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1.
Xinyu Zhang Zhouwen Chen Changzeng Fan Mingzhen Ma Qin Jing Riping Liu 《固体物理学:研究快报》2009,3(9):299-301
The energetic, mechanical and electronic properties as a function of composition for Rex W1–x C alloys in the WC structure have been investigated. It has been demonstrated that the shear modulus of WC can be enhanced by alloying with a small amount of Re, to a maximum shear modulus of 311 GPa at x = 0.23. The designed alloy is energetically stable and could be expected to be a potential extremely hard transition‐metal monocarbide, which is attributed to the strong metal–metalloid interaction with modulated valence electron concentration with respect to WC. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
2.
We have performed first-principles study on electronic structure and elastic properties of Ti2SC. The absence of band gap at the Fermi level and the finite value of the density of states at the Fermi energy reveal the metallic behavior of this compound. The five independent elastic constants were derived and the bulk modulus, Young's modulus, shear modulus, and Poisson's ratio were determined. The high bulk modulus and hardness was found to be originated from the strong Ti 3d-S 2p hybridization. Such strong MA bonding is unusual in the MAX phases studied so far. Ti2SC is elastically stable and exhibits highly elastic isotropy. 相似文献
3.
The full‐potential linearized augmented plane wave method with the generalized gradient approximation for the exchange and correlation potential (LAPW‐GGA) is used to understand the electronic and elastic properties of the first thorium‐containing nitride perovskite TaThN3. Total and partial density of states, charge distributions as well as the elastic constants, bulk modulus, compressibility, shear modulus, Young modulus and Poisson ratio are obtained for the first time and analyzed in comparison with cubic ThN. The chemical bonding in TaThN3 is a combination of ionic Th–N and of mixed covalent–ionic Ta–N bonds. The cubic TaThN3 is semiconducting with the direct gap at about 0.65 eV. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
4.
A model pseudopotential depending on an effective core radius treated as a parameter is used for alkaline earth metals in bcc and fcc phases to study the Binding energy, Interatomic interactions, phonon dispersion curves, Phonon density of states, Debye-Waller factor, mean square displacement, Debye-Waller temperature parameters, dynamical elastic constants (C11, C12 and C44), bulk modulus (B), shear modulus (C′), deviation from Cauchy relation (C12−C44), Poisson's ratio (σ), Young's modulus (Y), behavior of phonon frequencies in the elastic limit independent of the direction (Y1), limiting value in the [1 1 0] direction (Y2), degree of elastic anisotropy (A) and propagation velocities of the elastic waves. The contribution of s-like electrons is incorporated through the second-order perturbation theory due to model potential. The theoretical results are compared with the existing experimental data. A good agreement between theoretical investigations and experimental findings has confirmed the ability of our potential to yield large numbers of lattice mechanical properties of certain alkaline earth metals. 相似文献
5.
Ab initio calculations were performed to investigate electronic and elastic properties of the newly discovered 7.5 K superconductor:
layered Nb2InC. As a result, electronic bands, total and site-projected l—decomposed density of states at the Fermi level, shape of the Fermi surface for Nb2InC were obtained for the first time. Besides, independent elastic constants, bulk modulus, compressibility, shear modulus,
Young’s modulus, Poisson’s ratio together with the elastic anisotropy parameters and indicator of brittle/ductile behavior
of Nb2InC were evaluated and analyzed in comparison with the available data. 相似文献
6.
A. Bouhemadou Y. Al-Douri R. Khenata K. Haddadi 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,71(2):185-194
We have investigated the structural, elastic, electronic, optical and
thermal properties of c-SiGe2N4 by using the ultrasoft
pseudopotential density functional method within the generalized gradient
approximation. The calculated structural parameters, including the lattice
constant, the internal free parameter, the bulk modulus and its pressure
derivative are in agreement with the available data. The independent elastic
constants and their pressure dependence, calculated using the static finite
strain technique, satisfy the requirement of mechanical stability,
indicating that c-SiGe2N4 compound could be stable. We derive the
shear modulus, Young’s modulus, Poisson’s ratio and Lamé’s coefficients
for ideal polycrystalline c-SiGe2N4 aggregate in the framework of
the Voigt-Reuss-Hill approximation. We estimate the Debye temperature of
this compound from the average sound velocity. Band structure, density of
states, Mulliken charge populations and pressure coefficients of energy band
gaps are investigated. Furthermore, in order to understand the optical
properties of c-SiGe2N4, the dielectric function, refractive index,
extinction coefficient, optical reflectivity and electron energy loss are
calculated for radiation up to 40 eV. Thermal effects on some macroscopic
properties of c-SiGe2N4 are predicted using the quasi-harmonic
Debye model in which the lattice vibrations are taken into account. We have
obtained successfully the variations of the primitive cell volume, volume
expansion coefficient, heat capacities and Debye temperature with pressure
and temperature in the ranges of 0–40 GPa and 0–2000 K. For the first
time, the numerical estimates of the elastic constants and related
parameters, and the thermal properties are performed for
c-SiGe2N4. 相似文献
7.
