排序方式: 共有63条查询结果,搜索用时 46 毫秒
41.
The elastic, electronic, magnetic and optical properties of filled skutterudite ROs4P12 (R = Sm, Eu and Gd) have been studied by first principles calculation. The full-potential linearized augmented plane wave method based on density functional theory was employed. For the exchange-correlation potential, local spin density approximation + Coulomb repulsion (LSDA + U) is used to treat the f-electrons more effectively. The numerical values of the elastic parameters are estimated in the framework of the Voigt–Reuss–Hill approximation. OsP-based filled skutterudite with localized 4f and 5d-electrons shows dense energy bands near Fermi energy originating from rare earth and Os atoms. The dense density of states near EF reveals that these compounds are suitable for thermoelectric application. Optical constants including dielectric function, optical reflectivity and refractive index are calculated for photon energy radiation up to 12 eV. The exchange-splitting of R-4f states were analyzed to explain the ferromagnetic behavior of ROs4P12. 相似文献
42.
M. Hachemaoui R. Khenata A. Bouhemadou S. Bin-Omran Ali H. Reshak F. Semari D. Rached 《Solid State Communications》2010,150(39-40):1869-1873
We have performed accurate ab initio total energy calculations using the full-potential linear augmented plane wave plus local orbitals method with the local density approximation for the exchange–correlation potential to investigate the systematic trends for structural and elastic properties of the cubic LaFe4A12 skutterudites’ family depending on the type of A pnicogen atom (A stands for P, As and Sb). The calculated equilibrium lattice constants and internal free parameters are in good agreement with the experimental results. For the first time, the numerical estimates of the independent elastic constants and their pressure dependence are performed using the total energy variation as function of strain technique. Isotropic elastic parameters and related properties, namely bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, Lamé’s coefficients, average sound velocity and Debye temperature, are estimated in the framework of the Voigt–Reuss–Hill approximation for ideal polycrystalline LaFe4A12 aggregates. 相似文献
43.
M. Rabah D. Rached R. Khenata N. Moulay 《Journal of Physics and Chemistry of Solids》2008,69(11):2907-2910
We report local density-functional calculations using the full-potential linearized muffin-tin orbital method (FP-LMTO) for platinum carbide (PtC) in the, rock-salt (B1), zinc-blende (B3), wurtzite (B4), nickel-arsenide (B8) and PbO (B10) structures. The ground state properties such as the equilibrium lattice constant, elastic constants, the bulk modulus and its pressure derivative of PtC in these phases are determined and compared with available experimental and theoretical data.Our calculations show that the ground state phase of PtC to be zinc-blende (B3) structure at zero pressure and the nickel-arsenide (B8) structure is a high-pressure phase. The transition pressures at which this compound undergoes the structural phase transition from (B3) to (B8) and from (B3) to (B1) are found to be 34.25 and 51.28 GPa, respectively. The highest bulk modulus values in the nickel-arsenide (B8), zinc-blende (B3), rock-salt (B1) and PbO (B10) structures indicate that PtC is a hard material. 相似文献
44.
M. Hichour D. Rached M. Rabah S. Benalia R. Khenata F. Semari 《Physica B: Condensed Matter》2009,404(21):4034-4038
First-principle calculations of structural, elastic and high pressure properties of antiperovskites XNBa3 (X=As, Sb) are performed, using the full-potential linear muffin-tin orbital (FP-LMTO) method. The local density approximation (LDA) is used for the exchange-correlation (XC) potential. Results are given for lattice constant, bulk modulus and its pressure derivatives. We have determined the elastic constants C11, C12 and C44 and their pressure dependence. We derived shear moduli, Young's modulus, Poisson's ratio and Lamé's constants for ideal polycrystalline XNBa3 aggregates. By analyzing the ratio of the bulk to shear moduli, we conclude that XNBa3 compounds are brittle in nature. We estimated the Debye temperature of XNBa3 from the average sound velocity. This is the first quantitative theoretical prediction of the elastic properties of AsNBa3 and SbNBa3 compounds, and it still awaits experimental confirmation. 相似文献
45.
M.?SahnounEmail author C.?Daul R.?Khenata H.?Baltache 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,45(4):455-458
We present first-principles calculations for the
optical properties of germanium dioxide in the rutile structure.
The electronic band structure has been calculated
self-consistently within the local density approximation using the
full-potential linearized augmented plane wave method. The
electronic band structure shows that the fundamental energy gap is
direct at the center of the Brillouin zone. The determinant role
of a band structure computation with respect to the analysis of
the optical properties is discussed. 相似文献
46.
