scholarly journals Structure and Properties of ZnSnP2 With the Application in Photovoltaic Devices by Using CdS and ZnTe Buffer Layers

2021 ◽  
Keyword(s):  
Solar Cell ◽  
Density Functional ◽  
Empirical Relation ◽  
Harmonic Approximation ◽  
The Body ◽  
Buffer Layers ◽  
Maximum Efficiency ◽  
The Density Functional Theory ◽  
And Performance ◽  
Semi Empirical

Ab initio calculations have been performed by the linearized augmented plane wave (LAPW) method as implemented in the WIEN2K code within the density functional theory to obtain the structural, electronic and optical properties of ZnSnP2 in the body centered tetragonal (BCT) phase. The six elastic constants (C11, C12, C13, C33, C44 and C66) and mechanical parameters have been presented and compared with the available experimental data. The thermodynamic calculations within the quasi-harmonic approximation is used to give an accurate description of the pressure-temperature dependence of the thermal-expansion coefficient, bulk modulus, specific heat, Debye temperature, entropy Grüneisen parameters. Based on the semi-empirical relation, we have determined the hardness of the material; which attributed to different covalent bonding strengths. Further, ZnSnP2 solar cell devices have been modeled; device physics and performance parameters have analyzed for ZnTe and CdS buffer layers. Simulation results for ZnSnP2 thin layer solar cell show the maximum efficiency (22.9%) with ZnTe as the buffer layer. Most of the investigated parameters are reported for the first time.

scholarly journals Fundamental Materialistic Properties of ZnSnP2 for Solar Energy Conversion and Environmental Friendly Photovoltaic Devices

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Solar Cell ◽  
Density Functional ◽  
Empirical Relation ◽  
Harmonic Approximation ◽  
The Body ◽  
Buffer Layers ◽  
Maximum Efficiency ◽  
Full Potential ◽  
And Performance ◽  
Semi Empirical

Ab initio calculations have been performed by the full potential linearized augmented plane wave (FP-LAPW) method as implemented in the WIEN2K code within the density functional theory to obtain the fundamental physical properties of ZnSnP2 in the body centered tetragonal (BCT) phase. The six elastic constants (C11, C12, C13, C33, C44 and C66) and mechanical parameters have been presented and compared with the available experimental data. The thermal properties within the quasi-harmonic approximation is used to give an accurate description of the pressure-temperature dependence of the thermal-expansion coefficient, bulk modulus, specific heat, Debye temperature, entropy Grüneisen parameters. Based on the semi-empirical relation, we have determined the hardness of the material; which attributed to different covalent bonding strengths. Further, ZnSnP2 solar cell devices have been modeled; device physics and performance parameters have analyzed for ZnTe and CdS buffer layers. Simulation results for ZnSnP2 thin layer solar cell show the maximum efficiency (22.9%) with ZnTe as the buffer layer. Most of the investigated parameters are reported for the first time.

scholarly journals Oxygen and silicon β-factors of zircon estimated from first principles

2019 ◽  
Vol 27 (4) ◽  
pp. 420-430
Author(s):  
D. P. Krylov
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Isotope Fractionation ◽  
Isotopic Equilibrium ◽  
Functional Theory ◽  
Empirical Calibration ◽  
The Density Functional Theory ◽  
Cubic Polynomials ◽  
Semi Empirical ◽  
Fractionation Factors

Zircon β-factors have been calibrated against temperature for isotopic substitutions of 18O/16O and 30Si/28Si. Calculations were performed using the density functional theory (DFT) with the “frozen phonon” approach. The deduced geometric parameters of the zircon unit cell, and the phonon frequencies calculated, agree well with the experimental data. The results are expressed by the cubic polynomials on x = 106/T(K)2: 1000lnβzrn(18O/16O) = 9.83055x – 0.19499x2 + 0.00388x3;  1000lnβzrn(30Si/28Si) = 7.89907x – 0.17978x2 + 0.00377x3. The expressions deduced can be utilized to construct geothermometers if combined with β-factors of coexisting phases. New calibrations of quartz-zircon are given. The new values of 1000lnβzrn and the estimated isotope fractionation factors between quartz and zircon (1000lnβqtz–1000lnβzrn) deviate considerably from previously used experimental, empirical, and semi-empirical calibration of the isotopic equilibrium.

