East European Journal of Physics

Kaluza-Klein FRW Renyi Holographic Dark Energy model in Scalar-Tensor Theory of Gravitation

Y. Sobhanbabu — 2024-09-02

This work examines the dark energy phenomenon by studying the Renyi Holographic Dark Energy (RHDE) and pressure-less Dark Matter (DM) within the frame-work of Saez-Ballester (SB) scalar-tensor theory of gravitation(Phys. Lett. A113, 467:1986). To achieve a solution, we consider the viable deceleration parameter (DP), which contributes to the average scale factor a=e^{(1/γ)[ √ (2γt+c1)]}, where γ, and c₁ are respectively arbitrary, and integration constants. We have derived the field equations of SB scalar-tensor theory of gravity with the help of Kaluza-Klein FRW Universe. We have investigated cosmological parameters namely, DP (q), energy densities (ρ_M) and (ρ_R) of DM and RHDE, scalar field (ϕ), and equation of state parameter (ω_R). The physical debate of these cosmological parameters are investigated through graphical presentation. Moreover, the stability of the model are studied through squared sound speed (v_s²) and the well-known cosmological plane ω_R- ω'_Rand all energy conditions and also, density parameters are analyzed through graphical representation for our model.

Constraining Logarithmic f(R, T) Model Using Dark Energy Density Parameter Ω_Λ and Hubble parameter H_0

Biswajit Deb — 2024-09-02

Of many extended theories of gravity, f(R, T) gravity has gained reasonable interest in recent times as it provides interesting results in cosmology. Logarithmic corrections in modified theories of gravity have been studied extensively. In this work, we considered logarithmic correction to the trace term T and took the functional form as f(R, T) = R+16πGαlnT where α is a free parameter. The free parameter is constrained using dark energy density parameter Ω_Λ and Hubble parameter H₀. The lower bound is found to be α ≥ −9.85×10⁻²⁹. The cosmological implications are also studied.

Five-Dimensional Strange Quark Bianchi Type-I Cosmological Model in The Framework of Saez Ballester Theory of Gravity

Mahesh Netnaskar — 2024-09-02

In this paper, we have constructed a five-dimensional Bianchi type I cosmological model with strange quark matter in the context of Saez-Ballester theory of gravity. We have discussed a five-dimensional cosmological model by using the special rule of variation for the Hubble parameter in the shape of H = Da^-1 and the equation of state for strange quark matter. Two different models for n ≠ 0 and n = 0 have been discussed. Also, the accelerated expansion of the Universe has been discussed by using various physical parameters and its graphical representation.

LRS Bianchi Cosmological Model in Saez-Ballester Theory of Gravity with Time Varying Cosmological Constant

Chandra Rekha Mahanta — 2024-09-02

The present work deals with the study of a locally rotationally symmetric (LRS) Bianchi type-I cosmological model in the framework of a scalar-tensor theory of gravity formulated by Saez and Ballester with time varying cosmological constant. To obtain the explicit solutions of the Saez-Ballester field equations we assume the average scale factor to obey a power law expansion and the cosmological constant to be proportional to the energy density of the cosmic fluid. The dynamical behaviour of relevant cosmological parameters including the Hubble parameter, the deceleration parameter, the energy density, the pressure, the equation of state parameter, the cosmological constant, the shear scalar, the expansion scalar etc. are investigated graphically by examining their evolution versus the redshift parameter. The validation of the four energy conditions are also checked. We find the outcomes of the constructed model to be in good agreement with the recent observational data.

Anisotropic Cosmological Model with SQM in f(R, Lm) Gravity

Pravin Bolke — 2024-09-02

A locally rotationally symmetric Bianchi-I model filled with strange quark matter (SQM) is explored in f(R, Lm) gravity as a non-linear functional of the form f(R, Lm)=R/2 +L^α_m, where α is the free model parameter. We considered the special law of variation of Hubble’s parameter proposed by Berman (1983) and also used the power law relation between the scale factors to obtain the exact solution of the field equation, which matches the model of the universe. We also analyze the physical and geometrical aspects of the universe’s kinematic and dynamic behavior. Additionally, we employ equation-of-state (EoS) parameters and statefinder parameters as analytical tools to gain insights into the evolution of the universe. We use the ΛCDM model as a benchmark to validate the results. By placing the deviations of the universe from ΛCDM model and yet making important contributions to the study of the anisotropic nature of f(R, Lm) gravity within the framework of cosmological dynamics, the paper increases our comprehension of our cosmic evolution.

Cosmic Evolution in a Bianchi type-V Universe with Barrow Holographic Dark Energy with Granda-Oliveros Length Scale as IR Cutoff

Rajashree Mahanta — 2024-09-02

In this work, we construct a spatially homogeneous and anisotropic Bianchi type-V cosmological model with a hybrid expansion law by considering the universe to be filled with cold dark matter and non-interacting Barrow holographic dark energy with Granda-Oliveros length scale as IR cutoff. The physical and kinematical characteristics of the resulting model are discussed by studying the evolution of various parameters of cosmological importance such as the Hubble parameter, the deceleration parameter, the anisotropic parameter, the equation of state parameter, jerk parameter etc. We also examine whether the energy conditions are satisfied or violated. Our analysis reveals that the Null,Weak, and Dominant energy conditions are fullfilled, while the Strong Energy Condition is violated, which supports the accelerated expansion of the universe. Statefinder diagnostics have also been performed based on recent cosmological observations in order to compare our model with different dark energy cosmological scenario. Additionally, we establish the correspondence between the quintessence scalar field and the Barrow holographic dark energy model, supporting our description of the universe’s accelerated expansion.

Examining the Viscous Ricci Dark Energy Cosmological Model in General Theory of Gravitation

T. Chinnappalanaidu — 2024-09-02

This study focuses on dynamically exploring Marder-type spacetime containing viscous Ricci dark energy within the framework of general relativity theory. To find a solution of the field equations, we use the relation between metric potentials and the average scale factor a(t)=(sinhβ₁t)^1/β₂, this leads to a seamless transition of the Universe from its initial decelerating phase to the current accelerating phase. Here, we have obtained the cosmological parameters and ω_de-ω'_de plane for the derived model. Also, dynamical features of the derived cosmological model are analyzed through diagrams.

A Study of Time Evolution of Some Cosmological Parameters in The Framework of an Anisotropic Kaluza-Klein Metric Using an Empirical Exponential Scale Factor

Sudipto Roy — 2024-09-02

The present study attempts to determine the time dependence of some cosmological parameters in flat space (i.e., a space of zero spatial curvature), in the framework of an anisotropic Kaluza-Klein metric. The field equations for this work have been derived from the metric by assuming a power-law relation between the normal scale factor and the scale factor corresponding to the extra (i.e., the fifth) dimension. An empirical scale factor, having the expression of a = B exp(αt^β), has been used here in order to derive the expressions for some cosmological parameters as functions of time. The reason for choosing this scale factor is that it generates an expression for the deceleration parameter which undergoes a change of sign, as time goes on, from positive to negative, indicating a transition of the universe from an initial state of decelerated expansion to that of an accelerated expansion (which is its present state), as has been inferred from astrophysical observations. We have graphically depicted the evolution of some cosmological parameters with respect to what one may call the relative time, expressed as t/t₀, where t₀ is the present age of the universe. The present study finds the dynamical cosmological constant (Λ) to be negative, and it becomes less negative with time, changing at a gradually decreasing rate. The dependence of pressure of the all-pervading cosmic fluid upon density, corresponding to the fifth dimension, has been described in terms of a skewness parameter (δ) which comes out to be decreasing with time. The anisotropy factor has been calculated in this study, whose numerical value has been found to be decreasing with time, indicating a journey of the universe towards phases of gradually smaller anisotropy.

