates using the molecular dynamics (MD) method is a continuation of our work on the adsorption of fullerene C₂₀ and C₆₀ molecules on the surface of silicon Si(001) reconstructed by C_n (n=1-5) carbon clusters was simulated using the open source LAMMPS package based on the molecular dynamics method. Using the Tersoff interatomic potential, the interactions between the atoms of the substrate, Cn cluster, and fullerene molecules were expressed, and the adsorption energies of C₂₀@C_n and C₆₀@C_n carbon clusters, the length and nature of Si-C bonds, as well as stable adsorption states in trench and dimer rows were determined.

Energy and Angular Distributions of Scattered Ar+ Ions with a Blue Phosphorus Surface at Sliding Angles

2025-09-08T04:08:19+00:00

This article presents the theoretical results of energy and angular distributions of Ar⁺ions from the surface of blue phosphorus at a small value of the angle of incidence and initial energy receiving by computer simulation method. It is shown that at a small value of the initial energy of ions from the trajectory of scattered ions it is possible to obtain the general shape of the surface semichannel. Moreover, increasing the value of the initial energy makes it possible to obtain the full shape of the semichannel, as well as the shadow behind the semichannel, which provides information on the location of the atom of the second layer. It is established that in the energy distribution due to an increase in the value of the initial energy a multi-peak structure is formed. This makes it possible to determine the surface structure. The obtained angular distribution shows that there is a specular and multiple scattering of ions from the target.

Effect of Cobalt Doping on the Structural, Morphological, Optical, and Magnetic Properties of ZnO Thin Films Prepared by Ultrasonic Spray Pyrolysis

2025-09-08T04:08:20+00:00

Zinc-cobalt oxide (Zn_1−xCo_xO) thin films refer to a semiconductor material based on zinc oxide (ZnO) doped with cobalt (Co). This material is studied mainly for its modified magnetic, electronic and optical properties, particularly in the context of diluted magnetic semiconductors (DMS). This study analyzes the effect of cobalt doping on the structural optical, and magnetic properties of ZnO thin films, fabricated using alow-cost, scalable ultrasonic spray technique. Zinc-cobalt oxide (Zn_1−xCo_xO) thin films were successfully deposited on glass substrates using the ultrasonic spray pyrolysis technique at a substrate tem- perature of 450 ◦C, with cobalt doping concentrations of x = 0%, 1%, 3%, and 5%. X-ray diffraction (XRD) analysis revealed a hexagonal wurtzite structure for all samples, with no secondary phases, indicating effective incorporation of Co²⁺ ions into the ZnO lattice. Raman spectroscopy indicated the emergence of structural disorder and defect-related modes, consistent with the increase in Urbach energy. Scanning electron microscopy (SEM) showed granular surface morphologies, and a non-homogeneous surface pattern is visible on all samples. Atomic Force Microscopy (AFM) showed an increase in surface roughness and grain size with increasing doping concentration. Optical measurements confirmed high transmittance in the visible range and a gradual de- crease in optical band gap from 3.21 eV to 2.95 eV with increasing Co content. The spectroscopy, and vibrating sample magnetometer (VSM) revealed that all films are intrinsically ferromagnetic. The origin of the ferromagnetism was found to be an intrinsic property of the Co-doped ZnO thin films.

Structural, Electronic and Elastic Properties of Potassium Iodide, under Pressure: An Ab-Initio Analysis Study

2025-09-08T04:08:23+00:00

In this work, a recent version of the full potential linear muffin-tin orbitals (FP-LMTO) method was employed, using the local density approximation (LDA) within the framework of density functional theory (DFT). This approach was applied to study the structural, electronic and elastic behavior of the potassium iodide (KI) compound under pressure. The calculated structural parameters exhibit strong agreement with available theoretical and experimental data. The RS phase was identified as the most stable structure for KI material. The phase transition from NaCl-type (B1) to CsCl-type (B2) phase occurs at pressure of 1.633 GPa, which is quite consistent with the experimental values. Furthermore, the band structure of KI revealed a wide-band gap semiconductor behavior across all examined phases. The obtained bulk modulus values were relatively low, suggesting weak resistance to fracture. The elastic constants for KI in RS, CsCl, ZnS, HCP, and WZ structures were determined and found to meet Born’s stability conditions. We esteem, there is no values available in the literature on the elastic constants for KI in CsCl, ZnS and WZ phases. All analyzed structures displayed ductile characteristics and ionic bonding features. Additionally, anisotropic properties were observed in all phases. The compound’s stiffness was evaluated using Poisson’s ratio and Cauchy’s pressure. Results indicated that the CsCl phase is the most rigid among the studied configurations.

Statical Currents of p-Si–n-Si1-δSnδ–n+-Si1-δSnδ (0≤δ≤0.04)-Structures with Tin Quantum Dots

2025-09-08T04:08:26+00:00

In this work, the current-voltage characteristics of p-Si-n-Si_1-_δSn_δ structures at room temperature were investigated in order to clarify the role of injection effects in the formation of electrical properties of heterostructures obtained on the basis of the Si_1-_δSn_δ (0 ≤ δ ≤ 0.04) solid solution. It is shown that the sub linear sections observed on the current-voltage characteristics are well described within the framework of the theory of the injection depletion effect. The value of the parameter “a” was determined directly from the sub linear section of the current-voltage characteristic, which in the following allowed determining the concentration of deep impurities responsible for the appearance of the sub linear section. With this it was proved that the investigated structure can be considered as p-Si-n-Si_1-_δSn_δ–n⁺-Si_1-_δSn_δ (0 ≤ δ ≤ 0.04) - a junction with a high-resistance n-Si_1-_δSn_δ layer. An analysis of the results obtained allowed us to conclude that in this Si_1-_δSn_δ (0 ≤ δ ≤ 0.04) solid solution, scattering of charge carriers not only on complex complexes, but also on nanoformations plays a significant role in the formation of electro physical properties. Based on the results of the studies, it was concluded that the use of epitaxial films of Si_1-_δSn_δ (0 ≤ δ ≤ 0.04) solid solutions, obtained on silicon substrates, as promising materials, when developing diodes based on them, operating in the double injection mode.

