scholarly journals Elastic Properties of α- and β-phases of Li3N

2009 ◽  
Vol 1 (2) ◽  
pp. 182-191 ◽  
Author(s):  
M. A. Hossain ◽  
A.K.M. A Islam ◽  
F. N. Islam
Keyword(s):  
Debye Temperature ◽  
Elastic Properties ◽  
Elastic Constants ◽  
First Principles ◽  
Phonon Dispersion ◽  
Wavelength Region ◽  
Phonon Dispersion Curves ◽  
Long Wavelength ◽  
Α Phase ◽  
First Time

Investigations of elastic properties of Li3N in both α- and β-phases have been made by first-principles methods (HF-LCAO, DFT as implemented in CRYSTAL98 and in CASTEP). The theoretical equation of state of the α-phase (D46h structure) produced by our total-energy calculations is compared with the experimental EOS. Five independent elastic constants are calculated for the first time for both the phases. These are compared with the available four elastic constants of α-Li3N estimated from the slopes of the acoustic branches in the long wavelength region of the measured phonon dispersion curves. The aggregate elastic moduli (B, G, E), the Poisson’s ratio (ν) and the Debye temperature ΘD as a function of pressure are also calculated and the results discussed.Keywords: Li3N; α- and β-phases; Elastic properties; Debye temperature.©?2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v1i2.1763     

scholarly journals Elastic Behavior of γ-Li3N under Pressure

2011 ◽  
Vol 3 (3) ◽  
pp. 569-574
Author(s):  
M. A. Hossain ◽  
A. K. M. A. Islam
Keyword(s):  
Debye Temperature ◽  
Elastic Properties ◽  
Elastic Constants ◽  
First Principles ◽  
Elastic Moduli ◽  
Gamma Transition ◽  
Elastic Behavior ◽  
Gamma Phase ◽  
First Time ◽  
First Principles Method

The elastic properties of gamma-Li3N have been studied for the first time by first-principles method. Three independent elastic constants, aggregate elastic moduli (B, G, E), Poisson’s ratio and Debye temperature are calculated as a function of pressure from 37.12 (beta to gamma transition value)  to 200 GPa and the implications of the results are discussed.Keywords: Li3N; Gamma-phase; Elastic properties; Debye temperature.© 2011 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi:10.3329/jsr.v3i3.7832               J. Sci. Res. 3 (3), 579-584 (2011)

scholarly journals Phonon Dynamics and Acoustic and Thermodynamic Properties of Pt57.5Cu14.7Ni5.3P22.5 Bulk Metallic Glass

2021 ◽  
Vol 13 (1) ◽  
pp. 21-29
Author(s):  
R. R. Koireng ◽  
P. C. Agarwal ◽  
A. Gokhroo
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Phonon Dispersion ◽  
Wavelength Region ◽  
Dispersion Curves ◽  
Phonon Dispersion Curves ◽  
Appropriate Behavior ◽  
Long Wavelength ◽  
Transverse Modes ◽  
Reported Data

The phonon dispersion curves for Pt57.5Cu14.7Ni5.3P22.5 bulk metallic glass (BMG) are computed employing various dielectric screenings using the simple model given by Bhatia and Singh. The force constants β and δ for computing the dispersion curves are calculated from the elastic constants i.e. bulk modulus (B) and shear modulus (G) along with the calculated value of force constant κe of the material of the glass for the first time. The results of the phonon dispersion curves show appropriate behavior in the long wavelength region in detail for both the longitudinal and transverse modes and give insight regarding the acoustic and thermal properties of the BMG. The transverse sound velocity and the longitudinal velocities with various dielectric screening are calculated from the dispersion curves in the long wavelength region. The corresponding thermodynamic property (Debye temperature) is calculated for different dielectric screenings. The theoretical results predicted are in a good agreement with the reported data in the literature for the Pt57.5Cu14.7Ni5.3P22.5 BMG and may be used for correlating other properties.

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.

