East European Journal of Physics

A Review of Vacuum-ARC Multilayer Coatings with High-Strength Characteristics and Adhesive Properties

Sun, 08 Dec 2024 00:00:00 +0000

Using the TiSiN/MeN (Me = Cr, Nb, W, Mo, TiZr) coatings system as an example, the analyzed results of multilayer coatings with nanolayers of various functional purposes require a systematic approach to understanding the role of selected materials, growth conditions, microstructure, and required properties. Nanoscale grain boundaries, coherent interlayer boundaries, and changes in columnar morphology at the micro level significantly change the physical and mechanical properties of coatings. For all coatings, an increase in mechanical parameters (hardness, modulus of elasticity) is observed due to the formation of a nanoscale phase (which additionally prevents the movement of dislocations together with nanocomposite TiSiN). In addition, there is a mismatch of crystal lattices between layers. Effectively contributes to strengthening due to variable fields of stresses and strains caused by deformations of elastic coherence. Research has determined optimal conditions for the formation of coatings in a wide range of gas (nitrogen) pressure and shear potential, which also allowed for establishing the factors of structural changes and operational characteristics that will be optimal for their industrial use.

Evolution of Solitary Wave in a Collisionless Quantized Magneto-Plasma with Ion Pressure Anisotropy

Deepsikha Mahanta, Jnanjyoti Sarma — Sun, 08 Dec 2024 00:00:00 +0000

TThis paper presents a comprehensive study in a collisionless plasma composed of charged state of heavy positive ion and light positive as wel as negative ion. By deriving the Korteweg-de Vries (KdV) equation and by using its standard solution we analyze the characteristics of the solitary profile under varying parameters. We found that the solution gives both rarefactive and compressive soliton. The compressive structures are formed for the slow mode, while rarefactive solitary structures are formed for the fast mode. 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 KdV equation.

Taking the Null-Hypersurface Limit in the Parikh-Wilczek Membrane Approach

A.M. Arslanaliev, A.J. Nurmagambetov — Sun, 08 Dec 2024 00:00:00 +0000

We consider subtleties of the horizon (null-hypersurface) limit in the Parikh-Wilczek Membrane Approach to Black Holes. Specifically, we refine the correspondence between the projected Einstein equations of gravity with matter and the Raychaudhuri-Damour-Navier-Stokes (RDNS) equations of relativistic hydrodynamics. For a general configuration of gravity with matter we obtain additional terms in the hydrodynamic equations, which include very specific combinations of the contracted logarithmic derivatives of a parameter (the regularization function) determining the proximity of a stretched membrane to the black hole horizon. Nevertheless, direct computations of the new terms for exact (Schwarzschild and Kerr) black hole solutions prompt the standard form of the RDNS equations, due to the non-expanding horizon property of these solutions. Therefore, the reduction of the extended RDNS equations to their classical form may be viewed as an additional consistency condition in the exact black hole solutions hydrodynamics, and may serve as a non-trivial test for various viable approximations of spacetime metrics. We compare in detail the Parikh-Wilczek Membrane Approach with the Gourgoulhon-Jaramillo method of a null-hypersurface description, as well as give the link of the obtained results to our previous work on the Kerr black holes.

Flat Friedmann-Lemaitre-Robertson-Walker Cosmological Model with Time-Dependent Cosmological Constant in Brans-Dicke Theory of Gravity

Anindita Basumatary, Chandra Rekha Mahanta — Sun, 08 Dec 2024 00:00:00 +0000

Recently, there has been much interest in investigating outstanding problems of cosmology with modified theories of gravity. The Brans-Dicke theory of gravity is one such theory developed by Brans and Dicke absorbing Mach’s principle into the General Theory of Relativity. In Brans-Dicke theory, gravity couples with a time-dependent scalar field ϕ through a coupling parameter ω. This theory reduces to the General Theory of Relativity if the scalar field ϕ is constant and the coupling parameter ω →∞. In this paper, we consider a flat Friedmann-Lemaıtre-Robertson-Walker (FLRW) universe with a time-dependent cosmological constant in Brans-Dicke theory of gravity. Exact solutions of the field equations are obtained by using a power law relation between the scale factor and the Brans-Dicke scalar field ϕ and by taking the Hubble parameter H to be a hyperbolic function of the cosmic time t. We study the cosmological dynamics of our model by graphically representing some important cosmological parameters such as the deceleration parameter, energy density parameter, equation of state parameter, jerk parameter, snap parameter, lerk parameter etc. The statefinder diagnostic pair of the model is also obtained and the validity of the four energy conditions, viz. the Strong energy condition (SEC), Weak energy condition (WEC), Dominant energy condition (DEC) and Null energy condition (NEC), is examined. We find that the universe corresponding to our model is expanding throughout its evolution and exhibits late time cosmic acceleration, which is in agreement with the current observational data.

Non-flat Friedmann-Lemaitre-Robertson-Walker universe with Barrow holographic dark energy

Chandra Rekha Mahanta, Joy Prakash Medhi, Rajashree Mahanta — Sun, 08 Dec 2024 00:00:00 +0000

In this paper, we study a non-flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe filled with cold dark matter and Barrow holographic dark energy. We assume the Hubble horizon as IR cutoff and the scale factor to obey a hybrid expansion law to construct a cosmological model within the framework of General Relativity. The physical and geometrical properties of the model are discussed by studying the evolution of various parameters of cosmological importance. The behaviour of the dark energy equation of state parameter w_DE is also studied for both interacting and non-interacting Barrow holographic dark energy. We observe that the Barrow exponent ∆ significantly affects the dark energy equation of state parameter which in turn exhibits the behaviour of quintessence and phantom dark energy. The evolution of the jerk parameter is also studied.

FLRW cosmological model in f(R,T) gravity

Aroonkumar Beesham — Sun, 08 Dec 2024 00:00:00 +0000

In this paper, the Friedmann-Lemaitre-Robertson-Walker cosmological models with a perfect fluid in the f(R,T) theory of gravity are re-discussed. There are several ways to generate solutions. One way is to assume a barotropic equation of state. The other is to use a deceleration parameter that varies linearly with time. An existing solution in the literature is reviewed, where solutions are obtained by assuming, in addition to a barotropic equation of state, a linear varying deceleration parameter. It is pointed out such an assumption leads to an over-determination of the solution. Hence, the feasibility of the solutions is a necessary condition to be satisfied. Only one of the assumptions of an equation of state or of a linearly varying deceleration parameter is sufficient to generate solutions. The proper solutions are given and discussed.

Nonlinear Ion-Acoustic Solitary Waves in a Weakly Relativistic Electron-Positron-Ion Plasma with Relativistic Electron and Positron Beams

Satyendra Nath Barman, Kingkar Talukdar — Sun, 08 Dec 2024 00:00:00 +0000

In this investigation, compressive and rarefactive solitons are demonstrated to exist in a plasma model that includes unmagnetized weak-relativistic positive ions, negative ions, electrons, electron beam and positron beam. For these weakly relativistic non-linear ion-acoustic waves in unmagnetized plasma with electron inertia and relativistic beam, the existence of compressive and rarefactive soliton is investigated by deriving the Korteweg-de Vries (KdV) equation. It has been observed that the amplitude and width of compressive and rarefactive solitons vary differently in response to pressure variation and the presence of electron inertia. The research determines the requirements that must be met for the existence of the nonlinear ion-acoustic solitons. The fluid equations of motion governing the one-dimensional plasma serve as the foundation for the analysis. Various relational forms of the strength parameter (ε) are chosen to stretch the space and time variables, leading to a variety of nonlinearities. The findings can have implications not only for astrophysical plasmas but also for inertial confinement fusion plasmas.

Numerical Investigation of the Squeezing Flow of Ternary Hybrid Nanofluid (Cu-Al2O3-TiO2/H2O Between Two Parallel Plates in a Darcy Porous Medium with Viscous Dissipation and Heat Source

Rubul Bora, Bidyut Boruah — Sun, 08 Dec 2024 00:00:00 +0000

This work aims to investigate numerically the influence of viscous dissipation and heat source on the magnetohydrodynamics squeezing flow of water-based ternary hybrid nanofluids between two parallel plates in a Darcy porous medium. The nanoparticles Cu, Al₂O₃, and TiO₂ are dispersed in a base fluid H₂O, resulting in the creation of a ternary hybrid nanofluid Cu-Al₂O₃-TiO₂-H₂O. This study examines the deformation of the lower plate as the upper one advances towards it. The numerical results are computed using the 3-stage Lobatto IIIa method, which is specially implemented by Bvp4c in MATLAB. The effects of various parameters are visually illustrated through graphs and quantitatively shown in tables. The absolute skin friction of the ternary hybrid nanofluid is seen to be approximately 5% higher than that of the regular nanofluid at the lower plate and at most 7% higher than that of the nanofluid at the upper plate. The heat transmission rate of the ternary hybrid nanofluid is higher at the upper plate compared to the lower plate.