The The Photoelectric Properties of n-Si–p-(Ge2)1-x-y(ZnSe)x(GaAs1-δBiδ)y Heterostructures

2025-09-08T04:08:30+00:00

In this paper, the photovoltaic properties of (Ge₂)_1-x-y(ZnSe)_x(GaAs_1-δBi_δ)_y solid solutions grown on silicon substrates are investigated. It is found that the solid solutions (Ge₂)_1-x-y(ZnSe)_x(GaAs_1-δBi_δ)_y possess selective photosensitivity due to the presence of ZnSe, Ge₂ and GaAs_1-δBi_δ components, as well as the difference in the ionisation energy of their covalent bonds. The photoconductivity mechanicms in n-Si-p-(Ge₂)_1-x-y(ZnSe)_x(GaAs_1-δBi_δ)_y heterostructures were analysed based on the E_i values that provided the best fit to the experimental spectrum and Gaussian approximation curves. Photopeaks corresponding to Gaussian curves at the energy levels 1.23 eV, 1.45 eV, 1.64 eV, 1.91 eV, 2.21 eV, and 2.45 eV were observed in the photon energy range: E_ph,₁ - 0.98÷1.75 eV, E_ph,2 - 1.01÷2.03 eV, E_ph,3 - 1.15÷2.28 eV, E_ph,4 - 1.34÷2.52 eV, E_ph,5 - 1.75÷2.71 eV and E_ph,6 - 2.1÷2.77 eV. The observation of intermediate states in the photosensitivity spectrum of this solid solution confirmed the presence of nano-objects formed on the basis of ZnSe and Ge₂ molecules, as well as GaAs_1-δBi_δ compounds in these films. It was found that solid solutions (Ge₂)_1-x-y(ZnSe)_x(GaAs_1-δBi_δ)_y have the potential to be used as selective photoactive materials operating in the ranges of infrared and visible radiation.

Surface Morphology and Roughness of Sulfur-Doped ZnO Thin Films: Analysis Based on Atomic Force Microscopy

2025-09-08T04:08:32+00:00

The surface morphology of undoped ZnO as well as 3 at. % sulfur-doped ZnO (ZnO:S) thin films were examined utilizing atomic force microscopy (AFM). Surface characteristics evaluations and comparisons were made based on 2D and 3D AFM images, line profile analyses, and roughness parameters; R_a, R_q, R_z, R_t R_sk, and R_ku. The undoped ZnO medium showed a smooth surface, with moderate height fluctuations and a comparatively narrow Gaussian-like height. On the other hand, ZnO:S film showed much higher surface roughness and topographical alternation with larger and more symmetrical height histograms. Both the R_q/R_a ratios for both started at around the theoretical Gaussian value (~1.25) with the skewness and kurtosis parameters showing distinctly different degrees of surface symmetry and texture. Sulfur incorporation was shown to change the grain morphology, to introduce peak-to-valley contrast and to increase the overall surface area. The morphological improvements further show that ZnO:S thin films could be more adequate for applications where high surface activity is essential, provided by gas sensing and catalysis. This study presents a quantitative and qualitative evaluation of the influence of sulfur doping on the surface morphology of ZnO at the nanoscale level.

Current Transfer Mechanism in a Thin-Based Heterosystem Based on A2B6 Compounds

2025-09-08T04:08:35+00:00

The possibility of fabricating a heterosystem based on А²В⁶ compounds with potential barriers (Au)CdS/Si/CdTe(Au) with a minimum density of surface states is presented, confirmed by measurements of the potential barrier height based on capacitance-voltage methods. Various exponential dependences of the current on the voltage at forward biases associated with a change in the kinetic parameters of the CdS/Si/CdTe structure base are determined, and it is revealed that at current densities of 2.1×10⁻⁷ ÷ 0.35×10⁻⁶ A/cm⁻² in the studied CdS/Si/CdTe structure, the current is limited by recombination in the space charge layer. It is shown that when a reverse bias is applied to the structure, the structure base is completely covered by the space charge accompanied by electron injection from the rear contact, which in turn determines the mechanism of current transfer of the structure.

Electrical, Optical, and Structural Properties of Silicon n+-p Structures

2025-09-08T04:08:37+00:00

The article investigates the structural, optical, and electrical properties of silicon n⁺-p structures. The experimental samples were made from high-resistance single-crystal silicon using two-stage phosphorus diffusion from solid-state planar sources. It was found that the introduction of phosphorus impurities with a concentration of 1.2∙10²⁰ cm^-3provokes the formation of dislocations with a surface density of 2∙10³-3∙10³ cm^-2due to the formation and relaxation of mechanical stresses. The formation of a lightening oxide film on the silicon surface reduces the reflection coefficient by 25%. However, the formation of an n⁺-layer reduces the transmittance coefficient of the structure. It was established from the voltage-current characteristics of the n⁺-p structure under forward and reverse voltage bias, that in the temperature range T = 295–346 K, these structures have rectifying properties. At room temperature, the height of the potential barrier is 0.6 eV and decreases with temperature and its height at 0 K is 1.32 еV. At low forward biases, the dominant mechanism of current transport in the structure is superbarrier emission. With an increase in forward voltage from 0.1 V to 0.6 V, the generation-recombination mechanism prevails, and with an increase in temperature, an increase in the contribution of tunnel current is observed. At low reverse voltages, the I-V characteristics of diodes are well described by the formula for the generation current. The depth of occurrence of donor energy levels, from which thermal generation of charge carriers occurs is 0.15 eV.