J. K. Baria 《Czechoslovak Journal of Physics》2004,54(4):469-485
A model pseudopotential depending on an effective core radius but otherwise parameter free is used to study the interatomic
interactions, phonon dispersion curves (inq and r-space analysis), phonon density of states, mode Grüneisen parameters, dynamical elastic constants (C
11,C
12 andC
44), bulk modulus (B), shear modulus (C′), deviation from Cauchy relation (C
12–C
44), Poisson’s ratio (σ), Young’s modulus (Y), behavior of phonon frequencies in the elastic limit independent of the direction (Y
1), limiting value in the [110] direction (Y
2), degree of elastic anisotropy (A), maximum frequencyω
max, mean frequency 〈ω〉, 〈ω
2〉1/2=(〈ω〉/〈ω
−1〉)1/2, fundamental frequency 〈ω
2〉, and propagation velocities of the elastic constants in Cu, Ag, Au, Ni, Pd, and Pt. The contribution of s-like electrons
is calculated in the second-order perturbation theory for the model potential while that of d-like electrons is taken into
account by introducing repulsive short-range Born-Mayer like term. Very recently proposed screening function due to Sarkar
et al. has been used to obtain the screened form factor. The theoretical results are compared with experimental findings wherever
possible. A good agreement between theoretical investigations and experimental findings has proved the ability of our model
potential for predicting a large number of physical properties of transition metals. 相似文献
8.
A. Bouhemadou R. Khenata M. Chegaar 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(3):209-215
Using first-principles density functional calculations, the effect of high
pressures, up to 20 GPa, on the structural and elastic properties of
Zr2AlX and Ti2AlX, with X = C and N, were studied by means of the
pseudo-potential plane-waves method. Calculations were performed within the
local density approximation to the exchange-correlation approximation
energy. The lattice constants and the internal parameters are in agreement
with the available results. The elastic constants and their pressure
dependence are calculated using the static finite strain technique. We
derived the bulk and shear moduli, Young's moduli and Poisson's ratio for
ideal polycrystalline Zr2AlX and Ti2AlX aggregates. We estimated
the Debye temperature of Zr2AlX and Ti2AlX from the average sound
velocity. This is the first quantitative theoretical prediction of the
elastic properties of Zr2AlC, Zr2AlN and Ti2AlN compounds,
and it still awaits experimental confirmation. 相似文献
9.
S. Ramasubramanian M. Rajagoplan R. Thangavel J. Kumar 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(2):265-268
Elastic and Thermodynamical properties of Ti1-xZrxC have been investigated using LAPW + lo within the density-functional theory with the generalized gradient approximation.
We have studied the stability of the alloy Ti1-xZrxC as a function of Zr composition in rocksalt (B1) structure by calculating the elastic constants C11, C12 and C44 using the tetragonal and trigonal distortions. Mechanical properties such as Poisson ratio, bulk, shear and Young’s modulii
of Ti1-xZrxC are calculated. The Debye temperature and hardness are also computed for the first time to our knowledge for Ti1-xZrxC in various compositions. 相似文献
10.
The electronic properties and elastic parameters of the superconducting nanolaminate Ti2InC are analyzed using the ab initio full-potential linearized augmented-plane-wave (FLAPW) method with the generalized gradient approximation (GGA) of the local spin density. The equilibrium parameters of the crystal lattice, the band structure, the total and partial densities of states, and the Fermi surface are determined within a unified approach. The independent elastic constants, the bulk modulus, and the shear modulus are calculated, and the elastic parameters are numerically estimated for the first time for polycrystalline Ti2InC. 相似文献
11.
