Effect of Sr - Transition Metal Substitution on Electronic and Mechanical Properties of Mg2Si: A DFT Study

2021 ◽  
Vol 14 (3) ◽  
pp. 255-265
Keyword(s):  
Mechanical Properties ◽  
Elastic Constants ◽  
Density Functional ◽  
Plane Waves ◽  
Three Dimensional ◽  
Anisotropy Parameter ◽  
Electronic Band ◽  
The Density Functional Theory ◽  
Direct Band ◽  
Quantum Espresso

Abstract: Recently, magnesium alloys have attracted scientific interest due to their technological importance in thermoelectric, piezoelectric, photo-voltaic and infrared photonics applications. The electronic and elastic properties of MgXSi (X = Mg, Sr) compounds were investigated in this work, using the density functional theory (DFT) with pseudo-potential plane-waves (PPW) approach as implemented in Quantum Espresso code. The results of the elastic constants of Mg2Si are in agreement with the previous theoretical results and favourably compared with experimental data. The electronic band structures of these semiconductors were calculated to give narrow indirect and direct band gaps of Mg2Si and MgSrSi, respectively. Our results show that the two compounds are mechanically stable. The Pugh’s ratio, B/G, indicated that Mg2Si and MgSrSi are brittle and ductile in nature. The estimated anisotropy parameter, A, shows that Mg2Si has a higher degree of elastic isotropy in comparison to MgSrSi. Three-dimensional (3D) projection of Young’s modulus and area modulus of the compounds was presented. Keywords: Electronic structure, Elastic constants, Mechanical properties, Mg2Si, MgSrSi. PACS: 31.15.A-, 62.20.F-, 71.55.-i, 71.20.Be.

scholarly journals Structural Optimization, Electronic Band Structure, Mechanical and Thermodynamics Properties of Fe3Al

2021 ◽  
pp. 1-11
Author(s):  
I. S. Okunzuwa ◽  
E. Aigbekaen Eddy
Keyword(s):  
Density Functional ◽  
Electronic Band Structure ◽  
Plane Waves ◽  
State Density ◽  
Structural Parameter ◽  
Mechanical And Thermal Properties ◽  
Energy Bands ◽  
Electronic Band ◽  
Salt Structure ◽  
Quantum Espresso

We calculated the structural, electronic, mechanical and thermal properties of Fe3Al semiconducting using Quantum ESPRESSO, an open source first principles code based on density-functional theory, plane waves, and pseudopotentials. Structural parameter results (equilibrium lattice parameters, bulk modulus and its derivative pressure) have been reported. The underestimated band gap is obtained along with higher state density and energy bands around the fermi level. Mechanical properties of the rock-salt structure of Fe3Al, such as, shear modulus (G), Young’s modulus (E), and Poisson’s ratio () were investigated. The thermodynamic parameters are also present. The results are in good agreement with the available experimental and other theoretical results.

Structural, electronic and elastic properties of the B2-ScM (M =Au, Hg and Tl) intermetallic compounds: Ab initio calculations

2015 ◽  
Vol 04 (04) ◽  
pp. 1550020
Author(s):  
Ahmad A. Mousa ◽  
Jamil M. Khalifeh
Keyword(s):  
Mechanical Properties ◽  
Bulk Modulus ◽  
Intermetallic Compounds ◽  
Elastic Constants ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Local Density ◽  
Full Potential ◽  
Generalized Gradient ◽  
Electronic Band

Structural, electronic, elastic and mechanical properties of ScM (M[Formula: see text][Formula: see text][Formula: see text]Au, Hg and Tl) intermetallic compounds are studied using the full potential-linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT), within the generalized gradient approximation (GGA) and the local density approximation (LDA) to the exchange-correlation approximation energy as implemented in the Wien2k code. The ground state properties including lattice parameters, bulk modulus and elastic constants were all computed and compared with the available previous theoretical and experimental results. The lattice constant was found to increase in contrast to the bulk modulus which was found to decrease with every substitution of the cation (M) starting from Au till Tl in ScM. Both the electronic band structure and density-of-states (DOS) calculations show that these compounds possess metallic properties. The calculated elastic constants ([Formula: see text], [Formula: see text] and [Formula: see text] confirmed the elastic stability of the ScM compounds in the B2-phase. The mechanical properties and ductile behaviors of these compounds are also predicted based on the calculated elastic constants.

Study of first principles on anisotropy and elastic constants of YAl3 compound

2020 ◽  
Vol 98 (4) ◽  
pp. 357-363
Author(s):  
Tahsin Özer
Keyword(s):  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Data ◽  
Anisotropic Behavior ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
The Density Functional Theory ◽  
Quantum Espresso

Using the density functional theory (DFT) calculations, the structural optimization of the YAl3 compound was performed on the generalized gradient approximation (GGA) with quantum ESPRESSO (QE) software. Elastic constants were calculated after the optimization process. Polycrystalline quantities, such as bulk and shear modulus, Young’s modulus, and Poisson’s ratio, were determined using calculated elastic constants. The anisotropy of the compound was studied in detail. As a result of the calculations made, it was observed that the YAl3 compound exhibited mechanically stable structure and anisotropic behavior. In the ht2-YAl3 phase, the effect of pressure on physical properties was investigated in detail. The obtained results were compared with the existing experimental and other theoretical data.