Effect of Dysprosium Atoms Introduced During the Growth Phase on the Formation of Radiation Defects in Silicon Crystals

2025-10-03T10:59:34+00:00

In this study, the formation and reduction mechanisms of radiation defects resulting from the incorporation of dysprosium (Dy) atoms during the growth process of silicon crystals (FZ) were investigated. Deep-level defects formed after doping n-type silicon with dysprosium and irradiating it with ⁶⁰Co γ-rays were analyzed using Deep Level Transient Spectroscopy (DLTS). The research revealed that in the presence of dysprosium, the concentration of defects such as A-center (vacancy-oxygen complex) and E-center (vacancy-phosphorus complex) decreased significantly - by 2-4 times - compared to control samples. EDS spectral analysis was conducted to determine the concentration of surface element atoms in the sample, which demonstrated that the Dy element was uniformly distributed on the silicon surface and present in sufficient concentration. These results substantiate that Dy atoms in silicon play a passivating role, inhibiting the kinetics of radiation defect formation, consequently increasing the radiation resistance of silicon-based structures.

Resistive Switching Behavior of SnO₂/ZnO Heterojunction Thin Films for Non-Volatile Memory Applications

2025-09-08T04:08:42+00:00

This study presents the fabrication and resistive switching (RS) performance of bilayer SnO₂/ZnO thin films deposited via ultrasonic spray pyrolysis on p-type silicon substrates. The heterostructures were post-annealed at 450°C to enhance crystallinity and interfacial contact. Electrical characterization using I–V measurements revealed clear bipolar RS behavior without the need for an initial forming process. The devices exhibited a stable high resistance state (HRS) and low resistance state (LRS) across multiple cycles, with an ON/OFF ratio exceeding 10². The switching mechanism is attributed to the formation and rupture of conductive filaments likely induced by oxygen vacancies at the SnO₂/ZnO interface. Bandgap estimation using Tauc plots showed values of approximately 3.17 eV and 3.41 eV for ZnO and SnO₂, respectively. These findings confirm the potential of SnO₂/ZnO heterojunctions as efficient materials for next-generation non-volatile memory applications.

Effect of Gate Oxide and Back Oxide Materials on Self-Heating Effect in FinFET

2025-09-08T04:08:44+00:00

The self-heating effect on the fin field effect transistor (FinFET) is investigated. The dependence of the lattice temperature in the channel center of the transistor on the thickness of the gate oxide, as well as the back oxide, is simulated. Different types of the most used oxide materials (SiO₂, HfO₂, and Si₃N₄) and their combination, SiO₂+Si₃N₄, are considered for gate and back oxides. 3D simulation is performed using Sentaurus TCAD. It is shown that the lattice temperature slowly and monotonically decreases with increasing gate oxide thickness. However, the lattice temperature is monotonically increasing with the thickness of the back oxide. This behavior of the lattice temperature depends on the relation between heat generation and dissipation rates in the transistor channel. A difference in the heat conductivity of the oxide materials explains the obtained behavior of the lattice temperature. Also, the lattice temperature dependence on the gate oxide thickness is explained by the increase in the contact area between the gate oxide and the gate with increasing gate oxide thickness. Besides this, it is accounted that the Joule heat generation rate depends on the drain current, which also depends on the oxide materials.

Impacts of Local Oxide Trapped Charge on Electrical and Capacitance Characteristics of SOI FinFet

2025-09-08T04:08:45+00:00

In this work, the influence of the local oxide trapped charge on the transfer Id-Vg characteristics and capacitance of the gatetoI. INTRODUCTION source (drain) connection of the silicon-on-insulator (SOI) structure-based FinFET is simulated. Id-Vg characteristics are simulated by using the drift-diffusion transport model. Capacitance-Voltage characteristics of the gate-to-source capacitance are simulated by using a small AC signal method. The Id-Vg characteristics and gate-to-source (gate-drain) capacitance are investigated at different linear sizes and positions of the local oxide trapped charge along the channel. The results of the simulation show that the threshold voltage monotonically decreases with an increase in the linear size of the local charge, and gate-to-source capacitance monotonically increases with an increase in the distance between the source-channel border and the center of the local charge.

Magnetic and Thermoelectric properties of RbCaYF(Y= C and N) Heusler alloys: Promising Candidates for Embedded Systems in Telecommunications

2025-09-08T04:08:47+00:00

On the basis of density functional theory, the structural, electronic, magnetic and thermoelectric properties of the d0 new quaternary Heusler alloys RbCaYF (Y= C and N) have been analyzed by means of first-principles calculations. The results predict a stable atomic arrangement in Y-type (III) phase with a ferromagnetic order. The two compounds were found to be half-metallic ferromagnets (HMFs) with an integer magnetic moment of 2µ_B for RbCaCF and 1µ_B for RbCaNF. The ferromagnetism observed is originated from the polarization of the p-Y orbitals with an sp-hybridization. In addition, RbCaCF and RbCaNF display large half metallic (HM) gaps of 0.879, 0.672 eV using Generalized Gradient Approximation (GGA), and 1.730, 1.934 eV with Generalized Gradient Approximation Modified Becke and Johnson (GGA-mBJ) respectively demonstrating stable half metallic features. Besides, thermoelectric properties were computed over a wide range of temperatures. The two Heusler alloys exhibit high values of electric conductivity and figure of merit especially at high temperatures. RbCaCF and RbCaNF d0 Heusler alloys present high spin polarization, robust half-metallicity and high thermoelectric coefficients, which makes them good candidates for spintronic and thermoelectric applications leading to promising enhancements for embedded systems in telecommunications.