M. Gupta K. L. Baluja 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):475-483
Electron-H2S collision process is studied using the R-matrix method. Nine low-lying states of H2S molecule are considered in the R-matrix formalism to obtain elastic integral, differential, momentum transfer and excitation cross sections for this scattering
system. We have represented our target states using configuration interaction (CI) wavefunctions. We obtained adequate representation
of vertical spectrum of the target states included in the scattering calculations. The cross sections are compared with the
experiment and other theoretical results. We have obtained good agreement for elastic and momentum transfer cross sections
with experiment for entire energy range considered. The differential cross sections are in excellent agreement with experiment
in the range 3–15 eV. A prominent feature of this calculation is the detection of a shape resonance in 2B2 symmetry which decays via dissociative electron attachment (DEA). Born correction is applied for the elastic and dipole allowed
transition to account for higher partial waves excluded in the R-matrix calculation. The electron energy range is 0.025–15 eV. 相似文献
12.
K. Araki T. Goto Y. Nemoto T. Yanagisawa B. Lüthi 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(3):257-259
The temperature dependence of the elastic constants in
Tb3Ga5O12 was measured and analysed with a simple crystal
field model. The magneto-elastic coupling constants have been deduced from
this experiment. The coupling constant gΓ5, related to the
c44 mode, is anomalously large. These coupling constants are important
for the interpretation of the phonon Hall effect. 相似文献
13.
M2AlC phases, where M is a transition metal, are layered ternary compounds that possess unusual properties. In this paper, we have calculated the elastic properties of M2AlC, with M=Ti, V, Cr, Nb and Ta, by means of ab initio total energy calculations using the projector augmented-wave method. We have derived the bulk and shear moduli, Young's moduli and Poisson's ratio for ideal polycrystalline M2AlC aggregates. We have estimated the elastic modulus of Cr2AlC with 357.7 GPa while the values of all other phases are in the range 309±10 GPa. We suggest that this can be understood based on the calculated bond energies for the M-C bonds. Furthermore, our results indicate a profound elastic anisotropy of M2AlC even compared to materials with a well-established anisotropic character such as α-alumina. Finally, we have estimated the Debye temperatures of M2AlC from the average sound velocity. 相似文献
14.
We have performed ab-initio total energy calculations using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT) to study structural, elastic, mechanical, electronic, and optical properties of cubic Mg2TiO4. The calculated lattice parameter a is in good agreement with the experimental values. The independent elastic constants are calculated. The mechanical properties including bulk, shear and Young’s modulus, Poisson’s coefficient, compressibility and Lamé’s constants are obtained using the Voigt-Reuss-Hill method. Debye temperature is estimated using the Debye-Grüneisen model. Band structure, density of states and charge densities are shown and analyzed. In order to clarify the mechanism of optical transitions of cubic Mg2TiO4, the complex dielectric function, refractive index, extinction coefficient, reflectivity, absorption coefficient, loss function and complex conductivity function are calculated. 相似文献
15.
D. Varshney G. Joshi 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(4):523-534
The present paper addresses the high-pressure phase transformation and
mechanical properties of Ga1-xInxAs (x = 0.25, 0.5 and 0.75) by
formulating an effective interionic interaction potential. This potential
consists of the long-range Coulomb and charge transfer caused by the
deformation of the electron shells of the overlapping ions and the
Hafemeister and Flygare type short-range overlap repulsion extended upto the
second neighbor ions and the van der Waals (vdW) interaction. The estimated
values of phase transition pressure and the vast volume discontinuity in
pressure-volume (PV) phase diagram indicate the structural phase transition
from zinc blende (B3) to rock salt (B1). The equation of state curves plotted
between V (P)/ V (0) and pressure are for both the zincblende (B3) and rocksalt
(B1) structures. Further, the variations of the second and third order
elastic constants with pressure have followed a systematic trend, which are
almost identical to those exhibited by the observed data measured for other
compounds of this family. 相似文献
16.