Thermal Performance of Nanofluid Flow Along an Isothermal Vertical Plate with Velocity, Thermal, and Concentration Slip Boundary Conditions Employing Buongiorno’s Revised Non-Homogeneous Model

Sujit Mishra, Aditya Kumar Pati, Ashok Misra, Saroj Kumar Mishra — Sun, 08 Dec 2024 00:00:00 +0000

This study examines the natural convection of a steady laminar nanofluid flow past an isothermal vertical plate with slip boundary conditions. A review of existing literature reveals no prior research that has explored the combined effects of thermophoresis, Brownian diffusion, and particle electrification while considering slip boundary conditions in nanofluid flow. Buongiorno’s revised four-equation non-homogeneous model, incorporating mechanisms for thermophoresis, Brownian diffusion and particle electrification, is utilized to address this gap. The model employs velocity, thermal, and concentration slip boundary conditions to investigate enhancing the nanofluid's thermal conductivity. The resulting local similar equations are tackled using MATLAB's bvp4c package. The study discusses the influence of key parameters, such as thermophoresis, Brownian motion, and electrification, on temperature, velocity, and concentration distributions, as well as on heat, mass transfer and skin friction coefficients. The findings of the simulation are consistent with previous studies, showing that an improvement in the electrification parameter rises the heat transfer coefficient, while thermophoresis and Brownian motion parameters have the opposite effect. Additionally, mass transfer coefficient values increase with higher Brownian motion and electrification parameters while reducing with the thermophoresis parameter. This physical model has potential applications in heat exchangers using nanofluids and in cooling plate-shaped products during manufacturing processes. The novelty of this study lies in the analysis of Brownian diffusion, thermophoresis, and particle electrification mechanisms in nanofluid flow under slip boundary conditions.

Impact of Anisotropic Permeability on Micropolar Fluid Dynamics and Heat Transfer in Porous Channels

R. Vijaya Sree, V. K. Narla — Sun, 08 Dec 2024 00:00:00 +0000

The current study explores the fluid dynamics and heat transfer characteristics of micropolar fluids within a channel filled with anisotropic porous media. The governing equations for the fluid flow, microrotation, and temperature profiles are numerically solved using Spectral Quasi-Linearization Method (SQLM). The research examines the influence of various key parameters such as the anisotropic permeability ratio, anisotropic angle, Darcy number, Reynolds number, Brinkman number, Prandtl number, and coupling number. Key findings indicate that the anisotropic permeability ratio and anisotropic angle significantly affect fluid flow and heat distribution, with increased anisotropy leading to enhanced microrotation and temperature, albeit with reduced velocity at the channel center. Higher Darcy numbers result in less restricted flow, increasing velocity and reducing microrotation effects, while increasing the coupling number contributes to a more uniform temperature profile. These results provide significant insights into the optimization of heat transfer and flow control in engineering applications that involve micropolar fluids in porous media.

Entropy Generation Optimization in a Ree-Eyring Ternary Hybrid Nanofluid Flow Over an Elastic Surface with Non-Fourier Heat Flux

Sun, 08 Dec 2024 00:00:00 +0000

The significance of Ree-Eyring ternary hybrid nanofluid flow lies in its potential applications in various fields. By incorporating three different types of nanoparticles into a base fluid using the Ree-Eyring model, this innovative fluid offers enhanced thermal conductivity, heat transfer efficiency, and rheological properties. These characteristics are particularly valuable in industries such as electronics cooling, solar energy systems, and heat exchangers, where efficient heat management is crucial. Additionally, the unique rheological behavior of Ree-Eyring nanofluids can provide advantages in processes like drilling, lubrication, and drug delivery. Under Thompson-Troian boundary conditions, this study aims to theoretically analyse 2D radiative flow of the Ree-Eyring ternary hybrid nanofluid over an angled sheet with Cattaneo-Christov heat flux and higher order chemical reaction parameters. In order to express them as ordinary differential equations (ODEs), flow-driven equations undergo suitable similarity transformations. The ensuing system is resolved by employing a bvp4c approach. The main takeaway from this study is that the thermal relaxation parameter reduces the width of the temperature profile and the fluid velocity is minimized by adjusting the slip parameter. The concentration profile is minimized by the chemical reaction parameter and the Ree-Eyring fluid parameter increases with the same (fluid velocity). In addition, we found that the skin friction coefficient is strongly correlated negatively with the Ree-Eyring fluid parameter, positively with the (thermal) relaxation parameter, and significantly correlated positively with the chemical reaction through the Nusselt number. When Brinkman number increases, Bejan number drops. Furthermore, a rise in thermal radiation parameter leads to the escalation in both entropy generation and Bejan number. We observed a worthy agreement when we checked the outcomes of this investigation with prior effects.

Radiation Effect on MHD Free Convective Flow Past a Semi-Infinite Porous Vertical Plate Through Porous Medium

Sweety Sharma, Kangkan Choudhury, Harun Al Rashid — Sun, 08 Dec 2024 00:00:00 +0000

The study of MHD heat and mass transfer dissipative free convective flow past a semi-infinite porous vertical plate through porous medium in presence of thermal radiation is considered. The novelty of the present work is to examine radiation effect (Rosseland Approximation) on the flow transport characteristics. The equations governing the flow of heat and mass transfer are solved by asymptotic series expansion method to evaluate the expressions for velocity, temperature, concentration fields, skin-friction, rate of heat and mass transfer. The influence of various physical parameters on the flow is discussed through graphs and in tabular form. It is found that an increase in radiation parameter to decrease the velocity and temperature. Further, it is seen that the skin -friction at the plate decreased with increasing values of radiation parameter.

Radiative Effect on an Unsteady Darcy Forchheimer MHD Flow Over a Vertically Inclined Stretching Sheet in Presence of Porous Medium

Ankur Kumar Sarma, Sunmoni Mudoi, Palash Nath, Pankaj Kalita, Gaurabh Bardhan — Sun, 08 Dec 2024 00:00:00 +0000

This study looks at how radiation and heat move through a two-dimensional, unsteady Darcy-Forchheimer MHD flow that flows across a porous, stretched plate that is vertically inclined and has a transverse magnetic field applied to it. We use the MATLAB bvp4c approach to numerically translate the controlling boundary layer nonlinear PDEs, which are partial differential equations, into a set of nonlinear ODEs, which are ordinary differential equations, using the similarity transformation. We quantitatively assess the velocity and temperature profiles using graphs that represent the problem's various characteristics, including unsteadiness, Prandtl number, magnetic, Grashoff number, radiation parameter, and Eckert number. Tables illustrate the effects on skin friction () and Nusselt number (Nu). The velocity profile decreases as the magnetic and inertial parameters increase, and the temperature profile decreases with the increases in the radiation parameters.

Chemical Reaction, Electrification, Brownian Motion and Thermophoresis Effects of Copper Nanoparticles on Nanofluid Flow with Skin Friction, Heat and Mass Transfer

Sun, 08 Dec 2024 00:00:00 +0000

This study investigates the effects of first-order chemical reaction, thermophoresis, electrification, and Brownian motion on nanoparticles within a free convective nanofluid flow past a vertical plane surface, focusing on skin friction, heat and mass transfer. The unique combination of chemical reaction and electrification effects sets this study apart from previous research on nanofluid flow. By utilizing similarity functions, the governing PDEs of the flow are converted into a system of locally similar equations. These equations are then solved using MATLAB's bvp4c function, incorporating dimensionless boundary conditions. The findings are verified through a comparison with previous studies. Graphical illustrations show the numerical explorations for concentration, velocity, and temperature profiles in relation to the electrification parameter, thermophoresis parameter, chemical reaction parameter, and Brownian motion parameter. The computational results for heat transfer, mass transfer and dimensionless skin friction coefficients are presented in tabular form. The primary finding indicates that the electrification parameter accelerates heat transfer, while the electrification parameter, Brownian motion parameter, and chemical reaction parameter enhance the rate of mass transfer from the plane surface to the nanofluid. This indicates encouraging potential for cooling plane surfaces in manufacturing industries.

A Biomagnetic Couple Stress Fluid Flow in an Anisotropic Porous Channel with Stretching Walls

R. Vijaya Sree, V. Krishna Narla, K. Suresh Babu — Sun, 17 Nov 2024 18:23:34 +0000

The present study investigates the dynamics of a biomagnetic couple stress fluid within an anisotropic porous channel where the channel walls are stretchable. This study examines the flow behavior under the influence of an external magnetic field generated by a magnetic dipole. Appropriate dimensionless parameters are introduced to simplify the equations of the problem. A suitable numerical approach based on the Spectral Quasi-Linearization Method is utilized to obtain a solution to the problem. In this work, influence of several important parameters like the anisotropic permeability ratio, couple stress parameter, anisotropic angle, Darcy number, ferromagnetic interaction parameter, Reynolds number, and Prandtl number are examined. The results indicate that ferromagnetic interaction parameter and couple stress parameter significantly impact heat transfer and fluid flow. Permeability ratio and angle also affect the flow dynamics. Furthermore, the coefficient of skin friction and rate of heat transfer were examined, varying the couple stress and ferromagnetic interaction parameters. The findings demonstrate that an existence of magnetic dipole and anisotropic permeability significantly influences the flow and thermal properties of ferrofluids, providing valuable insights for optimizing heat transfer and controlling fluid flow in diverse engineering and medical applications.