Impact of Ruthenium Diffusion on the Electrical Properties of Thick Film Resistors

2025-09-08T04:08:49+00:00

The diffusion profile of the RuO₂ into silicate glass and the electrical resistance distribution across diffusion layer have been studied by beveled sample method and energy dispersion spectroscopy. The distribution of content of Ru atoms in the diffusion layer is described by the erfc(x) what means that the diffusion coefficient is independent of the content of Ru atoms. The correlation of the distribution of Ru atom content and the resistance distribution in the diffusion layer showed that it is the diffusion doping of glass that is responsible for the conductivity of thick-film resistors. Thickness of the diffusion layer is more than 100 μm while average distance between RuO₂ particles is about 0.5-2 μm. It means that all volume of the thick-film resistor comes conductive in firing process at 850°C in 10 minutes.

Simulation of Radiation-Induced Structural and Optical Modifications in ZnO:S/SI Thin Film Structures

2025-09-08T04:08:50+00:00

The research studied ZnO thin films containing 3 at.% sulphur (S) on silicon (1 μm) through Geant4 simulations for radiation analysis. Analysis of ZnO thin films (400 nm) doped with 3 at.% sulphur (S) on a 1 μm thick silicon substrate through Monte Carlo simulation platform Geant4 considered energy absorption together with particle penetration depth and ionization and secondary electron generation and optical property changes as the study examined different electron radiation energies from 3 keV to 10 keV. The ZnO:S layer absorbed most of the incoming electron energy in the 3-5 keV range which produced increases in defects near the surface while ionization occurred. When electrons used 9-10 keV energies they penetrated the full substrate layer which caused silicon to receive most of the energy absorption. The highest change in parameters occurred at the film-substrate junction when the energy reached 7 keV. All modeling findings demonstrated that the total absorbed energy together with secondary electron production and defect density reaching up to 10⁷ increased rapidly with electron energy acceleration. The decrease in optical properties occurs because defects exist at different depths while energy absorption takes place. Electrical and optical characteristics of ZnO:S/Si can be regulated through electron irradiation procedures according to this research. Results from this study will function as fundamentals for creating sensors and optoelectronic devices and protective coatings which operate effectively under high radiation conditions.

Impact of Boron Doping on Charge Distribution and Thermal Conductivity in Double-Walled Carbon Nanotubes

2025-09-08T04:08:52+00:00

This study investigates the effect of boron (B) doping on the electrical and thermal conductivity properties of single-walled carbon nanotubes (DWNTs) at various temperatures (300 K to 1500 K). The incorporation of boron atoms into DWNTs (5,5)@(10,10) was analyzed to explore how different doping levels (ρ%) influence the partial charge distribution and thermal conductivity. Our findings show that boron doping increases the partial charge within the nanotube structure, with a nonlinear increase in charge as the doping concentration rises from 0% to 10%. This is due to the lower electronegativity of boron, which introduces hole carriers and enhances p-type semiconductor behavior. However, at higher doping concentrations (above 5%), defects disrupt the π-electron network, reducing electrical conductivity. Thermal conductivity experiments indicate that the presence of boron leads to a decrease in heat transfer efficiency, especially at higher doping levels (>6%), where defect-induced phonon scattering significantly reduces the thermal conductivity. The results demonstrate that boron doping has a complex impact on the structural, electronic, and thermal properties of DWNTs, with temperature and doping concentration playing critical roles in determining performance.

The Spin-Polarized Properties of Ni-Doped ZnSe: First-Principles Simulation and Modelling

2025-09-08T04:08:54+00:00

This work delivers an in-depth ab initio investigation into the electronic and magnetic characteristics of ZnSe systems doped with nickel, evaluated at two distinct impurity levels: 6.25% and 12.5%. The analysis is grounded in density functional theory (DFT), employing the local spin density approximation (LSDA) framework, further refined with Hubbard U corrections to effectively capture the pronounced electron correlation effects typical of transition metal d-electrons. The incorporation of Ni into the ZnSe matrix significantly modifies the electronic structure, leading to half-metallic behavior and pronounced spin polarization. Total magnetic moments of 4.0 µ_B per supercell were observed. Furthermore, energy comparisons between ferromagnetic and antiferromagnetic configurations confirmed that the ferromagnetic phase is more energetically stable. These results highlight the potential of Ni-doped ZnSe in spintronic applications where controlled magnetic and electronic properties are crucial.

