<abstract><title style='display:none'>Abstract</title>Fluorides-based perovskites are currently the typical materials being used in spintronic devices, optoelectronic and magneto-resistance colossal fields. Solar cells made of Fluoro-perovskite hold much promise for the future of solar energy. The electronic structure and magnetic properties of KFeF3, KCoF3 and KNiF3 Fluorides are studied using ab initio Calculation. We have analysed the structural phases, total and partial electronic densities and band structures within the (DFT) vs the DFT+U description. We show the Electro-Magnetic Behavior using L(S)DA+U vs L(S)DA in a comparative study of cation effect by integrating three types of crystal structures (Cubic (Pm-3m), Four-Layered Hexagonal (P6/mmc), and Orthorhombic (Pnma)). Equilibrium lattices agree very well with experimental and theoretical data. Magnetic moment of each phase is discussed. The obtained results confirmed that the three crystal structures invested here exhibit Ferromagnetic (FM) behavior. The introduction of the Hubbard’s parameter U increases lattice parameters and magnetic moment. We deduce that the second cation plays an important role in the magnetic effects. L(S)DA+U show correctly that KFeF3, KCoF3 and KNiF3 are insulators.</abstract>

Electro-Magnetic Behavior of Highly Correlated Fluorides KFeF3, KCoF3 and KNiF3: A Comparative <italic>Ab-initio</italic> Study of Cation Effect

<abstract>
<title style='display:none'>Abstract</title>
In this work, an ab-initio calculation is used to investigate the elastic constants and some other mechanical and thermal parameters of tetragonal Cu2ZnSnS4 (CZTS) quaternary semiconducting bulk material in Kesterite (KS) and Stannite (ST) phases. The Quantum Espresso code within the Ultra Soft pseudo potentials (USPP) and the local density approximation (LDA) approach were used in the calculation. Firstly,, studies are started with the prediction of the elastic stiffness constants <italic>Cij</italic> and the normal and shear anisotropy factors. Then some other mechanical moduli, especially the isotropic bulk modulus <italic>B</italic>, the shear modulus <italic>G</italic>, the Young modulus <italic>E</italic>, the Poisson’s ratio <italic>ν</italic>, and the Pugh’s criteria (<italic>G</italic>/<italic>B</italic>) are delivered. The analysis of the mechanical stability criteria at equilibrium shows that our elastic stiffness constants <italic>Cij </italic>of CZTS material obey all the stability conditions. Additionally, some other parameters of the CZTS semiconductor, especially: the Vickers hardness <italic>HV</italic>, the sound velocity, the Debye temperature <italic>θD</italic> and the melting temperature <italic>Tm </italic>were also calculated. The obtained values of the elastic constants <italic>Cij</italic> and other mechanical and thermal parameters agree well with experimental and other theoretical results of the literature. The Debye temperature <italic>θD</italic> of the KS phase was found at around 332.7 K, and that of the stannite phase was found equal to 329.1 K, respectively.
</abstract>

Elastic Constants of Tetragonal Cu2ZnSnS4 Semiconductor: AB-Initio Calculation

<abstract><title style='display:none'>Abstract</title>In this paper, we performed a first principle study for new half-Heusler LiSrX(X= N, P, and As) working with WIEN2k code in the frame work of the density functional theory, and the Boltzmann theory. We estimated the exchange-correlation potential by the generalized gradient approximation (GGA). Energetically, the three compounds show a high stability in structure type2, we notice that the lattice constant increased while bulk modulus decreased in replacing the ions of size increasing. Based on our calculations, LiSrN, LiSrP, and LiSrAs compounds are mechanically stable, and show semiconductor nature with indirect band gaps of 1.21, 1.75 for LiSrN and LiSrAs, and direct band gap of 1.94 eV for LiSrP. The thermoelectric properties are calculated for LiSrX (X=N, P, and As) and they found a high power factor for the p-type doping concentration.</abstract>

Electronic and Thermoelectric Properties in Li-Based Half-Heusler Compounds: A First Principle Study

<abstract>
<title style='display:none'>Abstract</title>
The present work aims to investigate the structural and thermodynamic properties of homogenous tetragonal Cu2ZnSnS4 (CZTS) absorber material in Kesterite phase using first-principle calculations based on density functional theory (DFT). This approach requires only knowledge of the atomic species and crystal structure to predict several physical properties of materials. The Quantum Espresso code within the Ultra Soft pseudopotentials (USPP) and the local density approximation (LDA) were used in the calculations. Equilibrium unit cell volumes, bulk modulus, as well as the pressure derivative of the bulk modulus are predicted. In addition, several thermodynamic properties, especially: the Debye’s vibrational energy, the vibrational free energy, the vibrational entropy, and the constant volume heat capacity at different temperatures <italic>T</italic> of Cu2ZnSnS4 material are calculated and discussed. Our study shows that the vibrational energy, the entropy and the constant volume heat capacity increase with increasing temperature, while the vibrational free energy decreases monotonously with the increase of temperature.
</abstract>