Mechanical properties and variation in SOC going from La to Nd in intermetallic RIn3 and RSn3 (R = La, Ce, Pr, Nd)

RSC Advances ◽  
2015 ◽  
Vol 5 (49) ◽  
pp. 39416-39423 ◽  
Author(s):  
M. Shafiq ◽  
Iftikhar Ahmad ◽  
S. Jalali-Asadabadi
Keyword(s):  
Mechanical Properties ◽  
Density Functional Theory ◽  
Rare Earth ◽  
Density Functional ◽  
Plane Waves ◽  
Orbital Method ◽  
Full Potential ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Theory Framework

The cubic rare-earth intermetallics RIn3 and RSn3 (R = La, Ce, Pr, Nd) have been investigated using the full potential linearized augmented plane waves plus local orbital method in the density functional theory framework.

Structural and Mechanical Properties of Ti1-XAlxN Studied by Ab Initio

2011 ◽  
Vol 383-390 ◽  
pp. 3331-3337 ◽  
Author(s):  
Xin Tan ◽  
Yu Qing Li ◽  
Xue Jie Liu ◽  
Yan Hui Xie
Keyword(s):  
Mechanical Properties ◽  
Elastic Constants ◽  
Cohesive Energy ◽  
Density Functional ◽  
Lattice Parameter ◽  
Industrial Applications ◽  
Mechanical And Thermal Properties ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Ductile Behavior

Ti1-xAlxN films have been shown to exhibit superior mechanical and thermal properties and are thus widely used for industrial applications. We have studied the structural and mechanical properties of fcc-TiN and fcc-Ti1-xAlxN solid solution (x=0.25 and x=0.5), using first principles calculations based on the density functional theory. These calculations provide the lattice parameter, total energy, cohesive energy, elastic constants, etc, of the TiN lattice and when Al atoms replace Ti atoms in the TiN lattice. With regard to the cohesive energy of TiN and fcc-Ti1-xAlxN, we can obtain that the fcc-Ti1-xAlxN is metastable. Via comparation and analysis, it’s shown that the lattice parameter, cohesive energy and elastic constants decrease with increasing the content of Al. However, ductile behavior is promoted by Al addition.

scholarly journals Performance of SCAN Meta-GGA Functionals on Nonlinear Mechanics of Graphene-Like g-SiC

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 120
Author(s):  
Qing Peng
Keyword(s):  
Mechanical Properties ◽  
Density Functional ◽  
Large Strains ◽  
Two Dimensional ◽  
Nonlinear Mechanics ◽  
Generalized Gradient ◽  
Mechanics Of Materials ◽  
Nonlinear Mechanical ◽  
Direct Band ◽  
Simulations And Modeling

Although meta-generalized-gradient approximations (meta-GGAs) are believed potentially the most accurate among the efficient first-principles calculations, the performance has not been accessed on the nonlinear mechanical properties of two-dimensional nanomaterials. Graphene, like two-dimensional silicon carbide g-SiC, has a wide direct band-gap with applications in high-power electronics and solar energy. Taken g-SiC as a paradigm, we have investigated the performance of meta-GGA functionals on the nonlinear mechanical properties under large strains, both compressive and tensile, along three deformation modes using Strongly Constrained and Appropriately Normed Semilocal Density Functional (SCAN) as an example. A close comparison suggests that the nonlinear mechanics predicted from SCAN are very similar to that of Perdew-Burke-Ernzerhof (PBE) formulated functional, a standard Density Functional Theory (DFT) functional. The improvement from SCAN calculation over PBE calculation is minor, despite the considerable increase of computing demand. This study could be helpful in selection of density functionals in simulations and modeling of mechanics of materials.

Study of thermo-elastic and lattice dynamics properties of half-Heusler compounds XMgAl (X = Li, Na) by computational investigations

2019 ◽  
Vol 33 (08) ◽  
pp. 1950093 ◽  
Author(s):  
A. Afaq ◽  
Abu Bakar ◽  
M. Rizwan ◽  
M. Aftab Fareed ◽  
H. Bushra Munir ◽  
...  
Keyword(s):  
Debye Temperature ◽  
Elastic Constants ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Dynamic Properties ◽  
Mechanical Parameters ◽  
Heusler Compounds ◽  
Generalized Gradient ◽  
Text Type ◽  
Quantum Espresso