Magneto Hydrodynamic and Bio-Convection Effects on Hybrid Nanofluid Dynamics Over an Inverted Rotating Cone with Different Base Fluids

Balaji Padhy, Archana Senapati, Goutam Kumar Mahato, P.K. Rath — Sun, 08 Dec 2024 00:00:00 +0000

This study explores the combined effects of magnetohydrodynamics (MHD) and bio-convection on the flow dynamics of hybrid Nanofluids over an inverted rotating cone with different base fluids. The hybrid Nanofluids, composed of nanoparticles suspended in various base fluids, exhibit unique thermal and flow characteristics due to the interplay between magnetic fields and bio-convection phenomena. The governing equations, incorporating the principles of MHD and bio-convection, are derived and solved using numerical methods. The analysis considers the impact of key parameters such as magnetic field strength, the rotation rate of the cone, nanoparticle volume fraction, and types of base fluids on the flow behaviour, heat transfer, and system stability. Results indicate that the MHD significantly influences the velocity and temperature profiles of the hybrid Nanofluids, while bio-convection contributes to enhanced mixing and heat transfer rates. Additionally, the choice of base fluid plays a critical role in determining the overall performance of the hybrid Nano fluid system. This study provides valuable insights into optimizing the design and operation of systems utilizing hybrid Nanofluids in applications where MHD and bio-convection effects are prominent.

Heat Generation Effect on 3D MHD Flow of Casson Fluid Via Porous Stretching/Shrinking Surface with Velocity Slip Condition

Nainaru Tarakaramu, B. Jagadeesh Kumar — Sun, 08 Dec 2024 00:00:00 +0000

There are extensive range of applications related to nuclear industry, industrial manufacturing, science and engineering processing, in which the boundary layer hydromagnetic motion of Casson liquids perform vital role. Casson liquid is a useful liquid in the nuclear industry for optimizing the design and operation of nuclear reactors. Researchers have investigated transfer of heat in liquid motions with linear stratification, which is a phenomenon where the temperature varies linearly with height, affecting various fields such as medical equipment, glass fiber production, electronic devices, polymer sheets, paper production, filaments, and medicine. However, the most discussion of heat transfer problems is to get numerical solutions of a comprehensive Casson liquid model with heat generation described by the BVP4 via shooting method. In this study, a new velocity slip boundary condition is applied at the stretching or shrinking surface. These conditions are grounded in the previously established Buongiorno model, providing a more practical and realistic approach compared to previous study. The time independent Gov. Eqs. changed into a set of couple non-linear ODEs with help of suitable similarity conversions. The equations are evaluating via R-K-F by help of MATLAB software programming.

Understanding The Projectile Breakup Mechanism Using Monte Carlo Simulation Technique

Mon, 18 Nov 2024 18:18:40 +0000

A montecarlo modeling simulation has been performed to understand the breakup bellow the barrier and for 7Li+208Pb reaction. A wider detection cone has been found for near target breakup compaired to assomptotic breakup. The exclusive coincidence particle spectrum for alpha and triton has also simulated and found the breakup from difeerent resonant state. The data has also represented.A classical approach has been adopted to understand the reaction meachanism.

Study of the Coulomb Nuclear Interference of 23Al Breakup Reaction with Different Targets

Surender, Ravinder Kumar — Sun, 08 Dec 2024 00:00:00 +0000

The impact of Coulomb-diffraction interference on the one-proton removal breakup cross-section and the width of the longitudinal momentum distribution (LMD) has been investigated for the breakup reaction of the $^{23}$Al nucleus with different light to the heavy target for energy 40-100MeV/nucleon. Sensitivity to the target size and incident energy was analyzed through calculations that incorporate Coulomb interactions to all orders, including the full multipole expansion and nuclear diffraction using the eikonal approximation in the Glouber model. The results indicate that both constructive and destructive interferences significantly impact the observables, with the effects being more pronounced for medium-mass targets than light or heavy targets.

Effect of Sintering Temperature on Microstructure and Properties of Zirconia Ceramics for the Needs of Nuclear Energy

Sun, 08 Dec 2024 00:00:00 +0000

The paper provides experimental results of obtaining high-density ZrO₂+3%Y₂O₃ ceramics, which is promising for use as a matrix for immobilization of HLW. The effect of sintering temperature in the range of 1100...1650 °C on the microstructure of the sintered tablets was studied. Phase composition and microstructure of experimental samples were characterized by XRD and SEM. Grain size distribution analysis was carried out using the "Thixomet" image analyzer. Microhardness was determined using a metallographic complex LECO (USA), an inverted microscope IM-3MET and a hardness tester UIT HVB-30. It was established that increase in the sintering temperature leads to a significant increase in the average grain size (from 85 nm to 1000 nm) and increase in the density of the sintered tablets. Sintering temperature should be at least 1550...1650 ºС to produce high-dense ceramics (97...98 % of theoretical value). Obtained ceramics is characterized by high values of microhardness HV > 12 GPa and crack resistance of 5.5...6.3 MPa·m^1/2.

Operation Experience of Westinghouse Nuclear Fuel at Ukrainian NPPs

Valeriy Zuyok, Roman Rud, Mykhaylo Tretyakov, Yana Kushtym, Vadym Hrudnytskyy — Sun, 08 Dec 2024 00:00:00 +0000

To ensure compatibility with the more robust design of TVSA manufactured by TVEL JSC, a modification of the Westinghouse FA, referred to as RWFA, was announced in 2013, which was designed to be more robust. Since 2015, RWFAs has been in pilot operation and since 2019 in commercial operation in Ukraine. The supply of Westinghouse FAs to Ukraine was under constant supervision and integrity control at all stages of operation and after its end. From the very beginning of the implementation of the WFAs, specialists of SE "NNEGC "Energoatom" and Westinghouse Company with the scientific support of NFC STE NSC KIPT carried out the annual inspections of the fuel assemblies. Based on the inspection results of 86 WFAs/RWFAs after 1-3 years of operation, it was concluded that the obtained values of the parameters characterizing the integrity of WFAs/RWFAs did not exceed the limits set during the FA design and safety substantiation of the core loading where those FAs were operated. All FAs that were subjected to scheduled inspections were loaded in the subsequent fuel cycles.

Elastic Properties of C-Type Lanthanide Sesquioxides

Sun, 08 Dec 2024 00:00:00 +0000

In this study, we have presented the solid-state theory of plasma oscillations to investigate the anisotropic elastic properties such as three independent static elastic stiffness constants (C_ij: C₁₁, C₁₂ & C₄₄) of C-type Ln₂O₃ lanthanide solids. The calculated values of the static elastic stiffness constants of Ln₂O₃ are in excellent agreement with the theoretical results obtained by using ab-initio techniques. The values of elastic stiffness constants (C_ij) exhibit a linear relationship when plotted against their plasma energies and lie on a straight line. To further examine the validity of the present estimations on elastic moduli and other parameters of these materials. The mechanical moduli such as bulk modulus (B), shear modulus (G), Young modulus (E), Poisson’s ratio (ν), shear wave constant (C_s), Cauchy pressure (C^*), Lame’s coefficient (λ and µ), Kleinman parameter (ξ) Grunesien parameter (γ), Zener anisotropic constant (Z) and Pugh ratio (G/B) of lanthanide solids have also been investigated. For the lanthanide sesquioxide materials, the values of static elastic stiffness constants C_ij and elastic moduli were presented for the first time. Unfortunately, in the current study, for many parameters of these materials, experimental results were not found for a comparison with our theoretical predictions. Our estimations agree well with the available experimental data and other theoretical reports.

Electronic, Structural, Optical and Mechanical Properties of Cubic Structured Ln2X3 (Ln = La→Lu & X=O,S): An Empirical Investigation

Sun, 08 Dec 2024 00:00:00 +0000

In this publication, we have examined the structural, optical, and mechanical features of cubic structured lanthanide Ln₂X₃ (Ln = La→ Lu and X = O, S) series using the valence electron plasma oscillation theory of solids. Using the Chemical bond theory of solids, which was created by Phillips and Van-Vechten, we have further confirmed our findings. Unfortunately, it has been discovered that the Phillips and Van-Vechten (PVV) dielectric description is applicable exclusively to semiconductors and insulators. It is shown that an empirical relationship previously presented by Yadav and Bhati [D.S. Yadav, J. Alloys and Comp. 537, 250 (2012); D.S. Yadav, and D.V. Singh, Phys. Scr. 85, 015701 (2012); D.S. Yadav, J. Mater. Phys. Chem. 3(1), 6-10 (2015); R. Bhati, et al., Mater. Phys. Mech. 51, 90 (2023); R. Bhati, et al., East Eur. J. Phys. (1), 222 (2023).] relating the plasmon energy of complex structured solids, rock salt, and zinc-blende to their electronic, mechanical, static, and dynamical properties which can be applied to the cubic structured lanthanide (Ln₂S₃ & Ln₂O₃) series with only minor modifications. Considering the well-known theory of dielectric for solids, an alternative technique has been devised to evaluate the electronic, structural, mechanical, and optical properties of these materials, including their band gap (∆E_g in eV), optical dielectric constant, homopolar and heteropolar gaps, average energy gaps, chemical bond ionicity, and bulk muduli. An estimate was computed based on the almost inverse relationship between the plasmon energy of these compounds and their optical, mechanical, structural, and electrical characteristics. For these substances, the expected values of the aforementioned parameters form a straight line when plotted on a log-log scale against the plasmon energy (ħω_p). We examined the C‑type Ln₂X₃ compounds using the recommended methods, and the values we estimated are in good agreement with the values obtained from modified PVV theory and other comparable experimental and theoretical data that is currently available.