Structural and Thermodynamic Properties oF Cu2ZnSnS4 Material: Theoretical Prediction

<abstract><title style='display:none'>Abstract</title>Ab initio calculations of BiFeO3 magnetic perovskite are carried. Accurate density functional theory calculations were performed considering a U-Hubbard correction (DFT+U) to account for on-site Coulomb interactions of the 3d-Fe states. We have applied the Full-potential linearized augmented plane waves (FP-LAPW) method. Exchange-correlation effects are treated using the Local Spin Density approximation (L(S)DA+U) vs generalized gradient approximations (GGA+U). Equilibrium lattices agree very well with other theoretical and experimental data. The magnetization energy differences between Spin Up and Spin Dn states are small. Spin effect and magnetic moment obtained from subsequent (L(S)DA+U) and (GGA+U) calculations are also discussed in different magnetic configurations: The Ferromagnetic cubic phase (Pm-3m), The A-type Antiferromagnetic (P4/mmc) and The G-type Antiferromagnetic (Fm-3m). The nature of magnetism arises mainly from the Fe-site exhibiting a G-type antiferromagnetic ordering. The electronic structure shows that BiFeO3 has a metallic band gap. This multiferroic exhibit strong hybridization of the 3d-Fe and 2p-O orbitals. Therefore, the Multiferroic BiFeO3 perovskite has driven significant research interest due to their promising technological potential. It’s a good candidate for potential applications in spintronic, and to aid the development of the next generation of data storage and multi-functional technological devices.</abstract>

Structural Stability and Magnetic Ordering in BiFeO3 Perovskite Oxide: A Comparative Study GGA+U vs L(S)DA+U

<abstract><title style='display:none'>Abstract</title>Simulate the behavior of a quarter car suspension system with Simulink®. Consider only vertical movement of the car, neglecting roll and pitch. All movements of the car axes are modeled as having equal amplitude. The characteristic equations that describe the behavior of dynamical systems based on FBD (Free Body Diagram) of automotive suspension. We make the simulation model in six steps. In simulation we consider the damping coefficient, <italic>c</italic>, variable. The rest of parameters are constant (mass, speed and stiffness). The simulation parametrs are defined in Mathlab®. We follow the final signal created on the oscilloscope. At the end of the study, we concluded the effect of damping coefficient changes over the comfort.</abstract>

Quarter Car Suspension System With One Degree Of Freedom Simulated Using Simulink

<abstract>
<title style='display:none'>Abstract</title>
The estimation of solar irradiance under clear sky conditions is still a research topic. Many times, accessible empirical models are applied in practice, even if more uncertainty is expected than in the case of complex models. This paper reports a class of innovative empirical models for estimating clear sky global solar irradiance. Although the models are of an empirical nature, the mathematical equations are inspired by the physics behind the radiative transfer in the atmosphere. The models are developed with high-quality data recorded on the Solar Platform of the West University of Timisoara, Romania. Considering the local character of the empirical models, the development process is described in detail so that it can be replicated in other locations. Having only deterministic quantities as input, the proposed models harmoniously combine the two key requirements for practical applications: accessibility and accuracy.
</abstract>

A Physically Inspired Model for Estimating Clear-Sky Solar Irradiance

<abstract>
<title style='display:none'>Abstract</title>
In this research, the effect copper on the structural, morphological, optical, and electrical properties of nickel oxide thin films was studied at different copper concentrations. Thin transparent films of nickel oxide (NiO) doped with copper (Cu) were deposited on glass substrates at a temperature of 400 °C using the spray pyrolysis technique. The structural study showed that all the prepared polycrystalline films had a cubic structure with a preferential orientation along (111). Copper was well integrated into the host lattice without changing the structure. SEM images showed that the films were well adhered with a wrinkled network structure. The optical band gap ranges from 3.70 eV to 3.50 eV, and the Urbach energy, which ranges from 0.34 eV to 0.5 eV, has also been discussed. The highest conductivity value of 6.23 × 10⁻³ (Ω·cm)⁻¹ was found at a copper concentration of 2 %.
</abstract>

Synthesis and Characterization of Un-Doped and Copper Doped Nickel Oxide Thin Films