Pilgrim Dark Energy Bianchi Type-I f(T) Gravity Model

Siraj N. Khan — 2024-09-02

In this work, we have analyzed Bianchi type-I space-time (spatially homogeneous and anisotropic), using an interacting two fluid - dark matter (DM) and Pilgrim dark energy (PDE) in the framework of f(T) gravity by taking into consideration the infrared (IR) cut-off as a candidate of Hubble’s horizon L=1/H. We have also performed the state-finder diagnostics and in addition, energy conditions are discussed to verify accelerating expansion of the universe.

Study on Anisotropic Dark Energy Cosmological Models in Generalized Brans-Dicke Theory

M. Vijaya Santhi — 2024-09-02

In this present paper, we have investigated the dark energy cosmological model in Bianchi−V I0 spacetime by considering generalised Brans-Dicke theory, self-interacting potential, and a dynamical coupling parameter. For this purpose, we have utilised a hybrid scale factor to approximate the dynamical behaviour of the deceleration parameter. The deceleration parameter should display distinctive flipping behaviour at the transition redshift since the universe is thought to have changed from an early deceleration to a late temporal acceleration. We have studied six alternative transitioning dark energy models on the basis of observational restrictions on the transition redshift. For each model, the behaviour of the dynamical scalar
field, the Brans-Dicke parameter, and the self-interacting potential are examined. On top of that, we used the generalised Brans-Dicke theory to estimate how the Newtonian gravitational constant changes over time.

Spectral and Timing Study of V404 Cygni with CHANDRA Observations

S. Rita Devi — 2024-09-02

We present the spectral and timing study of V404 Cygni from all its available Chandra observations and which recently come up in public domain of Chandra data archive. The data reduction and analysis were done using CIAO 4.14 and HEASOFT 6.30.1. The spectral analysis was done using spectral fitting package XSPEC version 12.12.1, available in the Heasoft package. The spectra of the source is fitted in the energy range 0.3 -8.0 keV using two empirical spectral models - the absorbed power law and an absorbed disk-blackbody. The X-ray binary source V404 Cygni is found to be in the quiescent state having the X-ray luminosity in the range with
few times 1032 erg s⁻¹. The source is found to be in the hard state and is well explained by power-law model with a powerlaw photon index Γ ∼ 2 with n_H in the range ∼ (0.7 -1.2) × 1022 cm⁻². From timing analysis, Src-1 (V404 Cygni), in all the time bins- 0.5, 1 and 2 ks, the probability for the count rate to be constant is 0.17 ×10⁻³³ in all the observations in the year 2021 and 2023 (ObsID 23421, ObsID 23422, ObsID 23423 & ObsID 28927). However, in the year 2017 observation it is found to be less variable. This clearly shows the presence of short-term variability in kilo-seconds time-scales with the currently available Chandra data. So, it is indicative that the binary source V404 Cygni is more likely to be variable source both in long-term (years) as well as short-term (kiloseconds) scales.

On the Stability of Planetary Motions During Stellar Approaches

A.G. Mammadli — 2024-09-02

The problem of the spatial motion of a passively gravitating body during an to the central body of a perturbing body – a test star – is considered. Using the exact expression of the force function, an integral invariant relationship – a quasi-integral – was found. Due to the quasi-integral, the regions of possible motion of the passively gravitating body, the surfaces of minimal energy (a generalization of the zero velocity surfaces), and the singular points of these surfaces were determined. The stability of planetary motion according to Hill during the approach of a test star to the Solar System was investigated. Criteria for the possibility, as well as the impossibility of capturing the passively gravitating body by the test star, were established. According to the Hill stability criteria, critical values of the orbital parameters of the test star were established, at which the planets of the Solar System either become satellites of the test star or leave the bounds of the Solar System.

High-Order B-Spline Finite Difference Approach for Schrodinger Equation in Quantum Mechanics

Archana Senapati — 2024-09-02

This paper presents a new numerical method for solving the quantum mechanical complex-valued Schrodinger equation (CSE). The technique combines a second-order Crank-Nicolson scheme based on the finite element method (FEM) for temporal discretisation with nonic B-spline functions for spatial discretisation. This method is unconditionally stable with the help of Von-Neumann stability analysis. To verify our methodology, we examined an experiment utilising a range of error norms to compare experimental outcomes with analytical solutions. Our investigation verifies that the suggested approach works better than current methods, providing better accuracy and efficiency in quantum mechanical error analysis.

Impact of Ion Pressure Anisotropy in Collisional Quantum Magneto-Plasma with Heavy and Light Ions

Deepsikha Mahanta — 2024-09-02

We have examined collisional degenerate plasma composed of charged state of heavy positive ion and light positive as well as negative ion. Employing the reductive perturbation method, we derived the damped Korteweg-de Vries-Burgers (dKdV-B) equation and by using its standard solution we analyze the characteristics of the solitary-shock profile under varying parameters. Furthermore, with the application of planar dynamical systems bifurcation theory, the phase portraits have been analyzed. This dynamical system analysis allowed us to extract important information on the stability of these structures as represented by the dKdV-B equation.

Positively Charged Microparticle in Plasma with High-Energy Electron Beam

Aleksander A. Bizyukov — 2024-08-15

The processes of recharging, heating and evaporation of a positively charged microparticle (MP) introduced into the plasma with an injected high-energy electron beam are considered. It is assumed that the MP is charged outside the plasma and then introduced into the plasma by an accelerating field, where plasma and beam electrons hitting the MP heat and evaporate it. In addition to introducing the MP into the plasma, the positive MP charge provides an additional source of energy needed to heat and evaporate it. Using the OML theory, the system of current and energy balance equations was numerically solved and the conditions, under which the MP is heated to the boiling point of its substance, resulting in its intense evaporation, were determined. The influence of the energy of the electron beam on the process of MP recharging, as well as on the rate of its heating and evaporation, has been studied. An estimate of the particle entry velocity into the plasma has been made; the distances at which its recharging, heating to the boiling point and complete evaporation occur are determined. The work is carried out in order to creating plasma of a given elemental composition.

Method of Digital Processing of Optical Spectra of Magnetron Discharge Plasma

Inna Afanasieva — 2024-09-02

To solve the actual problems associated with the development of the theory of magnetron discharge and the expansion of its practical application, a digital method of recording and processing the discharge plasma luminescence spectra is proposed in this work. To obtain the discharge plasma glow spectra, a photographic technique was used, which allowed simultaneous recording of the entire radiation spectrum in the 390.0-700.0 nm region. An additional advantage of this technique is the ability to track spatial changes in the composition and properties of the plasma in the discharge in the selected direction. A Canon EOS 80D digital camera with remote control was used to record the optical signal. A graphical application OSA was created to process digital images of the discharge plasma luminescence spectra. The paper describes the functionality of this application: determination of the wavelength of a spectral line and its belonging to a certain chemical element; measurement of the spatial distribution of the intensity of a spectral line along the selected direction of radiation registration. Determining the wavelength of a spectral line in the application is possible in two modes of operation - automatic and manual. In the first mode, the algorithm developed in this paper determines the wavelength for all spectral lines whose intensity exceeds the background value at a height of 10 % of the lower spectral limit. The second mode allows you to independently select a single spectral line or several to determine their wavelengths. The first mode is used for quick analysis, while the second mode allows you to determine the length of the spectral line with greater accuracy. To interpret the spectral lines, the methodology of reference lines from the databases of spectral line tables for various elements is used. The possibility of both full automatic verification, where all elements are sequentially searched, and selective verification, where one or more elements are selected, is provided. The paper shows that the spatial distribution of the intensity of tungsten spectral lines, and thus of excited atoms in a magnetron discharge, is a complex function of the distance from the cathode, which depends on the discharge parameters. The proposed digital methodology makes it possible to significantly speed up the process of obtaining physical information and increase the accuracy in determining the spectrum parameters.