Changes in the Structure and Properties of Silicon During Ytterbium Doping: The Results of o Comprehensive Analysis

Sun, 08 Dec 2024 00:00:00 +0000

In this work, a comprehensive study of the structural, chemical and electrophysical properties of monocrystalline silicon (Si) doped with ytterbium (Yb) has been carried out. The alloying was carried out by thermal diffusion at a temperature of 1473 K in high vacuum conditions followed by rapid cooling. Atomic force microscopy (AFM), infrared Fourier spectroscopy (FTIR), deep level spectroscopy (DLTS) and Raman spectroscopy (RAMAN) were used to analyze the samples obtained. AFM images of the surface of the doped samples demonstrated significant changes in topography. The RMS surface roughness increased from less than 10 nm to 60-80 nm, and the maximum height of the irregularities reached 325 nm. These changes are explained by the formation of nanostructures caused by the uneven distribution of ytterbium atoms in the silicon crystal lattice, as well as the occurrence of internal stresses. "IR-Fourier spectroscopy showed a significant decrease in the concentration of optically active oxygen (N_O^opt ) by 30-40% after doping. This effect is associated with the interaction of ytterbium atoms with silicon and a change in the chemical composition of the material. The RAMAN spectra revealed the formation of new phases and nanocrystallites in the doped samples. Peak shifts and changes in their intensity were detected, indicating a rearrangement of the crystal lattice caused by the introduction of ytterbium. It was calculated that the diffusion coefficient of ytterbium in silicon is 1.9×10^-15 cm²/s, which indicates a slow diffusion process characteristic of rare earth metals. Electrical measurements carried out on the MDS-structures showed a shift in the volt-farad characteristics towards positive bias voltages, which is associated with a decrease in the density of surface states at the Si-SiO₂ interface and the appearance of deep levels with an ionization energy of E_c-0.32 eV.

Investigation of Morphological and Optical Properties of LiNbO3 and LiNbO3:Fe 0.03 wt.% Crystals

Sun, 08 Dec 2024 00:00:00 +0000

This article is devoted to the morphological and optical properties of the photorefractive crystal LiNbO₃ and LiNbO₃:Fe 0.03 wt.%. According to it, the surface morphology of the samples was studied using an atomic force microscope (AFM). In addition, ordinary and extraordinary refractive indices of the LiNbO3 crystal were calculated using empirical formulas. The results of the diffraction efficiency of the LiNbO₃:Fe 0.03 wt.% crystal for He-Ne and He-Cd lasers are presented.

Volt-Ampere Characteristics of Hetero Film Photosensitive Structure Au-CdS-nSi-CdTe-Au

Sun, 08 Dec 2024 00:00:00 +0000

The results of studies of the current-voltage characteristics of a photodiode heterostructure are presented. Au-nCdS-nSi-pCdTe-Au, in forward and reverse directions. Photodiode heterostructures with an area of 29 mm2 were created, which were obtained by vacuum evaporation in a quasi-closed volume by depositing layers of cadmium sulfide and cadmium telluride onto a single-crystalline silicon substrate with resistivity ρ = 607.47 Ohm∙cm. A distinctive feature of the resulting photodiode Au-nCdS-nSi-pCdTe-Au structures is two-way sensitivity, where impurity complexes are formed. In the structures, the rate of recombination of nonequilibrium carriers at low excitation levels is determined by simple local centers in the boundary transition layers. The band diagram of a multilayer photodiode structure Au-nCdS-nSi-pCdTe-Au has been constructed.

Exploring the Elastic, Magnetic, Thermodynamic and Electronic Properties of XNNi3 (X: Cd, In) Cubic Anti-Perovskites

Jounayd Bentounes, Amal Abbad, Wissam Benstaali, Kheira Bahnes, Noureddine Saidi — Sun, 08 Dec 2024 00:00:00 +0000

Density functional theory is used to investigate the structural, electronic, thermodynamic and magnetic properties of the cubic anti-perovskites InNNi₃ and CdNNi₃. Elastic and electronic properties were determined using generalized gradient approximation (GGA) and local spin density approximation (LSDA) approaches. The quasi-harmonic Debye model, using a set of total energy versus volume calculations is applied to study the thermal and vibrational effects. The results show that the two compounds are strong ductile and satisfy the Born-Huang criteria, so they are mechanically stable at normal conditions. Electronic properties show that the two compounds studied are metallic and non-magnetic. The thermal effect on the bulk modulus, heat capacity, thermal expansion and Debye temperature was predicted.

Structural, Dielectric and Magnetic Properties of Epitaxial Grown YMn0.5Cr0.5O3 thin films

A. Rambabu, G. Jeevana Mounika, K. Jayadev, B. Sridhar — Sun, 08 Dec 2024 00:00:00 +0000

YCr_(1-x)Mn_xO₃is an intriguing member of the perovskite family, attracting significant interest due to its versatile properties and potential applications in various fields. Epitaxial orthorhombic YMn_0.5Cr_0.5O₃films are grown on STO substrates by pulsed laser deposition method. Well crystalline with (0 ℓ 0) orientation of YMn_0.5Cr_0.5O₃films are identified by X-ray diffraction. Field emission scanning electron microscopy used to capture the morphological behavior of crystalline YMn_0.5Cr_0.5O₃films. Temperature-dependent dielectric properties are analyzed thoroughly. The magnetic properties of YMn_0.5Cr_0.5O₃films are characterized using physical property measurement system. There is a clear magnetic transition observed around 60K for three YMn_0.5Cr_0.5O₃films. Films deposited at 600^oC exhibited high dielectric and magnetic properties.

Mechanism of Current Performance in Thin-Film Heterojunctions n-CdS/p-Sb2Se3 Obtained by the CMBD Method

Sun, 08 Dec 2024 00:00:00 +0000

In this work, we analyzed the temperature dependence of the current-voltage characteristics of the structure of glass/Mo/p-Sb₂Se₃/n-CdS/In. From an analysis of the temperature dependences of the direct branches of the I-V characteristic of the heterojunction, it was established that the dominant mechanism of current transfer at low biases (3kT/e<V<0.8V) is multi-stage tunneling-recombination processes involving surface states at the Sb₂Se₃/CdS interface. At V>0.8 V, the dominant current transfer mechanism is Newman tunneling. In the case of reverse bias (3kT/e<V<1.0 eV), the main mechanism of charge carrier transfer through a heterojunction is tunneling through a potential barrier involving a deep energy level. At higher reverse voltages, a soft breakdown occurs.

Impact of Sulfur Concentration on the Magnetic and Electrical Characteristics of ZnMnO Thin Films

Azamat O. Arslanov, Shavkat U. Yuldashev, Younghae Kwon, Ahn Il-Ho — Sun, 08 Dec 2024 00:00:00 +0000

Influence of the sulfur doping on the structural, optical, electrical and magnetic properties of ZnMnO thin films fabricated using the ultrasonic spray pyrolysis technique was investigated. Our study reveals that increasing sulfur content leads to a noticeable shift in the band gap energy towards the red spectrum, an indicator of altered electronic states and potential for enhanced spintronic functionalities. The strong reduction in the band gap for the sulfur doped ZnMnO alloys is the result of the upward shift of the valence-band edge. As a result, the room temperature bandgap of ZnMnO_1-xS_x alloys can be tuned from 3.2 eV to 2.97 eV for x ≤ 0.2. The observed large bowing in the composition dependence of the energy bandgap arises from the anticrossing interactions between the valence-band of ZnO and the localized sulfur level above the ZnMnO valence-band maximum. The doping process significantly modifies the ferromagnetic properties, with an observed increase in Curie temperature correlating with higher sulfur concentrations. These changes are attributed to the increased free holes concentration, which facilitates a more robust exchange interaction between the magnetic ions. Additionally, the structural assessments via scanning electron microscopy confirm the uniform integration of sulfur into the ZnMnO matrix, resulting in distinct nanocrystalline formations. This study contributes to the understanding of doping mechanisms in semiconductor materials, especially for highly mismatched alloys, where the anions are partially substituted with isovalent atoms of considerably different size and/or electronegativity, offering insights into the tunability of their magnetic and electronic properties for potential future applications in spintronic devices.

Influence of Boron Diffusion on Photovoltaic Parameters of n+-p-p+ Silicone Structures and Based Photodetectors

Mykola S. Kukurudziak, Eduard V. Maistruk, Ivan P. Koziarskyi — Wed, 20 Nov 2024 15:03:09 +0000

The paper investigates the photovoltaic properties of the silicon n⁺-p-p⁺-structures and photodiodes made on their basis. It was found that boron diffusion to the reverse side of the substrate, in addition to creating an ohmic contact, generates generation-recombination centers, which allows to reduce the dark current of photodiodes and increase their responsivity. It was also found that chemical dynamic polishing of the back side of the substrates before boron diffusion allows to eliminate a significant number of defects and improve the final parameters of the products. In samples without a p⁺-layer and samples not polished from the back side, a breakdown of the p-n junction is observed on the back side, which is caused by the expansion of the space charge region to the entire thickness of the substrate and the achievement of a defective back side of the crystal.