Effect of Temperature on the Current-Voltage Characteristics of n GaAs p-(ZnSe)1–x–y(Ge2)x(GaAs1–δBiδ)y Heterostructures

2025-09-08T04:08:55+00:00

This paper investigates the electrophysical properties of n-GaAs-p-(ZnSe)_1–x–y(Ge₂)_x(GaAs_1–_δBi_δ)_y heterostructures at different temperatures. The epitaxial n-GaAs-p-(ZnSe)_1–x–y(Ge₂)_x(GaAs_1–_δBi_δ)_y grown on GaAs substrates showed p-type conductivity, and their resistivity (5 Ω·cm), charge carrier concentration (ρ = 1.5-10¹⁶ cm^-³) and carrier mobility (μ = 300 cm²/V·s) were determined by Hall method. Experimental values of the mobility of the main charge carriers allowed us to determine the mobility of the non-main charge carriers, which amounted to (μ = 1890 cm²/V·s) by means of theoretical calculations. When a voltage in the range of 0.1 to 3 V was applied to the n-GaAs-p-(ZnSe)_1-x-y(Ge₂)_x(GaAs_1-_δBi_δ)_y heterostructures, the rectification ratio k = J_dir/J_rev varied between 2000 and 2500, and it was found that the density of surface states at the p-n junction interface remained low. In the current-voltage (I–V) characteristics of the n-GaAs-p-(ZnSe)_1-x-y(Ge₂)_x(GaAs_1-_δBi_δ)_y heterostructure, a quadratic dependence of J ~ V² was revealed, and this dependence does not change with increasing temperature in the transition to regions with a sharp increase in current. Analysis of these regions of the volt-ampere characteristic showed that the mechanism of current flow is determined by the direct drift of charge carriers. It was proposed to use n-GaAs-p-(ZnSe)_1-x-y(Ge₂)_x(GaAs_1-_δBi_δ)_y heterostructures in voltage amplifiers, constant voltage converters, as well as in electronic and thermoelectronic devices

Growth of BaZrS3 Chalcogenide Perovskite Thin Films Without Post Annealing

2025-09-08T04:08:56+00:00

Tandem solar cells based on hybrid organic–inorganic metal halide perovskites have achieved power conversion efficiencies of up to 28%. However, issues related to long-term stability and lead (Pb) toxicity have prompted the search for earth-abundant, chemically stable, and non-toxic alternatives. In this work, we report the first vacuum evaporation synthesis of BaZrS₃ (barium zirconium sulfide) thin films at a substrate temperature of 550 °C. The resulting films exhibit near-stoichiometric Ba:Zr ratios and strong light absorption, with absorption coefficients exceeding 10⁵ cm⁻¹ near 1.9 eV. Under controlled conditions, a baseline oxygen content of 4–6% was consistently observed. The absence of an additional sulfurization step markedly increased the resistance of the thin film and suppressed the dark current by approximately three orders of magnitude, indicating a substantial reduction in carrier density likely resulting from a decreased concentration of sulfur vacancies. These findings highlight the potential of BaZrS₃ as a stable, lead-free absorber for next-generation photovoltaics.

Tunable Matching Layer Method for Identifying Impurities on Liquids at Microwaves

2025-09-08T04:08:57+00:00

The aim of the work is to develop a method for contactless identifying of impurity concentration in liquids of a given type in the microwave frequencies. The work presents the theoretical analysis of the novel method for identifying impurities in liquids at microwave frequencies, based on the use of a tunable matching layer (a dielectric layer of variable thickness). To find the reflection coefficient of an electromagnetic wave from the layered structure, a standard technique consisting of determining the electromagnetic fields in each region and imposing continuity conditions for the field components at each boundary of the layer was used. Numerical estimations of the method’s sensitivity are provided using the example of determining ethanol impurity concentrations in water. The results are compared with experimental data reported in other publications. It has been shown that this method has a high sensitivity to impurity concentration.

Semi-Empirical Models of Electron Beam Control for Radiation Sterilization

2025-09-08T04:08:59+00:00

To carry out radiation sterilization, one needs to determine the permissible irradiation modes, which is carried out using computer dosimetry methods. Nowadays, the choice of optimal irradiation modes can be based on the models of the depth-dose curve at different incidence angles of the electron beam on the layer of matter. In the present paper, the distribution of transferred energy in the volume of the target initiated by the normal incidence of a point beam of radiation on the surface of a semi-infinite medium (Dose-Map object) is used to develop such models. Semi-empirical models of the Dose-Map object are designed based on two assumptions. One is that the target has axial symmetry relative to the direction of the radiation particle incidence on the target. The second is that the dose spatial distribution is uniform or normal (Gaussian distribution) in the cross-sections of the Dose-Map object at all depths. For a two-parameter approximation of the Dose-Map object, three-dimensional geometric figures are suggested, which surfaces are formed by rotating the plots of power functions around the abscissa axis. Semi-empirical models are developed based on the assumption that the parameters of the Dose-Map object in its eigen coordinate system do not change when the beam incidence angle changes. Expressions are obtained for calculating the depth-dose curves from radiation incident on the target at an angle θ in the form of an integral transformation of the depth-dose curve for normal incidence of the radiation beam on the target. Software has been developed for calculating depth-dose curves in a semi-infinite medium under uniform irradiation by an electron beam. The implemented algorithms for calculating the depth-dose curves from an electron beam incident on the target at the angle θ are tested. Satisfactory agreement is established between the results obtained using the developed semi-empirical models and the results of Monte Carlo modeling of the depth-dose curves at different incidence angles of the electron beam on the target. Good agreement is established between the results obtained using the semi-empirical model "Cone" and the results obtained using the developed two-parameter semi-empirical models SEM2U and SEM2N. The capabilities of the developed two-parameter models for a more complete description of the technological characteristics of the radiation sterilization process are investigated using the numerical methods. Examples are provided where the developed two-parameter models allow for the simultaneous description of two technological characteristics of the two-sided irradiation process: the optimal target thickness and the dose uniformity ratio (DUR) in the target. Consistent data on these characteristics allow choosing optimal modes of electron beam irradiation during radiation sterilization in a reasonable manner. The possibilities of using the approach suggested in the present paper for developing a set of semi-empirical models of computer dosimetry of irradiation processes in radiation technologies are noted.