<abstract>
<title style='display:none'>Abstract</title>
In double-skin facades, airflow is mainly induced by buoyancy forces due to temperature gradients and air compressibility. In practice, this passive system is also affected by ambient crosswind. The present work is focused on the analysis of the aerothermal behavior of an asymmetrically heated channel interacting with a transverse airflow. To achieve this, we utilized the computational fluid dynamics (CFD) technique based on the finite volume method to predict the system’s performance. After validating the adopted numerical model, we examined the flow structure for different channel widths, and we determined the corresponding ventilation flow rates. We integrated the effect of wind with the thermosiphon effect. The thermo-aerodynamic performance of the facade was presented as a function of wind velocities, which significantly influence the airflow through the cavity and its openings.
</abstract>

Effects of Crosswinds on the Aerothermal Behaviour of a Double-Skin Façade

<abstract>
<title style='display:none'>Abstract</title>
This paper reports a novel prototype of heterojunction solar cells based on semiconductor/perovskite structure using the solar cell capacitance one-dimensional simulator (SCAPS 1D). The device schematic consists of Glass/ITO/ETL/MASnBr3/CZTGS/HTL layers with perovskite i-MASnBr3 as the permeable layer. The thickness of the absorber layer, carrier charge concentration, and the effect of temperature and series resistances are optimized. The research examines several critical parameters essential for solar cell performance, including a power conversion efficiency PCE of 50%, an open-circuit voltage Voc of 1.62 V, a fill factor FF of 91.5%, and a short-circuit current density Jsc of -34.06 mA/cm2. The temperature and series resistance effects, as well as quantum efficiency QE, and J-V curve simulations with varying acceptor density, are investigated.
</abstract>

I-MASnBr3 /CZTGS Heterojunction Solar Cell Layer Optimization Investigated Using Scaps-1D Software Exhibited Excellent Performance at 50 %

<abstract>
<title style='display:none'>Abstract</title>
In this paper, a numerical study is conducted to investigate the effect of using Phase Change Materials (PCMs) in building bricks to improve the thermal inertia of buildings in hot and dry regions. A numerical model is developed to simulate the heat transfer in a brick with cylindrical holes filled with PCM. The effects of the number, type, and arrangement of PCMs on the thermal performance of the brick are investigated. The results show that the use of PCMs can significantly reduce the heat flux through the brick. The optimal number of PCMs is found to be three layers. The optimal type of PCM for the first layer is n-Eicosane, for the second layer is Paraffin Wax, and for the third layer is n-Octadecane. The enhanced brick configuration, with specific PCM arrangements, reduced total heat flux by up to 71.53% in the simulation period, compared to a brick without PCM.
</abstract>

Enhancing Building Thermal Inertia: Impact of Surface-to-Volume Ratio on Multi-Layered PCM-Integrated Brick Walls

<abstract>
<title style='display:none'>Abstract</title>
Thin films of cobalt sulfide were grown on glass substrates at four different temperatures (250 °C, 300 °C, 350 °C and 400 °C) using spray-pyrolysis technique. The precursor solutions were prepared using cobalt chloride and thiourea. The effect of deposition temperature on the structural, morphological, and optical properties of cobalt sulfide thin films was investigated using different experimental techniques such as X-ray diffraction (XRD), and UV-visible spectrophotometry, Fourier Transform Infrared Spectroscopy (FT-IR) and four-probe method. The XRD analysis showed that crystallite size varies from 9.76 to 14.11 nm with increasing the deposition temperature. UV-visible data analysis shows a decrease in the band gap energies with increasing temperature (1.82 eV for 250 °C, 1.76 eV for 300 °C, 1.72 eV for 350 °C, and 1.65 eV for 400 °C). The analysis of the chemical composition by FTIR confirmed the presence of Co, S elements. On the other hand, the electrical conductivity of the cobalt sulfide thin films increased owing to the increase in the crystallite size and reduction of defects density.
</abstract>

Substrate Temperature Effect on the Structural, Optical and Morphological Proprties of Cobalt Sulfide Thin Films Deposited Using Spray Pyrolisis