The Surface Layer Morphology of Si Samples

M.Sh. Isaev, A.I. Khudayberdieva, M.N. Mamatkulov, U.T. Asatov, S.R. Kodirov — Sun, 08 Dec 2024 00:00:00 +0000

In this work, the electrical and photoelectric properties of the near-surface and surface layers of silicon doped by diffusion with chromium atoms were investigated. The formation of an anomalous concentration of charge carriers in these regions, as well as an anomalously low mobility, was revealed. The specific conductivity of the near-surface layer with a thickness of 1÷5 µm turned out to be equal to (1.6÷9.9)·10³ Ohm^-1·cm^-1. The inhomogeneity of the crystal under study was determined by the light probe method.

Defect Formation in MIS Structures Based on Silicon with an Impurity of Ytterbium

Sun, 08 Dec 2024 00:00:00 +0000

The characteristics of silicon MIS structures with ytterbium impurity are studied using non-stationary capacitance spectroscopy of deep levels. It is established that the presence of ytterbium atoms in the bulk of the silicon substrate leads to a shift in the capacitance-voltage characteristics towards positive bias voltages and a decrease in the density N_ss of the surface states of the MIS structures. It is shown that this effect depends on the concentration of ytterbium atoms in the silicon substrate of the studied structures. In MIS structures based on Si<Yb>, one deep level with an ionization energy E_c-0.32 eV is detected.

Current Mechanisms in Zinc Diffusion-Doped Silicon Samples at T = 300 K

Sun, 08 Dec 2024 00:00:00 +0000

This work is devoted to the study of current flow in diffusion-doped zinc silicon samples in the dark and when illuminated with light with an intensity in the range from 0.6 to 140 lx and at a temperature of 300 K. At T = 300 K and in the dark, the type of the I–V characteristic contained all areas characteristic of semiconductors with deep energy levels. It was found that when illuminated with light, the type of I–V characteristics of the studied Si samples depended on the value of the applied voltage, the electrical resistivity of the samples, the light intensity, and their number reached up to 6. In this case, linear, sublinear, and superlinear sections were observed, as well as the switching point (sharp current jump) and areas with negative differential conductivities (NDC). The existence of these characteristic areas of the applied voltage and their character depended on the intensity of the light. The experimental data obtained were interpreted in the formation of low dimensional objects with the participation of multiply charged zinc nanoclusters in the bulk of silicon. They changed the energy band structure of single-crystal silicon, which affected generation-recombination processes in Si, leading to the types of I–V characteristics observed in the experiment.

Study of Defect Structure of Silicon Doped with Dysprosium Using X-Ray Phase Analysis and Raman Spectroscopy

Sun, 08 Dec 2024 00:00:00 +0000

In this paper, the effect of doping silicon with dysprosium (Dy) on its structural and optical characteristics is investigated. Silicon n-Si was doped with dysprosium by thermal diffusion at 1473 K for 50 h. Raman spectroscopy and X-ray diffraction analysis were used for the analysis. The Raman spectroscopy results showed a main peak at 523.93 cm⁻¹, corresponding to n-Si optical phonons, with an increase in the intensity and full width at half maximum (FWHM) in n-Si<Dy> samples, indicating an improvement in the crystallinity of the structure. A decrease in the intensity of the peaks at 127.16 cm⁻¹ and 196.24 cm⁻¹, associated with amorphous structures, confirms a decrease in defects. The detection of a new peak at 307.94 cm⁻¹ indicates successful deposition of dysprosium as nanocrystallites associated with the 2TA phonon mode in the cubic phase of Dy₂O₃. X-ray diffraction analysis revealed characteristic structural lines indicating the (111) crystalline orientation and the presence of microdistortions in the lattice. Heat treatment and rapid cooling lead to a change in the intensity of structural lines, an increase in the second- and third-order lines, which indicates microstrains and a change in the size of subcrystallites. Doping of silicon with dysprosium improves the crystallinity of the structure, reduces the number of defects and forms polycrystalline layers on the surface consisting of SiO₂ and Dy₂O₃ nanocrystals.

Energy of Crystal Lattice Thermal Oscillations in TlGaS2 Semiconductor Compound

Sun, 08 Dec 2024 00:00:00 +0000

This article presents the results of a study of the temperature dependences of the coefficients of thermal expansion and isothermal compressibility of the ternary compound TlGaS₂. In the studied temperature range (80-400 K), no anomalies were found in the temperature dependences of these properties. The thermal expansion coefficient of the TlGaS₂ semiconductor compound is calculated based on empirical formulas including Debye temperature and Debye functions, and the average energy of the crystal lattice is calculated and its temperature dependence is tabulated. It was shown that the energy of the crystal lattice depends on the degree of anharmonicity of the oscillations.

Factors Influencing the Ideality Factor of Semiconductor p-n and p-i-n Junction Structures at Cryogenic Temperatures

Jo`shqin Abdullayev, Ibrokhim B. Sapaev — Sun, 08 Dec 2024 00:00:00 +0000

This article elucidates the dependence of the ideality factor on both internal functional parameters and external factors in semiconductors at low temperatures. We have explored the influence of external factors such as temperature and external source voltage. Through numerical modeling and theoretical analysis, we thoroughly investigate the dependencies of semiconductor material internal functional parameters—including doping concentration, the bandgap of semiconductors, the lifetime of charge carriers, and geometric dimensions ranging from micrometers to nanometers— the ideality factor on p-n and p-i-n junction structures. Our analysis spans cryogenic temperatures from 50 K to 300 K, with intervals of 50 K. To conduct this study, we have focused on p-n and p-i-n junction structures fabricated from Si and GaAs. The selected model features geometric dimensions of a=10 μm, b=8 μm, and c=6 μm. The thickness of the i-layer ranged from 10 µm to 100 µm in 10- µm increments. Increasing the thickness of the i-layer results in a corresponding rise in the ideality factor.

Scale Modeling of the Influence of Multiple Localized Defects of Metal Surface on Optical Ellipsometry Results

Oleksii Haluza, Ivan Kolenov, Iryna Gruzdo — Sun, 08 Dec 2024 00:00:00 +0000

The work is devoted to the problem of ellipsometric studies of real surfaces and considers the case when surface inhomogeneities are individual localized defects or conglomerates with a size comparable to the wavelength of the probing radiation. Such inhomogeneities lead to angular dependences of ellipsometric parameters that have a non-classical form and cannot be described using conventional well-known models of homogeneous planar layers. This work focuses on the influence of conglomerates of localized defects on the angular dependences of ellipsometric parameters and serves as a continuation of earlier studies in which single localized defects were considered. The dependence of the degree of influence of the distance between defects on the ellipsometric parameters is examined. The parameter “critical distance” between defects is introduced, beyond which they can be considered as localized, and estimates of this parameter for the considered configurations are provided.

Magneto-Optics Features of Radiation Transitions of Non-Kramers Tm3+ Ion in Yttrium-Aluminum Garnet Crystals

Furkat K. Turotov, Mariya E. Malysheva, Ramil R. Vildanov — Sun, 08 Dec 2024 00:00:00 +0000

The spectra of luminescence and magnetic circular polarization of a single crystal of thulium-yttrium garnet-aluminate Tm³⁺:YAG have been studied within the visible spectral range at a temperature of 90 and 300 K in a magnetic field of 10 kOe. Based on the analysis of optical and magneto-optical data, the presence of "quasi-degenerate" states of excited multiplets ¹D₂,³F₄,³G₄ and the ground multiplet ³H₆ of the Tm³⁺RE ion in garnet-aluminate YAG at the radiative transitions ¹G₄→³H₆, ¹D₂→³F₄ and ¹D₂→³F₃ has been determined. The effect of quantum mechanical “mixing” plays a significant role in the occurrence of magneto-optical effects on luminescence bands caused by “forbidden” 4f→4f transitions in the non-Kramers Tm³⁺ ion having a “quasi-doublet” structure in the energy spectra.

Unveiling the Potential of Double Perovskite Halides Rb2CuSbH6 (H = Cl, Br, I) for Flexible Electronics: An Integrated Study of Structural, Mechanical, Electrical and Optical Properties

Krishna Kumar Mishra, Sonia Chahar, Rajnish Sharma — Sun, 08 Dec 2024 00:00:00 +0000

The structural, mechanical, electrical and optical properties of double perovskite halides like Rb₂CuSbH₆ (where H = Cl, Br, and I) for flexible electronic devices are fascinating and complex. Extensive literature survey clearly establishes that there has been limited research on analyzing the potential uses of these materials for the highly sought-after sector of flexible electronic devices. In this paper, focused studies have been carried out on investigating the characteristics of these materials using QuantumATK NanoLab Software Tool. All double perovskite halides Rb₂CuSbH₆ (H = Cl, Br, I) show positive values for the elastic constants C₁₁, C₁₂, and C₄₄, and obey the stability trend C₁₁>C₁₂>C₄₄. Mechanical stability was established using Born-Huang criteria. Optimized values of Young's modulus, bulk modulus, shear modulus and Poisson ratios established that materials are stable and ductile in nature. While carrying out analysis of electronic properties, all three materials Rb₂CuSbCl₆, Rb₂CuSbBr₆, and Rb₂CuSbI₆ were found to be possessing indirect energy bandgap of 0.924 eV, 0.560 eV, and 0.157 eV, respectively. Moreover, the Complex Bandstructure (CB) naturality indicates that most evanescent wave may exist when layer separation is lowest in Rb₂CuSbCl₆ (6.0 Å), Rb₂CuSbBr₆ (6.33 Å), and highest in Rb₂CuSbI₆ (6.8 Å). Absorption bands for Rb₂CuSbCl₆, Rb₂CuSbBr₆ and Rb₂CuSbI₆ lie in the visible range with 344 nm to 574 nm, 348 nm to 688 nm and 369 nm to 608 nm respectively. The reflectivity (r) reported under this study is 0.105, 0.139 and 0.185 respectively for Rb₂CuSbCl₆, Rb₂CuSbBr₆ and Rb₂CuSbI₆. Overall, all the obtained results implicate toward need to explore the Rb₂CuSbH₆ materials in more depth for variety of electronic device applications.