First-principles study of electronic structure, chemical bonding and elastic properties for new superconductor CaFeAs2

2017 ◽  
Vol 31 (02) ◽  
pp. 1650263
Author(s):  
J. G. Yan ◽  
Z. J. Chen ◽  
G. B. Xu ◽  
Z. Kuang ◽  
T. H. Chen ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Elastic Properties ◽  
Density Of States ◽  
First Principles ◽  
Elastic Anisotropy ◽  
First Principles Calculation ◽  
Hard Material ◽  
Dirac Cone ◽  
First Time ◽  
New Superconductor

Using first-principles calculation we investigated the structural, electronic and elastic properties of paramagnetic CaFeAs2. Our results indicated that the density of states (DOS) was dominated predominantly by Fe-3[Formula: see text] states at Fermi levels, and stronger hybridization exists between As1 and As1 atoms. Three hole pockets are formed at [Formula: see text] and Z points, and two electronic pockets are formed at A and E points. The Dirac cone-like bands appear near B and D points. For the first time we calculated the elastic properties and found that CaFeAs2 is a mechanically stable and moderately hard material, it has elastic anisotropy and brittleness, which agrees well with the bonding picture and the calculation of Debye temperature ([Formula: see text]).

scholarly journals Pressure Effect on Elastic Constants and Related Properties of Ti3Al Intermetallic Compound: A First-Principles Study

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2015 ◽  
Author(s):  
Xianshi Zeng ◽  
Rufang Peng ◽  
Yanlin Yu ◽  
Zuofu Hu ◽  
Yufeng Wen ◽  
...  
Keyword(s):  
Intermetallic Compound ◽  
Debye Temperature ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Mechanical Stability ◽  
Theoretical Data ◽  
Young’S Moduli ◽  
Anisotropic Factor ◽  
Isotropic Pressure

Using first-principles calculations based on density functional theory, the elastic constants and some of the related physical quantities, such as the bulk, shear, and Young’s moduli, Poisson’s ratio, anisotropic factor, acoustic velocity, minimum thermal conductivity, and Debye temperature, are reported in this paper for the hexagonal intermetallic compound Ti 3 Al. The obtained results are well consistent with the available experimental and theoretical data. The effect of pressure on all studied parameters was investigated. By the mechanical stability criteria under isotropic pressure, it is predicted that the compound is mechanically unstable at pressures above 71.4 GPa. Its ductility, anisotropy, and Debye temperature are enhanced with pressure.

AB INITIO STUDY OF PHONON DISPERSION AND ELASTIC PROPERTIES OF L12 INTERMETALLICS Ti3Al AND Y3Al

2013 ◽  
Vol 27 (30) ◽  
pp. 1350224 ◽  
Author(s):  
N. ARIKAN ◽  
M. ERSEN ◽  
H. Y. OCAK ◽  
A. İYIGÖR ◽  
A. CANDAN ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Phonon Dispersion ◽  
High Symmetry ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Phonon Dispersion Curves ◽  
Lattice Constants ◽  
Density Functional Perturbation Theory ◽  
Phonon Properties

In this paper, the structural, elastic and phonon properties of Ti 3 Al and Y 3 Al in L1 2( Cu 3 Al ) phase are studied by performing first-principles calculations within the generalized gradient approximation. The calculated lattice constants, static bulk moduli, first-order pressure derivative of bulk moduli and elastic constants for both compounds are reported. The phonon dispersion curves along several high-symmetry lines at the Brillouin zone, together with the corresponding phonon density of states, are determined using the first-principles linear-response approach of the density functional perturbation theory. Temperature variations of specific heat in the range of 0–500 K are obtained using the quasi-harmonic model.

Electronic and elastic properties of AIIB2IIIC4VI defect-chalcopyrite semiconductors

2019 ◽  
Vol 33 (28) ◽  
pp. 1950340 ◽  
Author(s):  
S. Chandra ◽  
Anita Sinha ◽  
V. Kumar
Keyword(s):  
Debye Temperature ◽  
Elastic Properties ◽  
Density Functional ◽  
Elastic Stiffness ◽  
Lattice Constants ◽  
Chalcopyrite Semiconductors ◽  
Principle Density Functional Theory ◽  
Experimental Values ◽  
G Ratio ◽  
First Time

The electronic and elastic properties of [Formula: see text] defect-chalcopyrite semiconductors have been studied using first-principle density functional theory (DFT) calculations. The lattice constants, energy band gap, elastic stiffness constants, bulk modulus, shear modulus, shear anisotropy factor, Young’s modulus, Debye temperature, Poisson’s ratio and B/G ratio have been computed. The values of elastic constants of 14 defect-chalcopyrites and Debye temperature for 18 compounds have been reported for the first time. The obtained results are in reasonable agreement with the experimental values in few cases where experiments are performed and reported values.

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