Structural, elastic and dynamical properties of \hbox { YP}{1-x}\hbox {As}{x}$$ alloys from first principles calculations (original) (raw)
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Journal of Alloys and Compounds, 2010
Information on the energy band gaps, the lattice parameters and the lattice matching to available substrates is a prerequisite for many practical applications. A pseudopotential plane-wave method as implemented in the ABINIT code is used to the AsxPyN1−x−yAl quaternary alloys lattice matched to AlP substrate to predict their energy band gaps and optical properties. The range of compositions for which the alloy is lattice-matched to AlP is determined. Very good agreement is obtained between the calculated values and the available experimental data. The Debye temperature increase when the bulk modulus is enhanced. We study the variation of elastic constants, the optical phonon frequencies (ωTO and ωLO), the static and high-frequency dielectric coefficient ɛ(0) and ɛ(∞) and the dynamic effective charge Z* with P concentration (y).▶ The range of compositions for which the alloy is lattice matched to AlP is determined. ▶ We study the variation of elastic constants, the optical phonon frequencies (ωTO and ωLO), the high-frequency dielectric coefficient ɛ(∞) and the dynamic effective charge Z* with P concentration.
Materials Science in Semiconductor Processing, 2013
We report a detailed study of the compositional dependence of the structural, elastic, electronic and dynamical properties of the In 1ÀxÀy Al x Ga y P quaternary alloys matched to AlP using pseudo-potential plane-wave method based on the density functional theory. The reliability and accuracy of the predicted physical properties mentioned above for In 1ÀxÀy Al x Ga y P=AlP are tested by comparing the calculated lattice constant, elastic constants and phonon dispersion curves for the binary AlP with the available experimental and theoretical data in the literature.
Computational Materials Science, 2010
The structural, elastic, electronic, optical and thermodynamic properties of the perovskite chloride CsCdCl 3 were investigated using the pseudo-potential plane wave (PP-PW) within the Generalized Gradient Approximation (GGA) and Local Density Approximation (LDA). The computed lattice parameter agrees well with experimental and previous theoretical works. Based on the elastic constants and their related parameters, the crystal rigidity and mechanical stability have been discussed. Energy band structure shows that the investigated material is -R indirect energy band gap semiconductor. The static dielectric constant and static refractive index are indeed, proportional to the fundamental indirect band gap. The thermal effect on the lattice parameter, bulk modulus, volume expansion coefficient, Grüneisen parameter, heat capacities and Debye temperature were predicted using the quasi-harmonic Debye model. To the best of the authors' knowledge, most of the studied properties are reported for the first time.
Vibrational Properties of Cubic AlxGa1?xN and InxGa1?xN Ternary Alloys
physica status solidi (b), 2002
The phonon dispersion curves and phonon density of states of the cubic Al x Ga 1Àx N and In x Ga 1Àx N alloys were calculated within the framework of a valence force field method and an effective charge approach for the long-range Coulomb interaction. The valence-force parameters and effective charges for the cubic GaN, AlN and InN binary compounds were fitted to the phonon frequencies at high-symmetry points in the Brillouin zone measured by Raman spectroscopy and calculated by ab initio methods. The scaling factor approximation was used to obtain the valenceforce parameters and effective charges for the alloys. A good agreement between our calculations and recent Raman data for the alloys is achieved.
Ab Initio Calculations Study of Structural and Electronic Properties of Ternary Alloy AlxIn1–xAs
Materials Sciences and Applications, 2012
First principles calculations of the structural and electronic properties of AlAs, InAs and their alloy Al x In 1−x As have been performed using the full-potential linear muffin-tin orbital (FP-LMTO) [1] method within density functional theory (DFT) [2,3]. We used the local density approximation (LDA) [4] within the generalized gradient correction (GGA) [5] to calculate the electronic structure at equilibrium volume. The effect of composition on lattice constants, bulk modulus and band gap were investigated. Deviations of the lattice constants from Vegard's law and the bulk modulus were observed for this alloy. The microscopic origins of the gap bowing were explained by using the approach of Zunger and co-workers [6-9].