Obtained and Studied Structural Aspects of the Ge0.9Er0.1S Compound with Ge → Er Substitutions

R.Z. Ibaeva, G.B. Ibragimov, A.S. Alekperov, R.E. Huseynov — Sun, 08 Dec 2024 00:00:00 +0000

In this work, Ge_0.9Er_0.1S was synthesised by partially replacing Ge atoms with Er atoms. The crystal structure of the resulting compound was studied by X-ray diffraction. The research found that Er atoms can completely replace Ge atoms in the crystal structure. Therefore, the compound can crystallize into one phase. It was established that the structure of this compound corresponds to orthorhombic symmetry and space group Pnma. The crystallographic parameters of the Ge_0.9Er_0.1S compound were determined by analyzing the X‑ray diffraction spectrum using the Rietveld method. Based on the obtained structure on different atomic planes, an explanation of the crystal structure of the Ge_0.9Er_0.1S semiconductor is given. It is established that one of the main elements in the formation of the crystal structure are the ionic radii of the elements Ge, Er and S.

Studies of the Impact of UV on CMC PVA/ZnO Nanocomposite Films Prepared with a Simple Solution Casting Method

Abdelhedi Aydi, Sarah A. Ibrahim, Abderrazek Oueslati — Sun, 08 Dec 2024 00:00:00 +0000

The synthesis of nanocomposite films comprising carboxymethyl cellulose/ polyvinyl alcohol (CMC PVA) mixed with zinc oxide nanoparticles (ZnO NPs) through a simple solution casting method is examined. Furthermore, the impact of ZnO NPs and UV‑irradiation exposure for varying durations (20,45,75h) on the morphology (FE-SEM) is investigated. The X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and ultraviolet-visible (UV-Vis) spectroscopy are utilized to analyze the as-prepared films. Furthermore, the field-emission scanning electron microscopy (FE-SEM) images reveal a noticeable change in the morphology of CMC PVA/ZnO nanocomposite films attributed to the significant impact of ZnO nanoparticles and UV exposure. The XRD spectra demonstrate a modification in the amorphous phase of the samples as a result of UV exposure The FTIR analysis reveals that the exposure to UV radiation positively influenced the polymer's structure, as evidenced by notable changes in the infrared peaks. Additionally, the UV-Vis spectroscopy results indicate that longer UV exposure times (75 hours) and the addition of ZnO nanoparticles resulted in improved absorption characteristics within the produced films. The nanocomposite films displayed an adjustable energy gap (Eg) that varied between (4.52 eV and 4.55 eV) as the duration of UV irradiation increased from (20 hours) (75 hours) led to a reduction in the energy gap (Eg) value to (4.50 eV). This phenomenon is believed to be caused by the substantial influence of UV radiation on the development of structural defects. Ultimately, the Energy gap Eg of the nanocomposite films was influenced by the duration of UV. The results demonstrate that there is significant potential for the utilization of CMC/PVA/ZnO nanocomposite films in various crucial optoelectronic applications.

Thermoluminescence Behavior and Kinetic Analysis of Quartz Under Gamma Irradiation

Aqshin Abishov, Sahib Mammadov, Muslim Gurbanov, Ahmad Ahadov, Aybeniz Ahadova — Sun, 08 Dec 2024 00:00:00 +0000

This study investigates the luminescence characteristics of quartz samples irradiated with a 60Co gamma source across a dose range of 57 to 570 Gy. Prior to irradiation, the samples were annealed at 650°C for two hours. The thermoluminescence (TL) spectra were measured at a heating rate of 5°C/sec, revealing two primary peaks at approximately 200°C and 320°C. The intermediate peak displayed a shoulder around 150°C. It was observed that the peak temperature maximum (Tm) at 206±2°C remained constant regardless of the irradiation dose. The intensity of the intermediate peak decreased significantly over time, with a lifetime estimated at 8±2 days for most doses and 19±2 days for the highest dose (570 Gy). Dose-response studies showed a linear relationship between the TL intensity and the irradiation dose up to 600 Gy. Comparisons with natural quartz samples indicated significant differences in glow curve shapes and sensitivities. Computerized glow curve deconvolution (CGCD) methods confirmed that the annealed quartz glow curve could be described as a superposition of four first-order kinetic peaks. These findings provide important insights into the stability and behavior of TL signals in quartz, which are crucial for applications in radiation dosimetry and archaeological dating.

Physical Mechanisms of Clear Air Turbulence

V.O. Lykhatskyi, V.I. Tkachenko, L.S. Bozbiei — Sun, 08 Dec 2024 00:00:00 +0000

Clear air turbulence (CAT) is a significant type of atmospheric turbulence that poses risks to aviation. Unlike other forms of turbulence, it occurs without substantial cloudiness, often under clear skies or with minimal cloud cover at the observation site. CAT can arise under various meteorological conditions, such as high atmospheric pressure, sunny weather, or in the presence of mountain ranges. Forecasting CAT is crucial for aviation safety, although its prediction is challenging due to its variability, sharp localization in the air flow, and variability in size and duration. Indirect signs can help predict CAT zones; however, direct observation is difficult, making it essential to develop forecasting methods and conduct research to ensure flight safety.

Interferometric Locating the Waist of a Laser Beam

Vyacheslav A. Maslov, Konstantin I. Muntean — Sun, 08 Dec 2024 00:00:00 +0000

An interferometric method for determining the location of a laser beam waist has been developed, which implements the dependence of the wavefront curvature on its distance to the waist. The initial laser beam, the waist location of which must be determined, is split by a shear interferometer into reference and information beams, which form a spatially non-localized interference field in reflected light. The period of the interference fringes observed in any cross-section of the interference field carries information about the location of the waist of the initial laser beam relative to this section. The distance from the waist to the plane of recording the period of the interference fringes is calculated using the formulas of Gaussian optics. The fundamental difference of this method from currently known ones allows for increasing the accuracy of the obtained result while simultaneously reducing the laboriousness of the measurement process.

Numerical Study on the Effects of Thermal and Mass Stratification on Chemically Reacting Unsteady MHD Nanofluid past an Oscillating Vertical Plate through a Porous Medium

Hemant Agarwal, Shyamanta Chakraborty, Rupam Shankar Nath — Sun, 08 Dec 2024 00:00:00 +0000

The purpose of this study is to study the combined influence of thermal and mass stratification on unsteady magnetohydrodynamic nanofluid past a vertically oscillating plate with variable temperature. The problem’s governing equations are numerically solved using the implicit Crank-Nicolson approach. Significant results from the thermal and mass stratification are contrasted with the environment where stratification is absent. The velocity decreases with both kinds of stratification, while the temperature decreases with thermal stratification and the concentration decreases with mass stratification. We use graphs to demonstrate the effects of the different parameters, including phase angle, thermal radiation, magnetic field strength, heat sources/sinks, and chemical reactions. Additionally, the Skin-Friction Coefficient, the Nusselt Number, and the Sherwood Number are computed and represented graphically. The findings highlight the critical role of stratification in improving fluid dynamics and increasing the efficiency of heat and mass transfer processes,
providing essential information for engineering and environmental applications under similar circumstances.

Influence of Electrophysical Parameters of Magnetodielectric Layer on a PCP on Its Electrodynamic Characteristics

Mikhail V. Nesterenko, Victor A. Katrich, Oleksandr M. Dumin, Natalya K. Blinova — Sun, 08 Dec 2024 00:00:00 +0000

Within the framework of the impedance concept, approximate analytical formulas for the distributed surface impedance of the magnetodielectric layer with the inhomogeneous permeability and permittivity located on a perfectly conducting plane (PCP) for the cases of a quadratic law of changes in electrical parameters along the layer thickness are obtained. A comparative analysis of electromagnetic waves reflection coefficient from this structure for various laws of change of the permeability and permittivity is presented.

Polyacrylamide’s Rheological and Physicochemical Properties: Analysis and Applications

Ummatjon A. Asrorov — Sun, 08 Dec 2024 00:00:00 +0000

This study presents an in-depth rheological characterization of polyacrylamide polymers produced locally, employing the Anton Paar MCR 92 (Modular Compact Rheometer). The polymer samples were systematically analyzed to understand their response to various external stimuli. Using infrared spectroscopy, the composition of the polymer was meticulously verified, ensuring a robust assessment of its molecular structure and chemical stability under different environmental conditions. Our findings elucidate the significant potential of polyacrylamide in diverse industrial applications, attributable to its adaptable viscoelastic properties and chemical resilience. The implications of this research are profound, suggesting enhanced utility of polyacrylamide in fields requiring precise material behavior modulation under dynamic conditions.