Numerical Simulation of the Dynamics of RF Capacitive Discharge in Carbon Dioxide

Valeriy Lisovskiy — 2024-09-02

In this research, the one-dimensional fluid code SIGLO-rf was used to study the internal parameters of RF capacitive discharge in carbon dioxide, focusing mainly on time-averaged and spatio-temporal distributions of discharge parameters. With the help of this code, in the range of distances between electrodes d = 0.04 – 8 cm, RF frequencies f = 3.89 – 67.8 MHz, and values of carbon dioxide pressure p = 0.1 – 9.9 Torr, averaged over the RF period axial profiles of the density of electrons, positive and negative ions were calculated as well as potential and electric field strength. It is shown that the discharge plasma in CO₂ contains electrons, positive ions, as well as negative ions. The negative ions of atomic oxygen are formed by the dissociative attachment of electrons to CO₂ molecules. Studies of the spatio-temporal dynamics of plasma parameters (electron density, potential and electric field strength, as well as ionization and attachment rates) in RF capacitive discharge in CO₂ showed that during half of the RF period, 1 to 3 ionization bursts are usually observed. They correspond to stochastic heating in the near-electrode sheath and the formation of passive and active double layers near the sheath boundaries. The passive double layer appears in the cathode phase and maintains the discharge plasma. The active layer is formed in the anodic phase and ensures a balance of positive and negative charges escaping to the electrode during the RF period. It was found that when the conditions pd = 2 Torr cm and fd = 27.12 MHz cm are met simultaneously, during half of the RF period, 4 intense ionization peaks are observed: resulting from stochastic heating, passive, active, and additional (auxiliary) double layers. The auxiliary double layer helps bring electrons to the surface of the temporary anode and occurs near its surface inside the near-electrode sheath. Using the similarity law, the conditions for the existence of these 4 ionization peaks in a wide range of RF frequencies, carbon dioxide pressures, and distances between electrodes were verified.

Numerical Study of Convective Flow of Casson Fluid Through an Infinite Vertical Plate with Induced Magnetic Field

Hiren Deka — 2024-09-02

The present objective is to numerically analyze the induced magnetic field (IMF) effect of an unsteady MHD flow of Casson fluid through two infinite vertical plates. The effect of radiative heat has been scrutinized. Governing non-dimensional PDEs of the flow are discretized by the finite difference method to some algebraic system of equations, which is then numerically solved concerning the boundary conditions. The effects of the radiations, magnetic Prandtl number, Prandtl number, Hartmann number, and Casson parameter on temperature profile, velocity profile, and induced magnetic field have been depicted through graphs. The radiative effect and Prandtl number have considerable influence on the surface drag force and also on the rate of heat transfer.

Effect of Rarefactions and Convective Heat Change on Free Convective Unsteady MHD Flow in a Slip-Flow Regime Past a Vertical Wall with Convective Surface Boundary Condition

Hemant Agarwal — 2024-09-02

The study investigates the unsteady free convective two-dimensional MHD flow past a vertical porous plate with convective surface boundary condition in porous medium in slip flow regime under the action of variable suction velocity. Analytical solutions are obtained for the system using perturbation technique that converts non-linear coupled governing partial differential equations into non-dimensional form of ordinary differential equations. Effects of variable suction velocity, rarefactions parameter and heat change parameter are analysed and discussed graphically for various values of effective physical parameter such as Grasshof number, Magnetic field parameter, Prandtl number, Permeability parameter on fluid velocity and temperature, skin friction, and heat transfer.

Entropy Generation Analysis on Hybrid Dusty Nanofluid Flow Over a Heated Stretching Sheet: Aerospace Technology

Gunisetty Ramasekhar — 2024-09-02

The past few years have seen enormous investments in research and development of next generation technologies with potential use in aerospace. Engine oil provides grease, air conditioning, maintenance, rust prevention, reduced sound and turbine functioning among its many functions within an airplane engine. Among these, lubrication is paramount. Without lubrication, it goes without saying that any moving components would wear out very fast. The present study investigates the significance of heat transport properties entropy generation on MHD dusty hybrid nanofluid flow over a heated stretching sheet in the presence of heat generation. By using the suitable self-similarity variables, the partial differential equation is transformed into ordinary differential equations. After then, the dimensionless equations are solved by using the MATLAB solver in bvp4c scheme. Graphs and tables are explained how the operational factors affect fluid flow efficiency. The velocity profile enhanced for increasing magnetic field values, however the energy outline exhibited the reverse behavior, which we observed. During the course of our research, we came to the conclusion that mixed nanofluids are superior to dusty small fluids in terms of their ability to transport energy transporters.

Exact Analysis of MHD Casson Fluid Flow Past an Exponentially Accelerated Vertical Plate in a Porous Medium with Radiation Absorption, Heat Generation, and Diffusion-Thermo Effects with Thermal and Solutal Ramped Conditions

Dibya Jyoti Saikia — 2024-09-02

The current investigation aims at to examine the effect of radiation absorption, heat generation and Dufour number on MHD Casson fluid flow past an exponentially accelerated vertical plate in a porous medium with chemical reaction. The governing equations for momentum, energy and concentration are solved by implementing the Laplace transformation method. Skin friction, rate of heat transfer and rate of mass transfer expressions are also extracted and depicted in tabular form. Investigation simulates that Casson parameter diminished the fluid velocity, whereas energy flux due to a mass concentration gradient improves the temperature field of the flow problem. In addition to this, temperature field is observed to be developed under the influence of radiation absorption and heat generation. Furthermore, the effects of different non-dimensional parameters on velocity field, temperature fluid and species concentration are exhibited graphically.

Flow of Magnetohydrodynamic Maxwell Fluid in Darcy – Forchheimer Model, With Cattaneo – Christov Heat Flux, Over A Stretching Sheet Subjected to Convective Boundary Conditions

D. Dastagiri Babu — 2024-09-02

This research communication explores the Darcy - Forchheimer flow of a chemically reacting non-Newtonian Maxwell fluid over a stretching sheet, incorporating the Cattaneo – Christov heat flux under a convective boundary condition. The fluid flow is described by a set of partial differential equations, which are subsequently transformed into a system of nonlinear ordinary differential equations. To solve these equations numerically, the BVP4C Method was employed after appropriately defining non dimensional variables and implementing similarity transformations. The impacts of diverse active parameters such as Deborah parameter, Darcy‑Forchheimer parameter, magnetic parameter, Biot number, and porous parameter are examined on the velocity, temperature, and concentration profiles. In addition, the value of the Skin friction, Nusselt number is calculated and presented through tabular forms.

MHD Stefan Flow of Casson Nanofluid Complete a Porous Medium in The Presence of Chemical Reaction with The Effect of Thompson as Well as Troian Slip Over a Plate in the Company of Radiation

Anitha Deevi Reddy — 2024-09-02

In this work, we report the effects of Thompson, Troian slip, and Stefan blowing on the magnetohydrodynamic (MHD) Cassonnanofluid behavior via a porous media while a chemical reaction is taking place. We also examine the effects of radiation parameters, Joel heat, and velocity distribution using a two-phase model for nanofluids. Similarity transformations may be used to convert the primary Partial Differential Equations (PDEs) into Ordinary Differential Equations (ODEs). MATLAB Shooting and Runge-Kutta algorithms may be used to solve nonlinear equations. The variations in non-dimensional parameters show the effects on mass transfer, heat, and fluid flow properties. It is shown that the skin friction coefficient falls as the Stefan blowing parameter S increases. As the values of the Thompson and Troian slip parameters increase, the fluid concentration decreases. With an increase in Nt, Nb, and k, the fluid's heat rises but its concentration falls. The results of this analysis provide several enticing aspects that are going to give merits for further study of the problems.

