scholarly journals Physical Properties of XN (X = B, Al, Ga, In) in the Pm−3n phase: First-Principles Calculations

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1280 ◽  
Author(s):  
Qidong Zhang ◽  
Yucong Zou ◽  
Qingyang Fan ◽  
Yintang Yang
Keyword(s):  
Shear Modulus ◽  
Poisson’S Ratio ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Poisson's Ratio ◽  
First Principles Calculations ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Debye Temperatures ◽  
Direct Band

Three direct semiconductor materials and one indirect semiconductor material, Pm−3n XN (X = B, Al, Ga, In), are investigated in our work, employing density functional theory (DFT), where the structural properties, stability, elastic properties, elastic anisotropy properties and electronic properties are included. The shear modulus G and bulk modulus B of Pm−3n BN are 290 GPa and 244 GPa, respectively, which are slightly less than the values of B and G for c-BN and Pnma BN, while they are larger than those of C64 in the I41/amd phase. The shear modulus of Pm−3n BN is the greatest, and the shear modulus of C64 in the I41/amd phase is the smallest. The Debye temperatures of BN, AlN, GaN and InN are 1571, 793, 515 and 242 K, respectively, using the elastic modulus formula. AlN has the largest anisotropy in the Young’s modulus, shear modulus, and Poisson‘s ratio; BN has the smallest elastic anisotropy in G; and InN has the smallest elastic anisotropy in the Poisson’s ratio. Pm−3n BN, AlN, GaN and InN have the smallest elastic anisotropy along the (111) direction, and the elastic anisotropy of the E in the (100) (010) (001) planes and in the (011) (101) (110) planes is the same. The shear modulus and Poisson’s ratio of BN, AlN, GaN and InN in the Pm−3n phase in the (001), (010), (100), (111), (101), (110), and (011) planes are the same. In addition, AlN, GaN and InN all have direct band-gaps and can be used as a semiconductor within the HSE06 hybrid functional.

scholarly journals ELASTIC PROPERTIES OF TRANSITION METAL DIOXIDES: XO2 (X = Ru, Rh, Os, andIr)

2008 ◽  
Vol 19 (08) ◽  
pp. 1269-1275 ◽  
Author(s):  
YANLING LI ◽  
ZHI ZENG
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Shear Modulus ◽  
Elastic Properties ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Debye Temperatures ◽  
Metal Dioxides

The elastic properties of rutile transition metal dioxides XO2 ( X = Ru , Rh , Os , and Ir ) are investigated using first-principles calculations based on density functional theory. Elastic constants, bulk modulus, shear modulus, and Young's modulus as well as Possion ratio are given. OsO 2 and IrO 2 show strong incompressibility. The hardness estimated for these dioxides shows that they are not superhard solids. The obtained Debye temperatures are comparative to those of transition metal dinitrides or diborides.

scholarly journals First principles calculations on theoretical band gap improvement of IIIA-VA zinc-blende semiconductor InAs

2020 ◽  
Vol 31 (12) ◽  
pp. 2050178
Author(s):  
Waqas Mahmood ◽  
Arfan Bukhtiar ◽  
Muhammad Haroon ◽  
Bing Dong
Keyword(s):  
Band Gap ◽  
Density Functional ◽  
Local Density ◽  
Lattice Parameter ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Zinc Blende ◽  
Valence States ◽  
Direct Band ◽  
Experimental Findings

The structural, electronic, dielectric and vibrational properties of zinc-blende (ZB) InAs were studied within the framework of density functional theory (DFT) by employing local density approximation and norm-conserving pseudopotentials. The optimal lattice parameter, direct band gap, static dielectric constant, phonon frequencies and Born effective charges calculated by treating In-4d electrons as valence states are in satisfactory agreement with other reported theoretical and experimental findings. The calculated band gap is reasonably accurate and improved in comparison to other findings. This work will be useful for more computational studies related to semiconductor devices.

scholarly journals Novel III-V Nitride Polymorphs in the P42/mnm and Pbca Phases

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3743 ◽  
Author(s):  
Qingyang Fan ◽  
Xin Ai ◽  
Junni Zhou ◽  
Xinhai Yu ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Band Gap ◽  
Density Functional ◽  
Mechanical Stability ◽  
Elastic Anisotropy ◽  
Wide Band ◽  
Light Emitting ◽  
Ultraviolet Detectors ◽  
Direct Band