Studying the Effect of Transport Layers on ZrS2/MEH-PPV Solar Cells: Using SCAPS -1D Software

Sun, 08 Dec 2024 00:00:00 +0000

This study investigates the effect of charge transport layers on the efficiency of Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH_PPV) and Zirconium Disulfide (ZrS₂) solar cells using Scaps-1D software. It was found that by increasing the MEH-PPV thickness and decreasing its acceptor doping concentration, the efficiency (μ%), fill factor (FF), and short-circuit current density (J_sc) decreased. Conversely, increasing the thickness of the ZrS₂ electron transport layer and decreasing its donor doping density enhanced the efficiency (μ%) and short-circuit current density (J_sc) while maintaining a constant open-circuit voltage (V_oc). These results can be attributed to decreased charge separation and collection in MEH-PPV and reduced optical path length in ZrS₂. On the other hand, the back contact with work function is below 4.65 eV, the MEH-PPV/ZrS₂ solar cells produced the lowest efficiency compared to different types of back contact. Under optimal conditions, MEH-PPV/ZrS₂ solar cell shows a high efficiency of 21% when the dopant concentration of MEH-PPV and the value of the neutral defect density at the ZrS₂/ MEH-PPV interface are 10²²cm^-3 and 10⁹cm^-3respectively.

Effects of ZnS Buffer Layer on Performance of CIGS Solar Cell

Sun, 08 Dec 2024 00:00:00 +0000

Cu(In,Ga)Se₂ (CIGS)-based thin-film solar cells are currently among the most efficient. Zinc sulfide (ZnS) is the best buffer layer used in CIGS-based solar cells because it is non-toxic and has a wide band gap. In this study, we present a simulation of a CIGS solar cell with a ZnS buffer layer, carried out using the Silvaco-Atlas simulator. We attained an efficiency of 24.13%, short-circuit current of 37.81 mA/cm², an open circuit voltage of 740 mV and a fill factor of 78.78% at a bandgap around 1.41 eV, corresponding to an x ratio of 0.5. The photovoltaic performance of the ZnS/CIGS solar cell is improved by optimizing the effects of layer parameters such as thickness, acceptor and donor densities of the CIGS absorber and ZnS buffer layers. For a 0.035 μm thick ZnS acceptor with a density of 6 × 10¹⁷ cm^-3 and a 3 μm thick CIGS donor with a density of 10¹⁸ cm^-3, a maximum efficiency improved to 27.22%.

Structural Features of Reverse AOT Micelles in Water/Cyclohexane: Molecular Dynamics Study

Dilbar Bozorova, Shukur Gofurov, Mavlonbek Ziyaev, Oksana Ismailova — Sun, 08 Dec 2024 00:00:00 +0000

A study of the structural features of reverse micelles of Na AOT (sodium bis(2-ethylhexyl) sulfosuccinate) molecules in cyclohexane with an aqueous core was carried out using the molecular dynamics method. Reverse AOT micelles are formed in three-component systems containing a non-polar solvent, water, and AOT molecules at certain concentration ratios, expressed as w = [H₂O]/[AOT]. A strong hydrogen bond between water molecules and AOT was found at the concentration w=6. For the first time, a sharp decrease in hydrogen bonding between water molecules and AOT at w=7 was shown, caused by a difference in the packing of AOT molecules and the collective dynamics of water molecules in the micelle core. The calculated results are in good agreement with experimental data from other authors. It is shown that, along with the methods of vibrational spectroscopy and dynamic light scattering, the molecular dynamics method is also informative for determining the structural characteristics of supramolecular structures and analyzing the collective dynamics of water molecules.

The The Gas-Sensitive Properties of Tin Dioxide Films

Nuritdin Y. Yunusaliyev — Sun, 08 Dec 2024 00:00:00 +0000

This study investigates the fabrication and performance of SnO₂ thin films for gas sensing applications, utilizing a deposition method at 2 bar pressure and 8 ml/min flow rate. A multilayer structure was developed, comprising 14 layers, each with a thickness of 250 nm, optimized for sensitivity and stability. The gas sensor, featuring a film heater and sensitive elements doped with a 1% silicon additive, demonstrated a wide operational temperature range (20-370 °C). Characterization of resistance changes revealed significant hysteresis before isothermal annealing, with resistance values stabilizing after prolonged exposure to 370 °C. Post-annealing, the sensor exhibited three orders of magnitude higher resistance, indicating improved stability and electronic transport properties. Doping with a 1N AgNO₃ solution significantly enhanced sensitivity to ammonia, with a detection threshold of 500 ppm, while sensitivity to alcohol vapors decreased, indicating selectivity. Experimental results confirm that local doping and thermal treatment effectively enhance the metrological characteristics of SnO₂-based sensors, making them suitable for detecting toxic gases.

Investigation of Volt-Ampere Characteristics of a Gas Sensitive Sensor Based on Tin Dioxide

Sun, 08 Dec 2024 00:00:00 +0000

The volt-ampere characteristics of the sensitive elements of gas sensors are investigated and plotted in coordinates corresponding to various mechanisms of the transfer current. It has been established that the prevailing mechanism of current transfer in the section from 0 to 6 V is Om’s law, in the interval (3 - 6) V the Mott’s law is fulfilled, and at higher voltages deviations from these laws are observed. It is determined that the laws of Om and Mot confirm the mechanism of the flow of currents limited by the space charge.

Computational Study of Drug Delivery Systems with Radionuclide and Fluorescence Imaging Modalities. I. Albumin-Based Systems for Doxorubicin Delivery

Sun, 08 Dec 2024 00:00:00 +0000

Molecular docking and molecular dynamics methodologies were employed to design and evaluate delivery systems for the antineoplastic agent doxorubicin (DOX) utilizing human serum albumin (HSA) as the carrier. To engineer a drug delivery system (DDS) with dual imaging modalities, complexes of the radionuclide technetium-99m (TCC) and near-infrared (NIR) fluorescent dyes, including indocyanine green (IG), methylene blue (MB), heptamethine cyanine dye AK7-5, and squaraine dye SQ1, were integrated into the protein nanocarriers. The highest binding affinities to the proteins were identified for TCC [^99mTc]Tc-diisopropyl iminodiacetic acid (TcDIS), [^99mTc]Tc-hydrazinonicotinic acid-H6F (TcHYN), [^99mTc]Tc-Mebrofenin (TcMEB), as well as the fluorescent dyes IG and SQ1. Molecular docking analyses revealed that most technetium complexes (TCCs) bind to HSA domain I, with some exceptions showing affinity for domains I and III or domain III alone. Ternary and quaternary protein-ligand systems were explored using multiple ligand docking approaches. In ternary systems, DOX binding sites were identified either in domain I or in a region spanning multiple domains, depending on potential overlap with TCC binding sites. For quaternary systems incorporating NIR fluorophores, binding affinities decreased in the order: IG > SQ1 > AK7-5 > MB. Molecular dynamics simulations of HSA-DOX-MB and HSA-DOX-IG complexes demonstrated stable associations between the components, with consistent center-of-mass distances and minimal perturbation of HSA structure. These findings support the potential of HSA as a suitable carrier for developing dual-modality imaging nanocarriers incorporating both radionuclide and fluorescence imaging capabilities.

Polyphenol-Mediated Modulation of Amyloid-Lipid Interactions

U. Tarabara, V. Trusova, M.H. Thomsen, G. Gorbenko — Sun, 08 Dec 2024 00:00:00 +0000

Förster resonance energy transfer (FRET) between the membrane fluorescent probes pyrene and TDV was employed to investigate the modulation of amyloid-lipid interactions by polyphenols. The effects of various polyphenols, including quercetin, curcumin, gallic and salicylic acids, on the complexation between the amyloid fibrils derived from N-terminal fragment of apolipoprotein A-I (ApoA-IF) and insulin (InsF), and liposomes composed of phosphatidylcholine (PC) and its mixtures with cardiolipin (CL), cholesterol (Chol), or phosphatidylglycerol (PG) were investigated. The incorporation of polyphenols resulted in decreased energy transfer efficiency, indicating a significant alteration in the spatial relationship between amyloid fibrils and lipid membranes. The magnitude of this effect was found to be dependent on lipid bilayer composition, the chemical nature of the polyphenols, and the type of amyloidogenic protein. Notably, curcumin exhibited the most pronounced impact across all systems, with a particularly strong effect on ApoA-IF compared to InsF. This differential response suggests protein-specific mechanisms of interaction and highlights the potential for targeted therapeutic approaches. Our findings provide novel insights into the intricate interplay between polyphenols, amyloid fibrils, and lipid membranes, contributing to the fundamental understanding of amyloid-related pathologies and opening new avenues for the development of polyphenol-based therapeutic strategies in amyloid-associated disorders.