Influence of Heat and Mass Transmission on the MHD Fluid Circulation in Conjunction with an Upright Surface in the Emergence of Radiation Thermophoresis and the Dufour Repercussions

Ashik Hussain Mirza — 2024-09-02

The current research simulates the mass and heat energy transmission model on MHD fluid flow under concentration and temperature deviations on a two-dimensional viscous fluid along an upright facet. Following boundary layer estimations, mathematical simulations for the movement of fluids, the conveyance of heat and mass exposed to radiation, thermophoresis, and Dufour consequences are generated as a set of partial differential equations. The surface's resilient suction was assessed. The built-in solver bvp4c in MATLAB is used for numerically debugging the aforementioned models. Through the inclusion of visualizations and tables, the detrimental effects of influencing variables are examined on the velocity, temperature as well as concentration gradients in conjunction with on the skin friction, Nusselt number, and Sherwood number. Excellent coherence may be shown when comparing between the most present findings and those that have previously been made available in the literature in specific limited circumstances. The Dufour effect, radiation, thermophoresis, and the Grashof number are all factors that influence fluid motion and heat transmission at the interface layer of dirt. Moreover, developments in the Shearing stress, Nusselt number, and Sherwood number coefficient are calculated. The findings are crucial for optimizing a variety of fluid-based technologies and systems, allowing developments in a number of industries including energy-effectiveness, electronics cooling, pursued medicine administration, and many more.

Effects of Thermal and Mass Stratification on Unsteady MHD Flow Past an Oscillating Vertical Plate Embedded in a Porous Medium with Variable Surface Conditions

Pappu Das — 2024-09-02

oscillating vertically in its own axis in which it is embedded in a porous medium with variable heat and mass diffusion. For concentration, temperature and velocity fields, the non-dimensional governing equations are solved using the Laplace transform method for the unitary Prandtl and Schmidt numbers, when the plate is oscillating in its own plane harmonically. Numerical computations are carried out and presented in graphs for different physical parameters like thermal Grashof number, phase angle, mass Grashof number, stratification
parameter and time on concentration, velocity, temperature, plate heat flux, mass flux and skin friction. The findings of this study can be utilized to enhance comprehension of MHD flow on vertical oscillating plate in combined stratified environments. Significant findings arising from the mass and thermal stratification are compared to the scenario in which stratification is absent.

Modeling Temperature Dependence of The Combined Density of States in Heterostructures with Quantum Wells Under the Influence of a Quantizing Magnetic Field

Ulugbek I. Erkaboev — 2024-09-02

In this work, the dependence of the oscillation of the combined density of states on a strong magnetic field in heterostructures based on a rectangular quantum well is studied. The effect of a quantizing magnetic field on the temperature dependence of the combined density of states in nanoscale straight-band heterostructures is investigated. A new mathematical model has been developed for calculating the temperature dependence of the two-dimensional combined density of quantum well states in quantizing magnetic fields. The proposed model explains the experimental results in nanoscale straight-band semiconductors with a parabolic dispersion law.

Study of Optical, Electrophotographic and Holographic Parameters of As-Se Condensates from the Prehistory of the Original Bulk Materials

Sharifa B. Utamuradova — 2024-09-02

The results of a study of the optical, electrophotographic and holographic parameters of As-Se condensates from the prehistory of the original bulk materials are presented. It has been established that the electrophotographic parameters of freshly deposited As₄₀Se₆₀ layers change significantly with temperature; the dependences of the maximum charging potential (U₀) and the half-decay time of the potential (τ_1/2) of electrophotographic As₄₀Se₆₀ layers in the dark on the processing temperature of the melt of the starting material are shown. The dependence of the half-life of the potential in the dark, as well as the properties of bulk samples, has an extremum in the region of T_sub~500°C. The correlation between the dependences of the properties of bulk samples and the electrophotographic parameters of the layers on T_sub indicates that the structural features of the source material in the deposition mode used affect the structure of the films.

Structural Properties of Al-Doped ZnO Films

Sirajidin S. Zainabidinov — 2024-09-02

In this study, the results of the investigation of the influence of Al atoms on the structural characteristics of ZnO films obtained by the sol-gel method are presented. It has been determined that the glass substrates consist of subcrystallites with dimensions of 28.6 nm, having cubic unit cells with lattice parameters a = 0.3336 nm, and their surfaces belong to the crystallographic orientation (111). It has been identified that the grown thin ZnO films consist of subcrystallites with dimensions of 39.5 nm, having a wurtzite structure with lattice parameters a = b = 0.3265 nm and c = 0.5212 nm, respectively. It has been determined that at the boundaries of the division of these subcrystallites, polycrystalline regions with sizes of 12.6 nm, 28.3 nm, 30 nm, and 33 nm are formed. Additionally, nanocrystallites with sizes of 56.8 nm self-assemble on the surface areas of the deposited films. The increase in the values of the “c”axis of the hexagonal crystal lattice of ZnO films by 0.0009 nm when doping Al atoms from 1% to 5% is explained by the shift of the main structural line (002) at small angles (Δθ=0.12°). It has been established that nanocrystallites with lattice parameters аn = 0.5791 nm, belonging to the spatial group Fd3m, self-assemble on the surface areas of ZnO:Al films. the curve due to the presence of a monoenergetic level of fast surface states at the heterojunction.

The Mechanism of Current Transfer in n-GaAs – p(ZnSe)1-x-y(Ge2)x(GaAs1–δBiδ)y Heterostructures

Sirajidin S. Zainabidinov — 2024-09-02

The I-V characteristics of heterostructures n-GaAs – p-(ZnSe)_1–x–y(Ge₂)_x(GaAs_1–δBi_δ) exhibit a characteristic quadratic law - J~V² I-V curve, followed by a sharp pre-breakdown current growth, which well explains the observed straight branch of the I-V characteristics and this regularity remains unchanged at different temperatures. The analysis of the I-V characteristics of n‑GaAs‑p‑(ZnSe)_1‑x‑y(Ge₂)_x(GaAs_1–δBi_δ) heterostructures with an extended intermediate solid solution layer shows that the drift mechanism of charge transport predominates under forward bias conditions.

An Optimized Ultrasonic Spray Pyrolysis Device for The Production of Metal Oxide Films and Their Morfology

Sirajidin S. Zainabidinov — 2024-09-02

In this work, we developed an optimized ultrasonic spray pyrolysis device for obtaining metal oxide films. The key benefit of this facility lies in its cost-effectiveness and its ability to consistently coat extensive surfaces without sacrificing the integrity of the semi-conductive films, thus streamlining the manufacturing process of semiconductor films. The resulting films exhibit the following attributes: the thickness of the deposited layer is approximately 400 nm, while the diameters of ZnO_1-xS_x nanocrystals range from 50 to 200 nm, oriented perpendicular to the crystallographic orientation (111). In the production of nanorods, the average height is estimated to be approximately 30-50 nm, with a density of 2.9×10¹¹ cm⁻² being indicated.