Justification of a High-Energy Regime for Water Disinfection by an Electron Beam

2025-09-08T04:09:02+00:00

The challenge of providing safe and clean drinking water requires reliable disinfection methods. Electron beam processing is a promising technology, but its industrial application is often limited by regulatory constraints, which typically cap the electron energy at 10 MeV to prevent induced radioactivity. This paper presents a theoretical justification for the radiological safety of using a higher, sub-threshold energy regime. This paper proposes operating in the 10–15.6 MeV range (using 14.9 MeV as a case study) and demonstrate that this approach allows for the treatment of significantly thicker water layers compared to the standard 10 MeV regime, while ensuring radiological safety. A comprehensive numerical model was used to simulate the process, calculating the bremsstrahlung photon spectrum and the induced activity from potential photonuclear reactions. A quantitative analysis of induced activity was performed for the main components of water (¹⁶O, ²H) and typical trace impurities according to Ukrainian standards (DSanPiN 2.2.4-171-10). The analysis proves that the induced radioactivity is negligible. The primary activation channel on oxygen is energetically forbidden, and the activity from trace elements is short-lived and falls far below the intervention levels set by Ukrainian radiation safety norms (NRBU-97). This work provides a strong physics-based rationale that a high-energy, sub-threshold regime is radiologically safe, which allows for a reconsideration of existing energy limitations in the design of electron beam water treatment facilities.

Analysis of Temperature-Dependent Surface Properties in the Ni/SiO2/Si System During Electron Beam Deposition

2025-09-08T04:09:05+00:00

In this study, we investigated the morphological properties of nickel (Ni) island-shaped thin films formed on a SiO_x/Si substrate using the electron beam evaporation method. The morphology was examined using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). SEM images were analyzed with the help of ImageJ software to determine the size, density, distribution, and coverage ratio of the islands. The results showed a strong dependence of island morphology on substrate temperature: at 20 °C, the islands had an irregular shape with a density of 103 µm⁻², while at 250 °C and 500 °C, the islands became more spherical in shape, and their densities increased to 751.8 and 1212.4 µm⁻², respectively. AFM analysis confirmed the uniform distribution of the islands and their average height (15.4 nm). EDS analysis revealed the presence and uniform distribution of Si, O, and Ni elements on the surface. These findings confirm that substrate temperature is a critical factor in the island formation process.

Investigation of the Behavior of Nickel Impurity Atoms in the Silicon Lattice Based on First Principles

2025-09-08T04:09:08+00:00

This work presents a comprehensive theoretical and experimental study of the behavior of nickel impurity atoms in the silicon crystal lattice. The focus is on analyzing diffusion mechanisms, the energetic characteristics of interstitial nickel atoms, their interaction with defects and other impurities, as well as the formation of stable clusters within the crystal volume. First-principles quantum mechanical modeling was employed using the QuantumATK software, applying the Linear Combination of Atomic Orbitals (LCAO) method and the Local Density Approximation (LDA) exchange-correlation functional. Special attention was given to calculating the binding energy of nickel atoms in interstitial sites and estimating the activation energy for their migration along various crystallographic directions ([100] and [010]). The modeling results revealed that nickel atoms predominantly diffuse in interstitial positions with an activation energy around 0.31 eV, which aligns well with previously reported experimental data. It was found that interactions of nickel with oxygen, carbon impurities, and point defects have a minimal impact on diffusion processes. However, interactions with vacancies lead to the formation of stable nickel silicides and cause an increased concentration of nickel near the surface. The experimental part of the study confirmed the formation of nickel clusters under high-temperature treatments. Scanning Electron Microscopy (SEM), Secondary Ion Mass Spectrometry (SIMS), and Infrared (IR) microscopy revealed a high density and uniform distribution of clusters throughout the crystal volume. Cluster sizes ranged from 20 to 100 nm, with concentrations reaching approximately 10¹⁰ cm^-3. These findings demonstrate that nickel acts as an effective gettering impurity, enhancing the electrophysical properties of silicon. The results provide valuable insights for optimizing the fabrication processes of high-efficiency silicon solar cells and microelectronic devices.

Investigation of the Influence of Nickel on the Behavior of Thermal Donors in Silicon

2025-09-08T04:09:12+00:00

The experimental part of the study confirmed the formation of nickel clusters under high-temperature treatments. Scanning Electron Microscopy (SEM), Secondary Ion Mass Spectrometry (SIMS), and Infrared (IR) microscopy revealed a high density and uniform distribution of clusters throughout the crystal volume. Cluster sizes ranged from 20 to 100 nm, with concentrations reaching approximately 10¹⁰ cm^-3. These findings demonstrate that nickel acts as an effective gettering impurity, enhancing the electrophysical properties of silicon. The results provide valuable insights for optimizing the fabrication processes of high-efficiency silicon solar cells and microelectronic devices.

Influence of an Additional P3HT Layer on the Performance of P3HT: IC60BA Polymer Solar Cell

2025-09-08T04:09:14+00:00

A simulation study utilizing SCAPS 1-D software was conducted to explore the effects of an additional P3HT (Poly 3-hexylthiophene) layer on the performance of bulk heterojunction polymer solar cells, specifically with the active layer P3HT: IC₆₀BA. The investigated cell structure is ITO/PEDOT:PSS/P3HT/P3HT:IC₆₀BA/ZnO NPs/Al. Following the standardization of the software, we determined the optimal parameters of the solar cell structure by analyzing various factors influencing cell performance across different layers. Subsequently, after optimizing the structure, the power conversion efficiency (PCE) improved significantly, rising from 5.18% without additional layer to 15.26% with additional layer.