Spin polarized ab initio calculations have been carried out to study the structural, electronic, elastic and thermal properties of RHg (R = Ce, Pr, Eu and Gd) intermetallic compounds in B2 structure. The calculations have been performed by using both generalized gradient approximation (GGA) and local spin density approximation (LSDA). The calculated value of lattice constant (a 0) for these compounds with GGA is in better agreement with the experimental data than those with LSDA. Bulk modulus (B), first-order pressure derivative of bulk modulus and magnetic moment (μ B ) are also presented. The energy band structure and electron density of states show the occupancy of 4f states for light as well as heavy rare earth atom. The elastic constants are predicted from which all the related mechanical properties like Poisson’s ratio (σ), Young’s modulus (E), shear modulus (G H ) and anisotropy factor (A) are calculated. The ductility or brittleness of these compounds is predicted from Pugh’s rule (B/G H ) and Cauchy pressure (C 12 ? C 44). The Debye temperature (θ D ) is estimated from the average sound velocity, which have not been calculated and measured yet. 相似文献
17.
D. Varshney R. Sapkale G. J. Dagaonkar M. Varshney 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,79(4):495-502
The mechanical, thermodynamical and elastic properties of Hg0.91Mn0.09Te compound are calculated by formulating an effective interionic interaction potential. This potential consists of the long-range
Coulomb, three body force parameter, the Hafemeister and Flygare type short-range overlap repulsion extended upto the second
neighbor ions and the van der Waals (vdW) interaction. The estimated values of phase transition pressure have revealed reasonably
good agreement with the available experimental data on the phase transition pressure P
t
= 11.5 GPa and the vast volume discontinuity in pressure-volume (PV) phase diagram indicate the structural phase transition
from zincblende (B3) to rock salt (B1) structure. Later on, the Poisson’s ratio ν, the ratio R
S/B
of S (Voigt averaged
shear modulus) over B (bulk modulus), elastic anisotropy parameter, elastic wave velocity, average wave velocity and Debye temperature as functions
of pressure is calculated. From Poisson’s ratio and the ratio R
S/B
it is inferred that Hg0.91Mn0.09Te is brittle in nature in both B3 phase
and B1 phase. To our knowledge this is the first quantitative theoretical prediction of the pressure dependence of ductile
(brittle) nature of Hg0.91Mn0.09Te compounds and still awaits experimental confirmations. 相似文献
18.
We perform a first-principles study on the electronic structure and elastic properties of TiaA1C with an antiperovskite structure. The absence of band gap at the Fermi level and the finite value of the density of states at the Fermi energy reveal the metallic behavior of this compound. The elastic constants of Ti3AlC are derived yielding c11 = 356 GPa, c12 = 55 GPa, c44 = 157 GPa. The bulk modulus B, shear modulus G and Young's modulus E are determined to be 156, 151 and 342 GPa, respectively. These properties are compared with those of Ti3AlC2 and Ti2AlC with a layered structure in the Ti-Al-C system and FeaAlC with the same antiperovskite structure. 相似文献
19.
Using ab initio calculations, we have studied the structural, electronic and elastic properties of M2SC, with M = Ti, Zr and Hf. Geometrical optimization of the unit cell are in good agreement with the available experimental data. The band structures show that all three materials are conducting. The analysis of the site and momentum projected densities shows that the bonding is achieved through a hybridization of M-atom d states with S and C-atom p states. The Md-Sp bonds are lower in energy and are stiffer than Md-Cp bonds. The elastic constants are calculated using the static finite strain technique. We derived the bulk and shear moduli, Young's moduli and Poisson's ratio for ideal polycrystalline M2SC aggregates. We estimated the Debye temperature of M2SC from the average sound velocity. This is a quantitative theoretical prediction of the elastic properties of Ti2SC, Zr2SC, and Hf2SC compounds, and it still awaits experimental confirmation. 相似文献
20.
A.K.M.A. Islam F.N. Islam Abraham F. Jalbout Ludwik Adamowicz 《Solid State Communications》2006,139(6):315-320
A study of the structural, elastic and electronic properties of BeB2, a promising diboride in view of the lighter mass of Be, has been made using self-consistent Density Functional Theory (DFT). The five independent elastic constants of BeB2 are predicted for the first time. The elastic behaviour of the compound is compared with those of the superconducting MgB2 and NbB2. We also evaluate the electronic structure of BeB2 in order to obtain further insight into its surprising difference from the superconducting MgB2. 相似文献