Pressure effect on the structural, phonon, elastic and thermodynamic properties of L12phase RH3TA: First-principles calculations

2018 ◽  
Vol 32 (14) ◽  
pp. 1850169
Author(s):  
Leini Wang ◽  
Zhang Jian ◽  
Wei Ning
Keyword(s):  
Thermodynamic Properties ◽  
Density Functional ◽  
Harmonic Approximation ◽  
Debye Model ◽  
Approximation Model ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Relationship Of ◽  
G Ratio ◽  
Wide Pressure

The phonon, elastic and thermodynamic properties of L12phase Rh3Ta have been investigated by the density functional theory (DFT) approach combined with the quasi-harmonic approximation model. The results of the phonon band structure show that L12phase Rh3Ta possesses dynamical stability in the pressure range from 0–80 GPa due to the absence of imaginary frequencies. The pressure dependences with the elastic constants C[Formula: see text], shear modulus G, bulk modulus B, Young’s modulus Y, Poisson’s ratio and B/G ratio have been analyzed. The results of the elastic properties studies show that L12phase Rh3Ta compound is mechanically stable and possesses a higher hardness, improved ductility and plasticity under higher pressures. The pressure and temperature relationship of the thermodynamic properties, such as the Debye temperature [Formula: see text], heat capacity C[Formula: see text], thermal expansion coefficient [Formula: see text] and the Grüneisen parameter [Formula: see text] are predicted by the quasi-harmonic Debye model in a wide pressure (0–80 GPa) and temperature (0–750 K) ranges.

scholarly journals Evaluation of Effectiveness of Waterjet Propulsor for a Small Underwater Vehicle

2021 ◽  
Vol 28 (4) ◽  
pp. 30-41
Author(s):  
Lech Rowinski ◽  
Maciej Kaczmarczyk
Keyword(s):  
Small Diameter ◽  
Mechanical Damage ◽  
Underwater Vehicle ◽  
Propulsion System ◽  
The Body ◽  
Head Losses ◽  
Current Design ◽  
And Performance ◽  
Semi Empirical ◽  
Surface Vessel

Abstract The goal of the project described is to replace the existing propulsion system of a small underwater vehicle with a solution less prone to mechanical damage and ensuring a lower risk of the entanglement of fibrous objects suspended in the body of water. Four typical marine screws are utilised in the current design of the vehicle. One possible solution of the problem is the application of waterjet propulsors located inside the body of the vehicle instead. The general condition of the application of the new solution was to secure at least the same motion control capabilities of the vehicle while the basic capability is its propulsion effectiveness at the required speed. Specific features of the considered waterjet propulsor, when compared with their application in surface vessel propulsion, are the lack of the head losses and the low significance of cavitation issues. One of the difficulties in the considered case is the small diameter of the propulsor in comparison to commercially available waterjet units, which have diameters between 0.1 [m] and 1.0 [m]. There is very little data regarding the design and performance of devices in the 0.02 to 0.05 [m] range. Methods utilised to forecast the performance of the new propulsion system are presented and results compared. These were semi-empirical calculations, numerical calculations and tests of real devices. The algorithm that is based on semi-empirical calculations is of particular interest while it offers possibility quick assessment of performance of a propulsor composed of several well defined components. The results indicate the feasibility of modification of the propulsion system for the considered vehicle if all the existing circumstances are taken into account.

PLASMON RESONANCE AND RAMAN MODES IN Pb NANOPARTICLES OBTAINED IN EXTRACT OF OPUNTIA FICUS-INDICA PLANT

NANO ◽  
2014 ◽  
Vol 09 (06) ◽  
pp. 1450070 ◽  
Author(s):  
L. P. RAMÍREZ-RODRÍGUEZ ◽  
M. CORTEZ-VALADEZ ◽  
J.-G. BOCARANDO-CHACON ◽  
H. ARIZPE-CHÁVEZ ◽  
M. FLORES-ACOSTA ◽  
...  
Keyword(s):  
Density Functional ◽  
Optical Measurements ◽  
Colloidal Systems ◽  
Absorption Bands ◽  
Functional Theory ◽  
Opuntia Ficus Indica ◽  
The Density Functional Theory ◽  
Raman Modes ◽  
Ag Clusters ◽  
Semi Empirical

Colloidal nanoparticles were obtained by green synthesis, embedded in the Opuntia ficus-indica plant extract. Optical measurements allowed us to detect two absorption bands centered in 230 nm and 298 nm. Agglomerates of Pb nanoparticles have size in the range 2–8 nm. The effective absorption cross section of spherical Pb nanoparticles was calculated by applying the Mie theory for colloidal systems and compared to optical absorption measurements of Pb nanoparticles. The Raman spectrum of the samples after the reduction of Pb , shows a band at low wavenumbers centered at 116 cm-1. Similar bands have been assigned to small Pb and Ag clusters in other experimental results. Additionally, we used the density functional theory (DFT) as well as semi-empirical methods to assign this band to radial breathing modes of Pb metal nanoparticles.