A 31% Efficient CIGS-Based Solar Cell Using Spiro Material as a Buffer Layer: Numerical Simulation

2025-09-08T04:09:16+00:00

This study investigates the potential boost of (Cu(In,Ga)Se2) based solar cells through numerical simulations using SCAPS-1D software to optimize their performance. Various parameters were analyzed, including the thickness, acceptor concentration, and band gap of the CIGSe active layer, as well as the donor concentration and thickness of the ZrS₂ buffer layer. The impact of operating temperature was also considered. The optimized output characteristics of the proposed cell design include a V_OC of 1.13V, J_SC of 32.61mA/cm², FF of 89.12, and a PCE of 32.91. These findings can aid in advancing the development of high-efficiency CIGSe-based thin-film solar cells.

Influence of Fluorosubstitution on the Heat Capacity of Aliphatic Alcohols

2025-09-08T04:09:17+00:00

In this paper, the principle of corresponding states was used when conducting a comparative analysis of the temperature dependences of the isobaric heat capacity of aliphatic alcohols and their fluorosubstituted analogues. For the heat capacity, both literature experimental data and simulated data, obtained using artificial neural networks, were applied. The isobaric heat capacity for the aliphatic alcohols in the absolute values in a wide temperature range at constant pressure is smaller than that for the corresponding fluorosubstituted analogues. The comparison of the heat capacity data on the aliphatic alcohols and their fluorosubstituted analogues with the heat capacity of water, for which there is a hydrogen bond network, and comparison of the corresponding data with the heat capacity of hydrogen peroxide, where there are hydrogen bonds, but the network is absent, indicates that the change in the physical properties of alcohols upon fluorosubstitution is associated with the hydrogen bond density.

Dielectric Relaxation and Molecular Interactions in Acetic Acid

2025-09-08T04:09:19+00:00

This article presents the results of measurements of the dielectric coefficients of acetic acid and its solutions. Measurements were carried out at wavelength λ = 40.0; 30.0; 20.0; 10.0; 6.4; 4.4; 2.1; 1.2; and in the temperature range 20 ÷ 50°C. Models of molecular clustering in liquid acetic acid were studied based on analysis of the dielectric absorption spectrum. The results of a study of the radio frequency absorption spectrum of acetic acid indicate the presence of two polymorphic forms of this compound. The characteristic temperature dependences of the dielectric constant ε' of acetic acid have been determined, from which two isothermal rotational transitions are clearly visible. The first - at the melting point - is accompanied by a sharp decrease in the number of dielectrically active units. The second, at a temperature below the melting point, leads to dielectric constant ε' values close to the high frequency (HF) limit of the total orientation contribution for microwave absorption in liquid acid. At temperatures above the first and below the second transitions, the values of the dielectric constant ε' do not depend on the frequency of the electromagnetic wave; on the contrary, pronounced dispersion is observed in the interval between two transitions.

Polyphenol Interactions with Amyloid Fibrils: A Molecular Docking Study

2025-09-08T04:09:20+00:00

Polyphenols, a versatile group of naturally occurring compounds with many favorable biological properties currently attract increasing research interest in the context of their ability to inhibit the formation and to destabilize special protein aggregates, amyloid fibrils, associated with a number of human diseases. In the present study the molecular docking technique was used to gain insights into molecular details of the interactions between polyphenolic compounds such as quercetin, curcumin, resveratrol, sesamin, salicylic and gallic acids with the mature amyloid fibrils from Abeta peptide, islet amyloid polypeptide, insulin, apolipoprotein A-I and apolipoprotein A-II. All examined polyphenols displayed the highest binding affinities for amyloid fibrils from apolipoprotein A-II and insulin, while the lowest affinities were observed for the fibrillar apolipoprotein A-I. The hydrophobicity/hydrophilicity analysis of amino acid composition of the binding sites showed that hydrophobic and neutral residues play a predominant role in the polyphenol complexation with amyloid fibrils from apolipoprotein A-I, apolipoprotein A-II and insulin, the basic residues essentially contribute to polyphenol association with fibrillar Abeta and islet amyloid polypeptides, while the involvement of acidic residues was revealed only for the complexes sesamin + apolipoprotein A-I / Abeta fibrils and curcumin keto + insulin fibrils. The results obtained may prove useful in the development of novel polyphenol-based anti-amyloid strategies.

Computational Study of Drug Delivery Systems with Radionuclide and Fluorescence Imaging Modalities. IV. Doxorubicin Delivery Systems Based on Albumin and Hemoglobin

2025-10-08T20:34:11+00:00

The development of multifunctional drug delivery systems that integrate therapeutic and diagnostic capabilities remains a major challenge in oncology. In the present work we investigated hybrid carriers composed of human serum albumin and hemoglobin (HSA-Hb) for doxorubicin (DOX) delivery combined with radionuclide and fluorescence imaging. Using molecular docking simulations, we systematically evaluated the interactions of HSA-Hb assemblies with twelve technetium-99m (^99mTc)-labeled radiopharmaceuticals, DOX, and four near-infrared (NIR) dyes. The results revealed that hemoglobin markedly expands the binding landscape, providing exclusive and high-affinity sites for several ^99mTc complexes (notably TcMEB and TcDIS), while also serving as the primary scaffold for DOX and NIR dyes. Two distinct DOX-binding pockets were identified within Hb subunits, suggesting enhanced drug stability and potential responsiveness to tumor hypoxia. Fluorescent dyes, including methylene blue, indocyanine green, AK7-5, and SQ1, exhibited preferential binding to Hb with affinities higher than those observed for albumin, indicating superior suitability for optical imaging. Importantly, the partitioning of radiopharmaceuticals to albumin and therapeutic/imaging ligands to hemoglobin reduced binding competition and enabled the simultaneous integration of multimodal functions within a single construct. These findings highlight HSA-Hb nanocarriers as promising candidates for next-generation theranostic platforms, combining efficient DOX delivery with non-invasive radionuclide and fluorescence monitoring.