Photoelectric Characteristics of the Heterojunction n-GaAs-p-(GaAs)1-x-y(Ge2)x(ZnSe)y

Akramjon Y. Boboev — 2024-09-02

The photoelectric properties of n-GaAs – p-(GaAs)_1–x–y(Ge₂)_x(ZnSe)_y heterostructures have been investigated both in photodiode and photovoltaic modes. It has been revealed that the spectral dependence of the photocurrent covers a wide range of energy intervals, ranging from 1.07 eV to 3 eV. It has been demonstrated that as the temperature of the crystallization onset (T_oc) increases, the peaks of the spectral dependencies of the photoelectromotive force (photo-EMF) shift towards shorter wavelengths. It has been observed that as the crystallization onset temperature (T_oc) of the solid solution layer (GaAs)_1–x–y(Ge₂)_x(ZnSe)_y increases, the lifetime of photo carriers increases from 10^-7 s at T_oc=650°C to 5·10^-5 s at T_oc=730°C. It is demonstrated that the peaks of the intrinsic photoluminescence band shift towards shorter wavelengths with an increase in the temperature of the crystallization onset. Additionally, the study of the intrinsic spectral region of photoluminescence in samples across the thickness of the epitaxial layer confirms the variability of the obtained structures.

Influence of Mixing Valence Band States to the Conduction Band States on Two-Quantum Linear-Circular Dicroism in Semiconductors

Rustam Y. Rasulov — 2024-09-02

A quantitative theory of two-photon linear-circular dichroism caused between the subbands of light and heavy holes of the valence band and conduction band is constructed, which takes into account the admixture of valence band states to the conduction band states and the temperature dependence of the band gap (E_g(T)) in semiconductors of tetrahedral symmetry in the multiband Kane model. It is shown that the type of oscillatory angular dependence or the amplitude values of the probabilities of two-photon optical transitions depend on the state of light polarization. This is due to the fact that, under the influence of linearly polarized light, alignment along the pulse occurs, and under the action of circularly polarized light, the moments of current carriers are oriented. It has been determined that the probability of two-photon optical transitions from the heavy hole subband to the conduction band of semiconductors at a fixed temperature increases with increasing frequency, passes through a maximum, and sharply decreases regardless of the degree of polarization of light, as well as the band gap.

Theory of Electron Transport in Two-Barrier Five-Layer Semiconductor Structures

Rustam Y. Rasulov — 2024-09-02

The dependence of the transparency coefficient of a five-layer two-barrier structure on the electron energy and the ratio of the widths of two neighboring potential barriers is calculated. It is shown that the extremum of the transparency coefficient significantly depends on the geometric dimensions of the structure layers. In a symmetric five-layer two-barrier semiconductor structure, the condition for the occurrence of "resonant" electron transitions is defined. It is demonstrated that the mechanism of such (resonant) transitions is explained by the interference of de Broglie waves of electrons in the potential well, where the phases of de Broglie waves are determined by the geometric dimensions of the structure, and their amplitudes - by the ratio of the carrier energy to the height of the potential barrier. It has been established that with an increase in the effective mass of charge carriers, the number of intersections of the quantities f_R (ξ) and ((1-2ξ))/(√(ξ-ξ²) increases. These intersections determine the dimensionally-quantized levels where electrons are localized.

Theory of Linear-Circular Dichroism in Monoatomic Layers of Transition Metal Dichalcogenides Taking into Account the Rabi Effect

Rustam Y. Rasulov — 2024-09-02

We have developed a theory of dimensional quantization for nanostructures, both one-dimensional and zero-dimensional, constructed from monoatomic layers of transition metal dichalcogenides (TMDCs). This theory has enabled us to derive expressions for the energy spectra of charge carriers in both even and odd states (relative to coordinate inversion), as these states occur within quantum-confined lines and points of the TMDC monoatomic layers, dependent on their geometric dimensions. Our numerical analysis provides a detailed exploration of the quantum-confined energy states of electrons within these nanostructures, offering insights into their potential applications in advanced nanoelectronic devices. This work not only advances our understanding of the energy characteristics of TMDC monoatomic layers but also contributes to the broader field of material science by exploring the effects of dimensional quantization on electronic properties.

Charge Transport Mechanism in Implanted p-GaSe:H+ Single Crystal

R.S. Madatov — 2024-09-02

The study analysed the impact of radiation defects on p-GaSe single crystal implanted with H⁺ ions (70 keV) on its charge transport mechanism. The research was conducted at 100 K and 300 K in an electric field of 10²-10⁴ V/cm. The study found that the activation energy of charge carriers injected at low temperatures and electric fields E < 10³ V/cm ranged from 0.23-0.39 eV. This was observed due to the trapping of charge carriers in concentration traps of approximately 9·10¹³ cm^-3, leading to monopolar injection. In the fields, E > 10³ V/cm, a sharp increase in current was observed, which was explained by the thermal ionisation of local levels following the Frenkel mechanism. The study determined that the charge transport mechanism in GaSe:H+ crystals at low temperatures has a non-activated character.

Analysis of the Influence of Formation of Pd Silicides on Surface Layers of Si on the Diffusion of Atoms of Contacting Metal

D.А. Tashmukhamedova — 2024-09-02

4-probe measurements of surface resistivity, measurements of dark and light current-voltage characteristics, the possibilities of using a thin PdSi film to obtain perfect nano-sized ohmic contacts on the Si(111) surface have been investigated using Auger electron spectroscopy methods in combination with ion etching of the surface. It has been shown that the depth of Ni diffusion in the Ni-Si (111) system is 400 ‑ 500 Å at indoor temperature, and 70 – 80 Å in the Ni-PdSi-Si (111) system. The quality of the ohmic contact in the latter case does not change up to T = 800 K and withstands luminous flux illumination up to F = 1100 lux. It is shown that the resistivity of the PdSi film passes through a minimum at T = 900 – 1000 K. An analysis of the results obtained will be given in the article.

Anticipating Pressure Changes in Halides under Compression

Abhay Prakash Srivastava — 2024-09-02

A new equation of state (NEOS) for Halides has been developed using the theory of lattice potential and the concept of volume dependence of the short-range force constant. The derivation of this equation of state involved the use of the third-order approximation of the lattice potential. A comparative analysis was conducted between the isothermal equations of state, including Vinet EOS, Murnaghan EOS, Holzapfel EOS, Born-Mie EOS, Birch-Murnaghan EOS, and the newly derived NEOS. The NEOS was used to analyze the compression behavior of Halides, and it was found that Vinet EOS and NEOS agreed with the experimental data for Halides up to high compression. However, Murnaghan EOS, Born-Mie EOS, Holzapfel EOS, and Birch-Murnaghan EOS are usually less sensitive to calculating pressure at high compression. It was also observed that for some Halides, such as NaBr and NaI, Vinet EOS could not produce results consistent with experimental findings. In contrast, NEOS consistently produced results that matched the experimental findings for all Halides samples, unequivocally demonstrating its reliability and accuracy.

Study of Photoconductivity of Thin Films of Cadmium and Selenium Obtained by Chemical Deposition

L.N. Ibrahimova — 2024-09-02

In this work, the photoconductivity (PC) spectrum of thin CdSe films was studied. In the course of studies on glass substrates, thin films of cadmium and selenium with a thickness of h = 200 nm and h = 400 nm were selected. The thickness of the samples obtained by chemical deposition was determined by the gravimetric method. Since CdSe crystal is a light-sensitive semiconductor material, the photoconductivity of thin films has been studied. The spectra obtained during studies carried out at a wavelength λ = 600-1100 nm were analyzed. It has been established that the spectrum is chaotic, since in the h = 200 nm layers the phase is not completely formed. In the layers h = 400 nm, a maximum centered at the wavelength λ = 710 nm was recorded.