To the Theory of Intraband Single-Photon Absorption of Light in Semiconductors with Zinc-Blende Structure

Rustam Y. Rasulov, Voxob R. Rasulov, Forrukh U. Kasimov, Makhliyo A. Mamatova — Sun, 08 Dec 2024 00:00:00 +0000

A theoretical analysis of the frequency-temperature dependence of the coefficient of single-photon absorption of polarized radiation in narrow- and wide-bandgap semiconductors has been conducted, considering intraband optical transitions and the temperature dependence of band parameters. It has been shown that with a fixed frequency, the single-photon absorption coefficient initially increases with temperature, reaches a maximum, and then decreases. The maximum value shifts towards lower frequencies for both narrow- and wide-bandgap semiconductors when considering the temperature dependence of the bandgap width and the effective mass of holes. It was determined that in semiconductors with a zinc-blende lattice structure, the consideration of the temperature dependence of the band parameters leads to a decrease in the amplitude value of the frequency and temperature dependence of the single-photon absorption coefficient. As the temperature increases, the absorption threshold decreases, which is noticeably observed when taking into account the Passler formula. Each type of optical transition contributes differently to the frequency, temperature, and polarization dependencies of K⁽¹⁾_SO,lh(ω,T).

Enhancement of Molecular Structural and Linear/Nonlinear Optical Features of Chitosan/Titanium Dioxide Nanocomposite Films for Food Packaging and Optoelectronic Applications

Osiris Guirguis, Najlaa D. Alharbi — Sun, 08 Dec 2024 00:00:00 +0000

The current study aims to synthesize and characterize nanocomposite films of chitosan and titanium dioxide in terms of molecular structure, thermal and optical properties for use in food packaging and optoelectronic applications. The Fourier-transform infrared (FTIR) spectroscopy was used to study the interaction between the TiO₂-NPs and chitosan and the analysis confirmed that TiO₂-NPs interacted with chitosan and demonstrated good compatibility. Differential scanning calorimetry and thermogravimetric analysis revealed that increasing the concentration of TiO₂-NPs improved the thermal stability of the nanocomposites. The linear optical properties in the UV-Vis range (200–800 nm) were measured spectrophotometrically. Below 400 nm, the transmittance spectra of the nanocomposites show decreased degrees of transparency, indicating their capacity to entirely block UV-light transmission. Tauc's model was used to identify the types of electronic transitions in the samples. The single-oscillator model was utilized to investigate the dispersion energy and parameters. Nonlinear optical properties were also investigated. UV-Vis in the region (360-410 nm), the analysis revealed that increasing the concentration of TiO₂-NPs from 0 to 12 wt% reduced the absorption edge from 2.716 to 2.043 eV, decreased the direct (3.282 to 2.798 eV) and indirect (2.417 to 1.581 eV) energy band gaps, increased the Urbach energy from 0.692 to 1.295 eV, decreased the dispersion energy from 11.324 to 5.621 eV, decreased the single oscillator energy from 6.308 to 5.393 eV, and improved the other linear and nonlinear parameters. The findings support the usage of CS/TiO₂ nanocomposite films in the packaging industry and a variety of optical applications.

First-Principles Study: The Optoelectronic Properties of the Wurtzite Alloy InGaN Based Solar Cells, within Modified Becke-Johnson (mBJ) Exchange Potential

Thu, 28 Nov 2024 20:43:52 +0000

Numerical simulation based on Full Potential-Linerazed Augmented Plane Wave calculations (FP-LAPW) is implemented in WIEN2K code to study the fundamental structural and optoelectronic properties of the Wurtzite ternary alloy structure InxGa1-xN (x = 0.125, 0.375, 0.625 and 0.875) matched on GaN substrate using a 16-atom supercell. The generalized gradient approximation of Wu and Cohen, the standard local density approach, and the Tran-Blaha modified Becke–Johnson potential were applied to improve the band structure and optical properties of the concerning compounds. Whenever conceivable, we compare the obtained results by experiments and computations performed with diverse computational schemes. In those alloys, the essential points in the optical spectra display the passage of electrons from the valance band to the unoccupied states in the conduction band. The results lead that Becke–Johnson potential will be a promising potential for the bandgaps engineering of III-V compounds which supplied that those materials had crucial absorption coefficients that lead to the application for optoelectronics components, especially solar cells.

Mass Transfer and MHD Free Convection Flow Across a Stretching Sheet with a Heat Source and Chemical Reaction

Sunmoni Mudoi, Satyabhushan Roy, Dipak Sarma, Ankur Kumar Sarma — Sun, 08 Dec 2024 00:00:00 +0000

This work examines mass transfer and MHD free convective flow across a stretching sheet in the presence of a heat source and a chemical reaction. The sheet's stretching action propels the flow, while a magnetic field applied perpendicular to the flow direction influences it. The effects of gradients in temperature and concentration on buoyant forces are also taken into account. The continuity, momentum, energy, and concentration equations are among the coupled nonlinear partial differential equations that regulate the system. Similarity transformations are used to convert these equations into a system of ordinary differential equations, which are then numerically solved using bvp4c techniques. In this investigation, magnetic, buoyancy, chemical reaction rate, and heat source factors are the main parameters of interest. The outcomes show the influence of these parameters on the boundary layer's temperature, concentration, and velocity profiles. To quantify the mass transfer rate, heat transfer rate, and shear stress at the sheet surface, the skin friction coefficient, Nusselt number, and Sherwood number are calculated. By manipulating the magnetic field, chemical reactions, and heat generation, the work offers important new insights into how to best utilise MHD flows in industrial processes, such as polymer manufacturing, chemical reactors, and cooling systems.

Interaction of Heavy Metals with β-Lactoglobulin: Molecular Dynamics Study

O. Zhytniakivska, U. Tarabara, K. Vus, V. Trusova, G. Gorbenko — Sun, 08 Dec 2024 00:00:00 +0000

β-Lactoglobulin (β-lg), the predominant whey protein, is renowned for its nutritional and functional attributes, including its ability to bind hydrophobic and charged molecules. These properties make β-lg a promising candidate for applications such as drug delivery systems, nutraceutical carriers, and nanocomposites for environmental remediation, particularly in detecting and removing heavy metals. Despite its potential, the impact of heavy metal binding on β-lg's structure and stability remains insufficiently explored, posing challenges for its advanced applications. In this study, molecular dynamics (MD) simulations were employed to investigate the structural and dynamic responses of β-lg to the binding of heavy metal ions—Cd²⁺, Ni²⁺, Co³⁺, Pb²⁺, and Pt²⁺. A series of 200-ns MD simulations for the metal-protein complexes was conducted at 300 K using GROMACS software and the CHARMM General Force Field. Key structural parameters analyzed included backbone root-mean-square deviation (RMSD), radius of gyration (Rg), solvent-accessible surface area (SASA), and root-mean-square fluctuations (RMSF). The results demonstrated that binding of Cd²⁺, Ni²⁺, Co³⁺, Pb²⁺, and Pt²⁺ destabilized the protein's structure, with notable effects observed in critical regions such as the EF loop, H-strand, and AB loop. The extent of destabilization varied depending on the specific heavy metal ion. These findings emphasize the need for detailed residue-level analyses to fully elucidate the structural changes induced by metal binding and their implications for β-lg's functional properties. This work provides valuable insights into the behavior of β-lg under heavy metal binding and lays the groundwork for developing β-lg-based nanosystems for environmental and biomedical applications.

The Formation of Ion-Acoustic Solitary Waves in a Plasma Having Nonextensive Electrons and Positrons

Rafia Khanam, Satyendra Nath Barman — Sun, 08 Dec 2024 00:00:00 +0000

In this plasma model, consisting of ions, electrons and positrons have been theoretically investigated when both the electrons and positrons are obeying q-nonextensive velocity distribution. The reductive perturbation method is used to obtain a Korteweg-de Vries(KdV) equation describing the basic set of normalized fluid equations. The ion-acoustic solitary waves model are depended on nonextensive parameter, electron to positron temperature ratio, ion to electron temperature ratio and streaming velocity are investigated numerically. It has been found that solely fast ion-acoustic modes can produce the coexistence of small amplitude rarefactive solitons.

Generalized Ghost Pilgrim Dark Energy in Brans–Dicke Theory

Yetchena Prasanthi, Neelima Davuluri — Sun, 08 Dec 2024 00:00:00 +0000

This paper aims to investigate, how the Bianchi Type-V cosmological model can be solved using the generalized ghost pilgrim dark energy postulated by the Brans-Dicke theory of gravitation (Phys. Rev.124, 925 1961). To discover the answers, we rely on the assumptions of (i) the correlation between metric potentials and (ii) the exponential relationship between scale factor and scalar field. The generalized ghost pilgrim dark energy model has been found to be correlated with the polytrophic gas dark energy model. A few physical quantities have been used to explain the solutions' physical behavior.

Finite Element Analysis of a Dynamic Linear Crack Problem

Sun, 08 Dec 2024 00:00:00 +0000

This work investigates the problem of a linear crack in the middle of a uniform elastic medium under normal tension-compression loading. The direct Finite Element numerical procedure is used to solve the fractured media deformation problem, which also includes an examination of the dynamic field variables of the problem. A Finite Element algorithm that satisfies the unilateral Signorini contact constraint is also described for solving the crack faces' contact interaction, as well as how this affects the qualitative and quantitative numerical results while calculating the dynamic fracture parameter.