Influence of Radio Frequency Magnetron Sputtering Parameters on the Structure and Performance of Al and Al2O3 Thin Films

2025-09-08T04:09:25+00:00

In this work, the structural, morphological and optical properties of aluminum (Al) and aluminum oxide (Al₂O₃) thin films deposited by radio-frequency (RF) magnetron sputtering were studied. The films were grown using a high–purity Al target in controlled atmospheres containing varying flows of argon (Ar) and oxygen (O₂). Particular attention was given to how the target-substrate distance and the Ar/O₂ flow ratios influence the films’ structural properties, surface features, and optical response. Characterization techniques included X-ray diffraction (XRD) for phase identification and crystallite size estimation, Atomic Force Microscopy (AFM) for surface morphology and roughness analysis, and UV–Vis Spectroscopy for optical transmittance measurements. The results showed that reducing the target-substrate distance led to films with increased surface roughness, thickness, grain size and crystallite size, likely due to enhanced energetic bombardment and adatom mobility. Optical measurements revealed that Al₂O₃ films grown at higher O₂ flow rates (around 5 sccm) were highly transparent, exhibiting transmittance values close to 100% across the UV-visible range (190-900 nm). In contrast, films deposited under low O₂ flow conditions (0.6-1.4 sccm) were nearly opaque, indicating incomplete oxidation or metallic behavior. The XRD analysis revealed that higher O₂flows tended to suppress crystallinity, resulting in amorphous Al₂O₃ films, while lower flows preserved some degree of crystalline order. Additionally, increasing the Ar flow rate during deposition promoted films growth, as evidenced by increased film thickness, which may be attributed to enhanced sputtering efficiency and target atom flux. These findings highlight the critical role of deposition parameters in tailoring the properties of Al-based thin films for optical and electronic applications.

Exploring plane symmetric space-time in f(R) modified gravitational theory

2025-09-08T04:09:29+00:00

This paper investigates a plane-symmetric cosmological model (PSCM) in the context of modified f(R) gravity theory, incorporating both vacuum and non-vacuum scenarios. A perfect fluid is assumed as the matter source. To obtain the solutions, we consider the premise of constant scalar curvature. By applying the conservation law for Einstein's field equation, T^ij_;j, and the power-law assumption, we retrieve some well-known solutions. We solved the field equations by making a specific assumption that involved a transformation A²B=U . This study explores the physical and kinematic characteristics of specific cosmological models, along with an examination of the statefinder diagnostic—a key tool for analysing the universe’s evolutionary trajectory. The work provides important insights into the behaviour of anisotropic models within the context of modified f(R) gravity. It highlights the interplay between matter distribution and spacetime geometry, particularly emphasizing how assuming a constant scalar curvature aids in simplifying and solving the corresponding field equations. The resulting solutions enhance our understanding of cosmic evolution governed by modified f(R) gravity.

Fluorescent Detection of Heavy Metal Ions Using Benzanthrone Dye

2025-09-08T04:09:32+00:00

The development of sensitive, low-cost, and biocompatible sensors for detecting toxic heavy metals remains a pressing challenge in environmental monitoring. Protein-based nanostructures present unique opportunities in this regard. Coupliang amyloid fibrils with amyloid-sensitive fluorescent dyes, which exhibit distinct spectral responses upon binding to amyloid structures and in the presence of metal ions, may lead to a promising sensing platform. In this study, the benzanthrone derivative ABM was examined as a fluorescent probe for detecting heavy metal ions in aqueous solutions and in the presence of β- β-lactoglobulin amyloid fibrils (β-lgf). In water, benzanthrone dye shows a broad emission spectrum dominated by a band at 690 nm. Binding to β- lgf produces a substantial increase in fluorescence intensity and a ~65 nm hypsochromic shift, indicating dye partitioning into the fibrillar hydrophobic environment. In aqueous solutions, ABM responds to heavy metals with characteristic spectral changes: Pb ²⁺ and Ni ²⁺ decrease the 690 nm emission band and generate a 560 nm band, while Cu ²⁺ and Zn ²⁺ cause complete quenching of the 690 nm emission with the appearance of a prominent 560 nm maximum, consistent with the formation of metal–ligand charge–transfer complexes. In the fibrillar environment, ABM displays a dominant emission at 560 nm; addition of heavy metals modulates the intensity and shape of this band in an ion-specific manner. Deconvolution of the emission spectra revealed two spectral components, whose amplitudes and shape descriptors were selectively altered by Ni ²⁺ and Cu ²⁺, while Zn ²⁺ and Pb ²⁺ had lesser effects. These findings demonstrate that ABM fluorescence reports sensitively on the strength and specificity of heavy metal interactions with amyloid fibrils, supporting its potential as an optical sensor for probing protein–metal systems.