Optimization of The Influence of Temperature on The Electrical Distribution of Structures with Radial p-n Junction Structures

Jo`shqin Sh. Abdullayev — 2024-09-02

In recent years, advances in optoelectronics and electronics have prioritized optimizing semiconductor device performance and reducing power consumption by modeling new semiconductor device geometries. One such innovative structure is the radial p-n junction structure. In this work, we present a concept that submicron three-dimensional simulations were conducted on radial p-n junction structures based on GaAs material to investigate the influence of temperature ranging from 250K to 500K with a step of 50K on the electrophysical distribution, such as space charge, electro-potential, and electric field, in radial p-n junction structures, as well as various forward voltages. In particular, we focus on the shell radius within the structure: 0.5 μm and 1 μm for the shell. The modeling results were compared with the results obtained from solving the theoretical Poisson equation in the cylindrical coordinate system.

Preparation of Calcium Titanate Perovskite Compound, Optical and Structural Properties

Khujamkul T. Davranov — 2024-09-02

In this work, we have successfully fabricated a calcium titanate perovskite compound. The resulting CaTiO₃ compound was studied by preparing samples by compacting it in a powder state and using a Pousson device. The distance between the planes d_hkl, Miller indices (hkl), degree of crystallinity and amorphism, structure and lattice parameters of the calcium titanate perovskite compound were determined using an X-ray diffractometer. Also, according to the results of FT-IR analysis, the formation of CaTiO₃ perovskite is confirmed as a result of the study of molecular vibrations. The main broad peaks are observed in the range of 680÷400 cm^-1, the absorption band at the wave number of 543,93 cm^-1 corresponds to the specific stretching vibrations of Ti-O bonds and indicates the formation of the CaTiO₃ perovskite type structure implies. Based on the results of these measurements, it will be possible to use semiconductor compounds in the future to create nanofilms by magnetron sputtering.

The Low-Temperature Growth of Carbon Nanotubes Using Nickel Catalyst

Ilyos J. Abdisaidov — 2024-09-02

This study presents the results of a comprehensive investigation into the fabrication of single-walled carbon nanotubes (SWCNTs) employing chemical vapor deposition (CVD) technique, with nickel nanoparticles serving as crucial catalysts. These nanoparticles are synthesized via the reduction of oxide precursors using hydrogen and are strategically incorporated with ethanol vapor as the primary carbon source. The effectiveness and reproducibility of this synthesis method are thoroughly validated using advanced analytical techniques. Particularly noteworthy is the demonstrated ability to conduct the process at relatively low temperatures, not exceeding 500°C, which is of significant importance. Such precise control over synthesis conditions not only augurs well for the scalability of SWCNT production but also carries substantial implications for the advancement of nanomaterial synthesis methodologies.

Effect of Heating of Charge Carriers and Phonons on The Contact Resistance of Rectifying Metal-Semiconductor Structures

Gafur Gulyamov — 2024-08-06

The dependence of the temperature of charge carriers and phonons on the contact resistance of the Schottky diode is calculated. It is shown that the increase in contact resistance depends on the current passing through the diode, the surface and volume heat transfer coefficients of electrons and phonons, barrier height, the dimensions of the diode, as well as scattering mechanisms, relaxation time of energy and momentum.

Study of Structural and Vibrational Properties of Cu2In4Se7 by Analytical Methods

S.I. Ibrahimova — 2024-09-02

The compound Cu₂In₄Se₇ was synthesized, the crystal structure and atomic dynamics were studied. The studies were carried out at room temperature and under normal conditions using XRD, Raman spectroscopy and FTIR spectroscopy. The obtained X-ray structural spectra were analyzed by the Rietveld method and various crystallographic parameters were determined. It was established that the crystal structure of this compound corresponds to tetragonal symmetry with the space group P-42c (112). As a result of the analysis of the Raman spectrum with the Gaussian function, it was established that in the Cu₂In₄Se₇ crystal in the frequency range ν = 0–800 cm^-1 3 main vibrational modes are observed: ν₁ = 146 cm^-1, ν₂ = 171 cm^-1 and ν₃ = 229 cm^-1. It was found that these modes correspond to vibrations of InSe4 tetrahedra formed by In-Se bonds. As a result of analysis of the FTIR spectrum, it was established that 3 main vibration modes are observed in the Cu₂In₄Se₇ crystal in the wavenumbers range ν = 400-4000 cm^-1. These modes are associated with water and carbon dioxide molecules in the sample.

Computational Investigation on the Structural, Electronic and Magnetic Properties of Si-Doped L10 FeNi Alloy for Clean Energy

Zineb Zine — 2024-09-02

For the first time, this study conducts a computational analysis by employing density functional theory (DFT) to investigate the effects of silicon doping as substitutional defects on the structural, electronic, and magnetic characteristics of the L₁₀-FeNi alloy. The aim of this study was to explore the potential applications of Si-doped FeNi compounds as alternatives to rare-earth permanent magnets. For this, we have performed full potential calculations of L₁₀-FeNi with substitutional Si-doping within a generalized gradient approximation. Two types of substitutional Si-doping (O_Ni/O_Fe) in the Ni/Fe site of the parent alloy have been investigated. The computed formation energy (E_f) indicates that the incorporation of silicon defects increases the structural stability of tetragonally distorted L₁₀-FeNi. Moreover, our findings demonstrate that the FeNi:Si(O_Ni) in the L₁₀-structure has a stable saturation magnetization (M_s), whereas the FeNi:Si (O_Fe) has a small reduction in M_s. Therefore, Si-substituted FeNi alloys can be tuned to become a good candidate for permanents magnets.

Investigation of Sensitive Thermal Sensors Based on Si and Si

Sharifa B. Utamuradova — 2024-09-02

In this work, new sensitive thermal sensors based on Si<Pt> and Si<Pd> were developed. Single-crystal n- and p-type silicon samples doped with phosphorus and boron during growth were used for the study. These samples were first doped with platinum and palladium, then subjected to ohmic contact with nickel. To manufacture temperature sensors based on n-Si˂Pd˃ and obtain an ohmic contact, this material was subjected to appropriate mechanical and chemical treatments. Metallic nickel with a thickness d = 1 μm was chemically deposited on its surface, followed by thermal annealing in a vacuum at T = 400-450℃ for t = 10 - 15 minutes. To compare the created temperature sensors, a special measuring device, a thermostat, was developed to ensure uniform heat transfer.

Development of a Capacitive Pressure Sensor Based on Nanoporous Anodic Aluminium Oxide

Trishna Moni Das — 2024-09-02

Capacitive pressure sensors make pressure sensing technology more accessible to a wider range of applications and industries, including consumer electronics, automotive, healthcare etc. However, developing a capacitive pressure sensor with brilliant performance using a lowcost technique remains a difficulty. In this work, the development of a capacitive pressure sensor based on nanoporous AAO fabricated by a two-step anodization approach which offers a promising solution for precise pressure measurement is fabricated by a two-step anodization approach. A parallel plate capacitive sensor was fabricated by placing two AAO deposited sheets are placed face to face, with the non-anodized aluminum component at the base functioning as the top and bottom electrodes. A variation in the capacitance value of the as fabricated sensor was observed over an applied pressure range (100 Pa-100 kPa). This change in capacitance can be attributed to the decrease in the distance between the two plates and the non-homogenous distribution of contact stress and strain due to the presence of nanoporous AAO structure. In this pressure range the sensor showed high sensitivity, short response time and excellent repeatability which indicates a promising future of the fabricated sensor in consumer electronics, intelligent robotics etc.

Silicon p-i-n Mesa-Photodiode Technology

Mykola S. Kukurudziak — 2024-09-02

The paper proposes the technology of silicon p-i-n mesa-photodiodes, which allows to exclude one high-temperature operation from the technological route. Reducing the number of thermal operations reduces the degree of degradation of the electro-physical characteristics of silicon during heat treatment, which also contributes to reducing the density of surface states at the SiSiO₂ interface. It is proposed to etch the mesa-profile by the method of chemical-dynamic polishing using a gold masking coating. The obtained photodiodes are cheaper than serial samples made by diffusion-planar technology and have higher sensitivity.