We report a systematic study of the structural, electronic, optical and elastic properties of the ternary ruthenium-based hydrides A2RuH6 (A = Mg, Ca, Sr and Ba) within two complementary first-principles approaches. We describe the properties of the A2RuH6 systems looking for trends on different properties as a function of the A sublattice. Our results are in agreement with experimental ones when the latter are available. In particular, our theoretical lattice parameters obtained using the GGA-PBEsol to include the exchange-correlation functional are in good agreement with experiment. Analysis of the calculated electronic band structure diagrams suggests that these hydrides are wide nearly direct band semiconductors, with a very slight deviation from the ideal direct-band gap behaviour and they are expected to have a poor hole-type electrical conductivity. The TB-mBJ potential has been used to correct the deficiency of the standard GGA for predicting the optoelectronic properties. The calculated TB-mBJ fundamental band gaps are about 3.53, 3.11, 2.99 and 2.68 eV for Mg2RuH6, Ca2RuH6, Sr2RuH6 and Ba2RuH6, respectively. Calculated density of states spectra demonstrates that the topmost valence bands consist of d orbitals of the Ru atoms, classifying these materials as d-type hydrides. Analysis of charge density maps tells that these systems can be classified as mixed ionic-covalent bonding materials. Optical spectra in a wide energy range from 0 to 30 eV have been provided and the origin of the observed peaks and structures has been assigned. Optical spectra in the visible range of solar spectrum suggest these hydrides for use as antireflection coatings. The single-crystal and polycrystalline elastic moduli and their related properties have been numerically estimated and analysed for the first time. 相似文献
47.
Band-gap engineering of La_(1-x)Nd_xAlO_3(x = 0,0.25,0.50,0.75,1)perovskite using density functional theory:A modified Becke Johnson potential study
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sandeep D P Rai A Shankar M P Ghimire Anup Pradhan Sakhya T P Sinha R Khenata S Bin Omran R K Thapa 《中国物理 B》2016,25(6):67101-067101
The structural,electronic,and magnetic properties of the Nd-doped Rare earth aluminate,La_(1-x)Nd_xAlO_3(x = 0%to 100%) alloys are studied using the full potential linearized augmented plane wave(FP-LAPW) method within the density functional theory.The effects of the Nd substitution in La AlO_3 are studied using the supercell calculations.The computed electronic structure with the modified Becke–Johnson(m BJ) potential based approximation indicates that the La_(1-x)Nd_xAlO_3 alloys may possess half-metallic(HM) behaviors when doped with Nd of a finite density of states at the Fermi level(E_F).The direct and indirect band gaps are studied each as a function of x which is the concentration of Nddoped La AlO_3.The calculated magnetic moments in the La_(1-x)Nd_xAlO_3 alloys are found to arise mainly from the Nd-4f state.A probable half-metallic nature is suggested for each of these systems with supportive integral magnetic moments and highly spin-polarized electronic structures in these doped systems at E_F.The observed decrease of the band gap with the increase in the concentration of Nd doping in La AlO_3 is a suitable technique for harnessing useful spintronic and magnetic devices. 相似文献
48.
ABSTRACTFirst-principles total energy calculations have been performed using the full potential linearised augmented plane wave (FP-LAPW) method as implemented in the WIEN2k code based on the density functional theory (DFT) to investigate the Al-doping effects on the structural, electronic and optical properties of AlxIn1-xP ternary alloys in the zinc-blende (ZB) phase. Different approximations of exchange-correlations energy were used such as the local density approximation (LDA), the generalised gradient approximation within parameterisation of Perdew–Burke–Ernzerhof (PBE-GGA), and the Wu-Cohen (WC-GGA). In addition, we have calculated the band structures with high accuracy using the Tran-Blaha modified Becke–Johnson (TB-mBJ) approach. The pressure dependence of the electronic and optical properties of binary AlP, InP compounds and their related ternary alloys AlxIn1-xP were also investigated under hydrostatic pressure for (P?=?0.0, 5.0,10.0, 15.0, 20.0, 25.0?GPa), where it is found that InP compound change from direct to indirect band gap for P?≥?9.16?GPa. Furthermore, we have calculated the thermodynamic properties of InP and AlP binary compounds as well as the AlxIn1-xP solid solutions, where the quasi-harmonic Debye model has been employed to predict the pressure and temperature dependent Gibbs free energy, heat capacity, Debye temperature and entropy. 相似文献
49.
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
50.
T.?Ouahrani A. H.?Reshak A.?Otero de la Roza M.?Mebrouki V.?Lua?a R.?Khenata B.?Amrani 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,72(3):361-366
Epitaxial magnetic oxide films can be reversibly strained on piezoelectric
monocrystalline substrates of
Pb(Mg1/3Nb2/3)0.72Ti0.28O3(PMN-PT). The magnetic
film/piezoelectric substrate sample that undergoes well-defined biaxial,
nearly linear strains exceeding 0.1% provides a model system for the
inspection of strain-dependent magnetic properties which are exploited in
many two-phase magnetoelectric multiferroics. We review the properties of
the applied pseudocubic PMN-PT(001) substrates, and summarize results for
the strain-dependent magnetization of ferromagnetic manganites
(La, A)MnO3 (A = Sr or Ca). 相似文献