Ab initio calculation of the elastic properties and the lattice dynamics of the AgBr1−xClx alloy
Computational Materials Science, 2009
The lattice dynamics and elastic properties of the ternary AgBr 1Àx Cl x alloy have been studied using firstprinciples calculations. These are done using the density-functional perturbation theory (DFPT) and employing the virtual-crystal approximation (VCA). We study the variation of the optical phonon frequencies (x TO and x LO ) and of the acoustical phonon frequencies (x TA and x LA ), the high-frequency dielectric coefficient (e 1 ), the dynamic effective charge (Z * ) and the elastic constants (C 11 , C 12 , C 44 )a sa function of the composition (x). We find that the phonon frequencies as well as the elastic constants follow a quadratic law in x and agree well with the available experimental results. The elastic constant tensors for simple cubic 8-atom supercells with x = 0.25, 0.5 and 0.75 have been computed and are in good agreement with those obtained from VCA and experiments.
Physica scripta , 2024
For the first time, the composition dependence of pentanary AlInPSbAs alloy is described. The effect of composition on the polarity (μp),mechanical parameters have been calculated for the AlxIn1-xPySbzAs1-y-z alloy. The impact of composition on the internal strain parameter (z ), bondbending force constant (α), bond-stretching force constant (β), and sound velocity (v) has been reported. Results from experiments and the investigated properties of the new alloy show a high degree of agreement. In this work, the density function theory (DFT) and the empirical pseudo-potential approach (EPM) with the virtual crystal approximation (VCA) have been used. The outcomes are expected to be used in optoelectronic applications and in understanding the mechanical properties of AlxIn1-xPySbzAs1-y-z alloy.
Procedia Structural Integrity, 2018
During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data. Abstract One of the recent trends in materials science and technology is the research of the behavior of the materials under the extreme conditions both on the theoretical and experimental basis. There are limitations of the experimental methods, however, theoretical approach can be used as a supplement to the experimental results. As a consequence, in the last two decades a vast number of structure prediction calculations have been performed on chemical systems, focusing on the high-pressure and high temperature phases. In this work, we would like to present several computational studies and their connection to the actual synthesis routes: lead sulfide (PbS), barium sulfide (BaS), and aluminum nitride (AlN). The investigated compounds were calculated on ab initio level using the most advanced tools in quantum chemistry and computational material science including Hartree-Fock Theory, Density Functional Theory (DFT) and Hybrid (B3LYP) Approximation. Their structural, mechanical, elastic and vibrational properties have been investigated and in addition, we show structure candidates as the function of size, pressure and temperature and not previously observed in any of the investigated materials thus creating new possibilities for synthesis of advanced materials with improved physical, chemical, and/or mechanical properties. Abstract One of the recent trends in materials science and technology is the research of the behavior of the materials under the extreme conditions both on the theoretical and experimental basis. There are limitations of the experimental methods, however, theoretical approach can be used as a supplement to the experimental results. As a consequence, in the last two decades a vast number of structure prediction calculations have been performed on chemical systems, focusing on the high-pressure and high temperature phases. In this work, we would like to present several computational studies and their connection to the actual synthesis routes: lead sulfide (PbS), barium sulfide (BaS), and aluminum nitride (AlN). The investigated compounds were calculated on ab initio level using the most advanced tools in quantum chemistry and computational material science including Hartree-Fock Theory, Density Functional Theory (DFT) and Hybrid (B3LYP) Approximation. Their structural, mechanical, elastic and vibrational properties have been investigated and in addition, we show structure candidates as the function of size, pressure and temperature and not previously observed in any of the investigated materials thus creating new possibilities for synthesis of advanced materials with improved physical, chemical, and/or mechanical properties.
High Pressure Research, 2011
The lattice dynamics and elastic properties of the ternary AgBr 1Àx Cl x alloy have been studied using firstprinciples calculations. These are done using the density-functional perturbation theory (DFPT) and employing the virtual-crystal approximation (VCA). We study the variation of the optical phonon frequencies (x TO and x LO ) and of the acoustical phonon frequencies (x TA and x LA ), the high-frequency dielectric coefficient (e 1 ), the dynamic effective charge (Z * ) and the elastic constants (C 11 , C 12 , C 44 ) as a function of the composition (x). We find that the phonon frequencies as well as the elastic constants follow a quadratic law in x and agree well with the available experimental results. The elastic constant tensors for simple cubic 8-atom supercells with x = 0.25, 0.5 and 0.75 have been computed and are in good agreement with those obtained from VCA and experiments.