Numerical Simulation Study of The Increase in Electrical Efficiency of the CIGS-Based Solar Cell by SCAPS-1D

K. Madoui — 2024-09-02

Solar cells are currently the focus of a great deal of research. The aim is to reduce their cost price. To achieve this, we need to reduce the mass of the materials and increase the conversion efficiency of these solar cells. This has motivated research into the use of thin films such as a-Si, CdTe, CIGS. This increase in efficiency requires optimizing the performance of the photovoltaic parameters. In this modeling and simulation work, we use the SCAPS-1D software to study the effect of the recombination speed of the electrons and holes in the CIGS layer, the effect of the thickness of the layers and the effect of the gap energy of each layer of the material used for this solar cell on the short-circuit current Jsc, the open-circuit voltage Voc, the form factor FF and the electrical efficiency η of the CIGS cell for a Mo/p-CIGS/p-Si/In₂S₃/i-ZnO/Al-ZnO single-junction structure. In this study, we found that recombination speed affects the efficiency of the photovoltaic cell. The gap energy of the absorber layers influences the cell's efficiency, while the other layers (In₂S₃, ZnO, Al-ZnO) do not have a great influence on solar cell performance and increasing the thickness of the absorber layer has a major influence on efficiency, increasing it up to a certain limit. The thicknesses of the CIGS, p-Si, In₂S₃, i-ZnO and Al‑ZnO layers need to be in the order of 0.3µm, 0.8µm, 0.05µm, 0.07µm and 0.1µm respectively to achieve better efficiency (31.42%).

Performance Enhancement via Numerical Modeling and Optimization of FASnI3 Perovskite Solar Cell

Lahcene Kanouni — 2024-09-02

Perovskite-based solar cells are currently attracting growing interest from researchers and industry alike, thanks to the advantages of this type of solar cell, particularly in terms of manufacturing simplicity and the promising power conversion efficiency, which has recently reached remarkable levels. This paper focuses on numerical simulation to improve the performance of the Formamidinium Tin Iodide (FASnI₃) solar cell configuration by using Cerium Dioxide (CeO₂) as ETL and Poly (Triaryl Amine) (PTAA) as HTL. The simulation has been carried out using Solar Cell Capacitance Simulator (SCAPS-1D) tool under the spectrum of AM 1.5 G. An intensive modeling has been realized to improve the output parameters of the suggested configuration based on FASnI₃as absorber. The proposed structure (ITO/CeO₂/FaSnI₃/PTAA/Au) achieves a tremendous power conversion efficiency (PCE) of 39.24%, an open-circuit voltage (V_OC) of 1.31 V, a short-circuit current density (J_SC) of 33.7 mA/cm² and a fill factor (FF) of 90.12%.

Strengthen the Power Conversion Efficiency of Solar Cell Based RbGeI3: Numerical Approach

Lazhar Loumachi — 2024-09-02

The current study employs numerical simulations via the SCAPS-1D platform to investigate the performance of solar cells based on perovskite, with RbGeI₃ utilized as an absorber material possessing a wide bandgap of 1.31 eV. Through systematic exploration of various parameters including temperature, layer thickness, doping, and defects, the study aims to enhance the efficiency of the solar cells, considering their sensitivity to temperature variations. Results demonstrate that the proposed configuration effectively extends the absorption spectrum into the near-infrared region, with the thickness of the RbGeI₃ layer emerging as a critical factor influencing device performance. Analysis reveals that the series resistance peaks at 2 Ω·см², while the shunt resistance achieves optimal output parameters of up to 10³ Ω·см². Moreover, optimization efforts yield a solar cell exhibiting a power conversion efficiency of 24.62%, fill factor of 82.8%, open circuit voltage of 0.99V, and short circuit current density of 33.20 mA/cm² at a RbGeI₃ thickness of 0.6 um. This comprehensive numerical investigation not only enhances understanding of the intricate factors influencing perovskite solar cells but also suggests promising avenues for future advancements in the field.

Enhancing ZnO/Si Heterojunction Solar Cells: A Combined Experimental And Simulation Approach

Fakhriddin T. Yusupov — 2024-09-02

In this study, we explore the fabrication and optimization of ZnO/Si heterojunction solar cells to enhance their performance through precise control of electron affinity and bandgap properties. ZnO thin films were synthesized using thermal oxidation in a high-vacuum chamber, followed by annealing to improve crystallinity and electrical characteristics. The photovoltaic performance of the ZnO/Si heterojunction solar cells was systematically characterized, and Quantum ESPRESSO simulations were employed to refine the electronic properties of ZnO. Our results show significant improvements in open-circuit voltage, short-circuit current density, and overall conversion efficiency. The optimization of ZnO/Si heterojunction solar cells involves enhancing the electronic properties of ZnO thin films. Quantum ESPRESSO simulations were utilized to optimize the ZnO structure, calculate the band structure and density of states (DOS), and study the effects of Ga and Mg doping on the electronic properties of ZnO. The initial step in our study involved the structural optimization of ZnO to determine its lowest energy configuration. The optimization of the band offset engineering to improve the efficiency of n-ZnO/p-Si photovoltaic cells was found to be critical. Doping ZnO with Ga and Mg improved the band alignment with Si, reduced recombination losses, and enhanced charge carrier mobility. Our findings underscore the potential of optimized ZnO/Si heterojunction solar cells for high-efficiency solar energy conversion, demonstrating their viability as cost-effective and efficient solutions for renewable energy applications. This study highlights the importance of precise material engineering and simulation-driven optimization in developing advanced photovoltaic devices.

Impact of Temperature, Irradiation Duration on Performance of Organic/Ru-Dye/Inorganic Solar Cells

Hmoud Al-Dmour — 2024-09-02

This study investigates the impact of ambient conditions on the performance of P3HT/Ru-dye/nc-TiO₂solar cells (TLSCs). It has been found that the increase of temperature and irradiation duration affect on the parameters of TLSCs. When the temperature was increased from 293 k to 393 k , the short circuit current density (J_sc) and open circuit voltgae (V_oc) decrease from 2.2 to 1.7 mA/cm² and 0.7 V to 0.5 V respectively. That is attributed to the effect of high temperature on recombination of photo-generated charges and reduction of shunt resistance (R_sh ) in the TLSC. Moreover, we also present the effect of irradiation duration on performance of the TLSCs. The measurement reveals that J_scdecreased by 0.5 mA/cm² while V_oc decreased by ~ 0.18 V during 4800 s illumination. This decrease suggests the filling of traps or defects at the interface with photo-genertated charges. Finally, the maximum output power of TLSCs dropped by almost half within 6 days during a 20-day test because of affecting atmosphere moisture on the interface properties between dye/ nc-TiO₂ and P3HT.

Design and Performance Analysis Of Complete Solid-State Dye Sensitised Solar Cell Using Eosin-Y Xanthene Dye: a SCAPS -1D Simulation Study

K.R. Dhandapani — 2024-09-02

This paper reports the theoretical simulation study of the performance of a complete solid-state dye-sensitised solar cell with Eosin-Y as the photosensitizer and PEDOT: PSS as the hole transport layer. SCAPS-1D software is used for the simulation under quasi-ideal conditions and got an optimised efficiency of 4.19%, which matches much with the reported experimental values in the literature. These finding indicates the potential of Eosin-Y as a cost-effective photosensitiser capable of performing even under dim light conditions.