Computational investigations of mechanic, electronic and lattice dynamic properties of yttrium based compounds

2018 ◽  
Vol 32 (20) ◽  
pp. 1850214 ◽  
Author(s):  
Gökçen Dikici Yıldız ◽  
Yasin Göktürk Yıldız ◽  
Selgin AL ◽  
Ahmet İyigör ◽  
Nihat Arıkan
Keyword(s):  
Density Functional ◽  
Dynamic Properties ◽  
Harmonic Approximation ◽  
Lattice Dynamic ◽  
Electronic Band ◽  
Functional Theory ◽  
Cubic Crystal ◽  
Phonon Spectra ◽  
Density Functional Perturbation Theory ◽  
The Density Functional Theory

Electronic, mechanic and lattice dynamic properties of yttrium-based compounds, X3Y, where X = Pd, Pt and Rh were investigated using the density functional theory. The electronic band calculations demonstrated that X3Y compounds are metallic at the cubic crystal structures. The calculated elastic constants using the energy-strain method indicate that the three materials are mechanically stable. The calculated bulk modulus and Young’s modulus values suggest that the Pt3Y is stiffer than that of the other two. The type of bonding and ductility in the X3Y compounds were also evaluated based on their B/G ratios, Cauchy pressures (C[Formula: see text]–C[Formula: see text]) and band structure calculations. These compounds were found to be ductile in nature. The density functional perturbation theory was used to derive full phonon frequencies and total and projected phonon density of states. The computed full phonon spectra for X3Y compounds show that these compounds in the L12 phase are dynamically stable. Debye temperature and specific heat of these compounds were also calculated and evaluated using quasi harmonic approximation.

Site occupation, phase stability, crystal and electronic structures of the doped S phase (Al2CuMg)

2016 ◽  
Vol 30 (24) ◽  
pp. 1650165 ◽  
Author(s):  
Jianglong Gu ◽  
Huimin Gu ◽  
Yuchun Zhai ◽  
Peihua Ma
Keyword(s):  
Performance Optimization ◽  
Electronic Structures ◽  
Density Functional ◽  
S Phase ◽  
Mg Alloys ◽  
Theoretical Understanding ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
And Performance ◽  
Impurity Elements

The S phase (Al2CuMg) is an important strengthening phase for the Al–Cu–Mg alloys, which are widely used in the aerospace and transportation industries. The commonly added alloying elements (Mn, Ti, Zr) and the impurity elements (Fe and Si) in the Al–Cu–Mg alloys are always found in the S phase. First-principles calculations based on the density functional theory (DFT) were used to investigate the influence of doping Mn, Ti, Zr, Fe and Si elements on the S phase. Key findings demonstrated that these elements prefer to occupy different atomic sites in the S phase. Ti and Zr improved the structural stability of the S phase. The bulk modulus of the Fe, Si, Ti and Zr doped S phases becomes larger than that of the pure S phase. Both the crystal and electronic structures of the S phase are affected by the dopants. The results of this study provide a better theoretical understanding of the S phase, providing guidance for improved composition design and performance optimization of Al–Cu–Mg alloys.

Theoretical study of protactinium at high pressure

2005 ◽  
Vol 893 ◽  
Author(s):  
Börje Johansson ◽  
Sa Li ◽  
Eyvaz Eyvaz ◽  
Rajeev Ahuja
Keyword(s):  
High Pressure ◽  
Density Functional ◽  
The Body ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Fitting Procedure ◽  
A Value ◽  
The Density Functional Theory ◽  
Murnaghan Equation ◽  
Good Agreement

AbstractWe have studied the crystal structure of Pa metal under high pressure by means of first-principles calculations based on the density functional theory (DFT) using the generalized gradient approximation (GGA). The body centered tetragonal (bct) to orthorhombic (α-U) phase transition was calculated to take place at 29 GPa and with a volume change of 1.3%. The calculated c/a for the bct phase reaches the ideal c/a value (0.816) at around 50 GPa. A bulk modulus of 113 GPa was derived from a Murnaghan equation of state (EOS) fitting procedure. Our results are in general good agreement with recent experiment performed by Haire et al. [Phys. Rev. B 67, 134101 (2003)]. We have also calculated the phonon spectrum for fcc, bct and bcc Pa. The latter gives imaginary frequencies showing the low temperature instability of this crystallographic phase for Pa.

First principles investigation of structural, vibrational and thermal properties of black and blue phosphorene

2018 ◽  
Vol 32 (12) ◽  
pp. 1850151 ◽  
Author(s):  
R. M. Arif Khalil ◽  
Javed Ahmad ◽  
Anwar Manzoor Rana ◽  
Syed Hamad Bukhari ◽  
M. Tufiq Jamil ◽  
...  
Keyword(s):  
Thermal Properties ◽  
First Principles ◽  
Density Functional ◽  
State Energy ◽  
Harmonic Approximation ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Temperature Lattice ◽  
Blue Phase ◽  
Blue Phosphorene

In this investigation, structural, dynamical and thermal properties of black and blue phosphorene (P) are presented through the first principles calculations based on the density functional theory (DFT). These DFT calculations depict that due to the approximately same values of ground state energy at zero Kelvin and Helmholtz free energy at room-temperature, it is expected that both structures can coexist at transition temperature. Lattice dynamics of both phases were investigated by using the finite displacement supercell approach. It is noticed on the basis of harmonic approximation thermodynamic calculations that the blue phase is thermodynamically more stable than the black phase above 155 K.

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