In this study, thermo-elastic and lattice dynamic properties of XMgAl (X = Li, Na) half-Heusler compounds are investigated using density functional theory implemented in WIEN2k and Quantum ESPRESSO codes. Generalized gradient approximation (GGA) as an exchange correlation function has been used in Kohn–Sham equations. Firstly, the structure of these Heusler compounds is optimized and then these optimized parameters are used to find three elastic constants [Formula: see text], [Formula: see text] and [Formula: see text] for [Formula: see text] type structures. Three elastic constants are then used to determine different elastic moduli like bulk modulus, shear modulus, Young’s modulus and other mechanical parameters like Pugh’s ratio, Poisson’s ratio, anisotropic ratio, sound velocities, Debye temperature and melting temperature. On behalf of these mechanical parameters, the brittle/ductile nature and isotropic/anisotropic behavior of the materials has been studied. Different regions of vibrational modes in the materials are also discussed on behalf of Debye temperature calculations. The vibrational properties of the half-Heusler compounds are computed using Martins–Troullier pseudo potentials implemented in Quantum ESPRESSO. The phonon dispersion curves and phonon density of states in first Brillion zone are obtained and discussed. Reststrahlen band of LiMgAl is found greater than NaMgAl.

Effect of Alloying Elements V, Cr and Ni on the Electronic Structure and Mechanical Properties of FeAl from First-Principles Calculation

2014 ◽  
Vol 887-888 ◽  
pp. 378-383 ◽  
Author(s):  
Yu Chen ◽  
Zheng Jun Yao ◽  
Ping Ze Zhang ◽  
Dong Bo Wei ◽  
Xi Xi Luo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electronic Structure ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Valence Bond ◽  
Ternary Alloys ◽  
First Principles Calculation ◽  
Structure Stability ◽  
Alloying Element

The structure stability, mechanical properties and electronic structures of B2 phase FeAl intermetallic compounds and FeAl ternary alloys containing V, Cr or Ni were investigated using first-principles density functional theory calculations. Several models are established. The total energies, cohesive energies, lattice constants, elastic constants, density of states, and the charge densities of Fe8Al8 and Fe8XAl7 ( X=V, Cr, Ni ) are calculated. The stable crystal structures of alloy systems are determined due to the cohesive energy results. The calculated lattice contants of Fe-Al-X ( X= V, Cr, Ni) were found to be related to the atomic radii of the alloy elements. The calculation and analysis of the elastic constants showed that ductility of FeAl alloys was improved by the addition of V, Cr or Ni, the improvement was the highest when Cr was used. The order of the ductility was as follows: Fe8CrAl7 > Fe8NiAl7 > Fe8VAl7 > Fe8Al8. The results of electronic structure analysis showed that FeAl were brittle, mainly due to the orbital hybridization of the s, p and d state electron of Fe and the s and p state electrons of Al, showing typical characteristics of a valence bond. Micro-mechanism for improving ductility of FeAl is that d orbital electron of alloying element is maily involved in hybridization of FeAl, alloying element V, Cr and Ni decrease the directional property in bonding of FeAl.

FIRST PRINCIPLE CALCULATION OF ELECTRONIC BAND STRUCTURE AND OPTICAL PROPERTIES OF KIO3

2009 ◽  
Vol 23 (10) ◽  
pp. 2405-2412
Author(s):  
HARUN AKKUS ◽  
BAHATTIN ERDINC
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Electronic Band ◽  
Principle Calculation ◽  
First Principle Calculation ◽  
Functional Methods ◽  
A Value ◽  
Direct Band

The electronic band structure and optical properties of the ferroelectric single crystal KIO 3 have been investigated using the density functional methods. The calculated band structure for KIO 3 evidences that the crystal has a direct band gap with a value of 2.83 eV. The structural optimization has been performed. The real and imaginary parts of dielectric function, energy-loss function for volume and surface, and refractive index are calculated along the crystallographic axes.

scholarly journals Essential Electronic Properties of Silicon Nanotubes

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2475
Author(s):  
Hsin-Yi Liu ◽  
Ming-Fa Lin ◽  
Jhao-Ying Wu
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Chiral Angle ◽  
Silicon Nanotubes ◽  
Critical Transitions ◽  
The Density Functional Theory ◽  
Essential Properties ◽  
Direct Band ◽  
Mixing States ◽  
Narrow Gaps

In this work, the various electronic properties of silicon nanotubes (SiNTs) were investigated by the density functional theory. The cooperative and competitive relationships between the chiral angle, periodic boundary conditions, and multi-orbital hybridizations create unusual narrow gaps and quasi-flat bands in the ultra-small armchair and zigzag tubes, respectively. The features varied dramatically with tube radii. Armchair SiNTs (aSiNTs) have an indirect-to-direct band gap transition as their radius is increased to a particular value, while zigzag SiNTs (zSiNTs) present a metal-semiconductor transition. The projected density of states was used to elucidate the critical transitions, and the evolution of p and s orbital mixing states during the process are discussed in detail. The information presented here provides a better understanding of the essential properties of SiNTs.

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