SCAPS-1D Analysis of Non-Toxic Lead-Free MASnI3 Perovskite-Based Solar Cell Using Inorganic Charge Transport Layers

Matthew I. Amanyi — 2024-09-02

Perovskite solar cells (PSCs) have gained a lot of attention due to their high efficiency and low cost. In this research paper, a methylammonium tin iodide (CH₃NH₃SnI₃) based solar cell was simulated using a one-dimensional solar cell capacitance simulation (SCAPS-1D) tool. The SCAPS-1D tool is based on Poisson and the semiconductor equations. After thorough investigation, the initial device presents the following parameters; power conversion efficiency (PCE)=15.315%, fill factor (FF)=64.580%, current density (J_sc)=29.152 mA/cm^2, and open circuit voltage (V_oc)=0.813 V. The effect of absorber and ETL thicknesses were explored systematically. The performance of the simulated device was significantly influenced by the thickness of the absorber and ETL. The optimized absorber thickness was 0.5 µm and the ETL thickness was 0.02 µm, giving rise to an optimized PCE of 15.411%, FF of 63.525%, J_sc of 29.812 mA/cm², and V_oc of 0.814 V. Additionally, the effect of temperature on the optimized device was evaluated and found that it affects the performance of the device. This model shows the prospect of CH₃NH₃SnI₃ as a perovskite material to produce toxic-free environment-friendly solar cells with high efficiency.

Performance Optimization of MgHfS3 Chalcogenide Perovskite Solar Cells Using SCAPS-1D

Adeyinka D. Adewoyin — 2024-08-20

In this work, magnesium hafnium sulfide MgHfS₃ perovskite solar cells have been investigated using numerical modelling and simulation. Perovskite solar cells have received increasing recognition owing to their promising light-harvesting properties. The modelling and simulation of MgHfS₃ was successfully carried out using the Solar cell capacitance simulator (SCAPS-1D) software. Consequently, this study developed a base model structure of FTO/TiO₂/MgHfS₃/Cu₂O/Au and subsequently explored the effect of varying device layer properties such as absorber thickness, total and interface defect densities with a view of optimizing these parameters for better device performance. Simulating the base model gave the performance characteristics of 0.99 V, 25.21 mA/cm², 57.59%, and 14.36% which are the open-circuit voltage (V_oc), short-circuit current density (J_sc), fill factor (FF) and PCE respectively. The optimal absorber thickness was found to be 300 nm and the optimum density of defects for both TiO₂/Absorber interface and Absorber/Cu₂O interface are respectively 10¹⁰ cm^-3 and 10⁹ cm^-3. The obtained optimized PV parameters are V_oc = 1.2629 V, J_sc = 24.44 mA/cm², FF = 89.46% and PCE = 27.61%. Also, it was established that increasing the device temperature beyond 300K enhanced the short circuit current while other performance characteristics gradually declined. The obtained results suggest that chalcogenide MgHfS₃is a potential absorber material candidate for the production of cheap and very efficient environment-friendly perovskite solar cells.

Radiation of Electromagnetic Waves by Regular and Biconical Dipoles with Variable Distributed Surface Impedance and Arbitrary Excitation

Mikhail V. Nesterenko — 2024-09-02

An approximate analytical solution of a problem concerning the radiation of electromagnetic waves by regular and biconical dipoles with constant and variable complex distributed surface impedance and arbitrary excitation is derived. Solution correctness is confirm by satisfactory agreement of experimental and numerical results from well-known literary sources. Numerical results are given for the input characteristics and radiation fields of the dipoles in the cases of its symmetric and asymmetric excitation by a point source.

Influence of Phthalic Acid on the Process of Dendrite Development in Low-Density Polyethylene During Electrical Breakdown

Sh.A. Zeynalov — 2024-09-02

The presented work presents the results of a study on the effect of small amounts of phthalic acid additives on dendrite formation in low-density polyethene (LDPE). Based on the results obtained, it is shown that the dendrite resistance of LDPE, as expected, increases with the introduction of 0.05 wt% phthalic acid. The established increase in dendrite resistance of LDPE with the introduction of phthalic acid can primarily be explained based on a decrease in inhomogeneities in the form of air pores as a result of accelerated structure formation and the emergence of a more homogeneous supramolecular structure. It was revealed that an increase in dendrite resistance correlates with an improvement in the dielectric characteristics of the composition. The influence of mechanical load on the development of dendrites in polymer dielectrics has been studied. As a result of studying the growth of dendrites in LDPE samples and its optimal composition subjected to unilateral stretching, it was found that under the influence of mechanical tensile stresses, the shape of the surface delimiting tree-like shoots changes, this surface is flattened in the direction of stretching. It has been shown that the rate of dendrite growth increases as mechanical tensile forces increase.

Protective Effect of Quercetin on Amyloid-Induced Alterations in Lipid Bilayer Integrity

Uliana Tarabara — 2024-09-02

The present study employs molecular dynamics simulations to investigate the interactions between quercetin, amyloid fibrils, and POPC lipid bilayers. The results demonstrate that quercetin does not significantly affect the molecular organization of the bilayer, while IAPP fibrils induce substantial structural changes, particularly in the outer monolayer. Quercetin mitigates these effects by reducing the impact on headgroup and glycerol regions and causing a more superficial positioning of IAPP. Additionally, quercetin slightly decreases the order of sn-2 acyl chains, indicating a disordering effect. In a ternary system with POPC, quercetin, and IAPP, the reduction in the deuterium order parameter of sn-2 acyl chains is less pronounced, underscoring quercetin's protective role. Unlike IAPP, ApoAI and insulin fibrils undergo significant structural reorganization in the membrane-bound state. Quercetin attenuative effects are observed only with ApoAI, highlighting its potential as a protective agent against amyloid-induced membrane disruption. These findings provide valuable insights into the interactions between polyphenols, amyloid fibrils, and lipid membranes, contributing to the understanding of membrane-associated amyloid pathologies.

Molecular Docking Study Of Protein-Functionalized Carbon Nanomaterials For Heavy Metal Detection And Removal

Olga Zhytniakivska — 2024-09-02

Carbon nanomaterials (CNMs) have emerged as highly effective agents for the removal of heavy metals from contaminated water and environments, owing to their unique structural and chemical properties. However, the hydrophobic nature of CNMs and their tendency to aggregate in most solvents present significant challenges to their practical application. Functionalizing carbon-based nanomaterials with proteins offers a promising solution to these issues, potentially leading to systems with unprecedented performance. Before fabricating protein-CNM systems for heavy metal detection and removal, it is crucial to evaluate the metal-binding affinity and potential interaction modes using computational approaches. In this study, a molecular docking technique was employed to investigate the interactions among heavy metal salts (AsO₄, Cd(NO₃)₂, Fe(NO₃)₃, NiSO₄, PbSO₄, PtCl₄), carbon-based nanomaterials (fullerenes C₂₄ and C₆₀, and single-walled carbon nanotubes), and β-lactoglobulin. The docking results revealed that: 1) the size, shape, and surface properties of carbon-based materials significantly influence the ability of β-lactoglobulin-CNM complexes to interact with different heavy metals; 2) different heavy metal salts exhibit distinct preferences for the various nanosystems; 3) hydrogen bonding and hydrophobic interactions play a significant role in the complexation of heavy metal salts with β-lactoglobulin-carbon-based materials.

Erratum: Electrıc Fıeld Enhancement by Gold Nano-Sphere and Its Clusters [East European Journal of Physics, 2, 388-393 (2024)]

P.K. Kushwaha — 2024-09-02

The purpose of this Erratum is to correct a misprint presented in the original article.

Erratum: Cosmological Dynamics of Anisotropic Kaniadakis Holographic Dark Energy Model in Brans-Dicke Gravity [East European Journal of Physics, (2), 10-20 (2024)]

A. Vijaya Prasanthi — 2024-09-02

The purpose of this Erratum is to correct a misprint presented in the original article