<abstract>
<title style='display:none'>Abstract</title>
Recently, the lead-free double perovskite compounds have been evinced to be promising candidate for thermoelectric and optoelectronic technologies. In this paper; we have probed a theoretical works on the different physical properties: Structural, electronic, elastic, optical and thermoelectrical properties of the chalcogenide double perovskites A2GaNbS6 (A=Ca, Sr and Ba) within the instructions of density functional theory. The calculations have incorporated using the full potential linearized augmented plane waves (FP-LAPW) method within gradient generalized approximation (GGA) and the modified Becke-Johnson potential (mBJ) to describe the exchange-correlation potential as embodied in the WIEN2K code. The computed structural results show that the non-magnetic structure state is energetically the most stable structure in the cubic <italic>Fm3̄m</italic> (225) configuration, also the elastic and mechanical properties indicate that A2GaNbS6 (A=Ca, Sr and Ba) have a ductile nature. According to the electronic plots the three compounds have a semiconducting behavior with indirect (pseudo-direct) band gap of 1.21, 1.28 and 1.32 eV. Important optical responses of studied chalcogenide double perovskites are found in the visible and ultraviolet energy ranges. Finally, the thermoelectric effectiveness of the three compounds have been probed by computing parameters like Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit with semi-classical Boltzmann theory and constant relaxation time approximation as implemented in BoltzTrap code, the obtained results show that the chalcogenide double perovskites could be a good candidate for thermoelectric applications.
</abstract>

Structural, Electronic, Elastic, Mechanical, Optical and Thermoelectric Properties of the Chalcogenide Double Perovskites A2GaNbS6 (A = Ca, Sr and Ba): Insights From Density Functional Theory Calculations

<abstract><title style='display:none'>Abstract</title> We consider an application of the tetrad formalism introduced by Cardall et al. [Phys. Rev. D 88 (2013) 023011] to the problem of a rigidly rotating relativistic gas in thermal equilibrium and discuss the possible applications of this formalism to rel- ativistic lattice Boltzmann simulations. We present in detail the transformation to the comoving frame, the choice of tetrad, as well as the explicit calculation and analysis of the components of the equilibrium particle ow four-vector and of the equilibrium stress-energy tensor.</abstract>

Relativistic Rotating Boltzmann Gas Using the Tetrad Formalism

<abstract>
<title style='display:none'>Abstract</title>
The present work aims to predict the elastic constants and other significant properties of ordered BxAl1-xSb (0 ≤ x ≤ 1) ternary semiconducting alloys. We report the initial results of the elastic stiffness constants, the bulk modulus, the aggregate shear modulus, the Cauchy ratio, the aggregate Young’s modulus, the Born ratio, the isotropy factor, the fracture toughness and the longitudinal, transverse and average sound velocities. The Debye temperature and the melting point were also predicted using two different empirical expressions. Except the Cauchy ratio, which decreases with enhancing boron content x, all other physical quantities of BxAl1-xSb alloys increase gradually and monotonically with increasing of boron concentration x in the range 0-1.
Our obtained data for BSb and AlSb binary semiconducting compounds are discussed and analyzed in comparison with experimental and other theoretical values of the literature. Generally, our data for BSb and AlSb are in good agreement with other results reported previously in literature. Indeed, our obtained value (335.82 K) of the Debye temperature for AlSb compound overestimates the result (328.6 K) reported by Salehi et al. by around 2.03%, while that (1520 K) of the melting point for BSb overestimates the result (1500 K) reported recently by Bioud et al. by around 1.34%. Furthermore, to the best of our knowledge, no theoretical or experimental data were reported in the literature on the elastic constants and other properties for BxAl1-xSb alloys to compare with them.
</abstract>

Theoretical Prediction of Mechanical Properties of BxAl1−xSb Ternary Semiconducting Alloys

<abstract><title style='display:none'>Abstract</title>An investigation of silicon-based tandem solar cells incorporating Al-doped ZnO (AZO) and Cu2O metal oxides, via two of the most efficient methods of optical modeling, specifically ray tracing and transfer matrix algorithms, was performed. The simulations were conducted based on specialized software, namely Silvaco Atlas and MATLAB, as well as on OPAL2 simulation platform. The optical analysis involved the calculation of the spectral curves for reflectance, absorptance and transmittance for different thicknesses of the thin film layers constituting the cell. It was established the optimum thickness of the AZO layer based on the minimum reflectance and maximum transmittance. Moreover, several materials were investigated in order to determine the optimum buffer layer for the tandem solar cell, based on optical modeling. The optical parameters of the ZnO/Cu2O top subcell were optimized, in order to achieve the highest conversion efficiency of such heterojunction solar cell.</abstract>

Optical Modeling and Simulation of Tandem Metal Oxide Solar Cells

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Annals of West University of Timisoara - Physics

 The first issue of the Annals of the West University of Timisoara, was published in 1963 under the name of Mathematical and Physical Sciences Series, and it was issued on yearly...

 The first issue of the Annals of the West University of Timisoara, was published in 1963 under the name of Mathematical and Physical...

Annals of West University of Timisoara - Physics

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