In this work, the elastic anisotropy, mechanical stability, and electronic properties for P42/mnm XN (XN = BN, AlN, GaN, and InN) and Pbca XN are researched based on density functional theory. Here, the XN in the P42/mnm and Pbca phases have a mechanic stability and dynamic stability. Compared with the Pnma phase and Pm-3n phase, the P42/mnm and Pbca phases have greater values of bulk modulus and shear modulus. The ratio of the bulk modulus (B), shear modulus (G), and Poisson’s ratio (v) of XN in the P42/mnm and Pbca phases are smaller than those for Pnma XN and Pm-3n XN, and larger than those for c-XN, indicating that Pnma XN and Pm-3n XN are more ductile than P42/mnm XN and Pbca XN, and that c-XN is more brittle than P42/mnm XN and Pbca XN. In addition, in the Pbca phases, XN can be considered a semiconductor material, while in the P42/mnm phase, GaN and InN have direct band-gap, and BN and AlN are indirect wide band gap materials. The novel III-V nitride polymorphs in the P42/mnm and Pbca phases may have great potential for application in visible light detectors, ultraviolet detectors, infrared detectors, and light-emitting diodes.

First-Principles Study of the Elastic Properties of Hexagonal Phase ScAx (A=H, He)

2013 ◽  
Vol 690-693 ◽  
pp. 1723-1727
Author(s):  
Kai Min Fan ◽  
Li Yang ◽  
Jing Tang ◽  
Qing Qiang Sun ◽  
Xiao Tao Zu
Keyword(s):  
Elastic Modulus ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
First Principles ◽  
Poisson’S Ratio ◽  
Hexagonal Phase ◽  
Poisson's Ratio ◽  
First Principles Calculations ◽  
Charge Densities ◽  
Change Mechanism

First-principles calculations are performed to investigate the Young’s modulus, bulk modulus, shear modulus and Poisson’s ratio of hexagonal phase ScAx(A=H, He), where x=0, 0.0313, 0.125 and 0.25, represent the ratio of interstitial atoms A (A=H, He) to Sc atoms. The influences of hydrogen concentrations and helium concentrations on elastic modulus and Poisson’s ratio of ScAx(A=H, He) have been studied. The results indicate that hydrogen and helium have different effects on the elastic modulus of hexagonal phase scandium. The change mechanism of the Poisson’s ratio with the variation of the x ranging from 0 to 0.25 has also been studied in hexagonal phase ScAx(A=H, He). In addition, the changes in the charge densities of ScAxdue to the presence of hydrogen and helium have been calculated.

DFT study of SmXO3 (X = Al and Co) for elastic, mechanical and optical properties

2018 ◽  
Vol 32 (32) ◽  
pp. 1850362 ◽  
Author(s):  
A. Afaq ◽  
Abu Bakar ◽  
Sajid Anwar ◽  
Waheed Anwar ◽  
Fazal-e-Aleem
Keyword(s):  
Optical Properties ◽  
Poisson’S Ratio ◽  
Density Functional ◽  
Structural Parameters ◽  
Poisson's Ratio ◽  
Published Data ◽  
Generalized Gradient ◽  
Elastic Parameters ◽  
Functional Theory ◽  
Anisotropic Factor

The first-principles study of cubic perovskites SmXO3 (X = Al and Co) for elastic, mechanical and optical properties is done in the framework of density functional theory (DFT). Optimized structural parameters are obtained first to find mechanical and optical properties of the materials. These obtained structural parameters are in accordance with the published data. The cubic elastic parameters C[Formula: see text], C[Formula: see text] and C[Formula: see text] are then calculated by using generalized gradient approximation (GGA) as an exchange correlation functional in Kohn–Sham equations. Poisson’s ratio, shear modulus, Young’s modulus and anisotropic factor are deduced from these elastic parameters. These compounds are found to be elastically anisotropic and SmAlO3 is brittle while SmCoO3 is ductile. Their covalent nature is also discussed by using Poisson’s ratio. In addition, optical properties like absorption coefficient, extinction coefficient, energy loss function, dielectric function, refractive index, reflectivity and optical conductivity are studied. This study predicts that SmAlO3 and SmCoO3 are suitable for optoelectronic devices.

Properties of Cmc21-X2As2O (X = Si, Ge, and Sn) by First-Principles Calculations

2018 ◽  
Vol 73 (11) ◽  
pp. 1025-1035 ◽  
Author(s):  
Ruike Yang ◽  
Yucan Ma ◽  
Qun Wei ◽  
Dongyun Zhang
Keyword(s):  
Density Functional ◽  
Phonon Dispersion ◽  
Dielectric Constants ◽  
First Principles Calculations ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Narrow Bandgap ◽  
Bandgap Semiconductors ◽  
Mechanical Strengths ◽  
Static Dielectric Constants

AbstractFor the compounds Cmc21-X2As2O (X = Si, Ge, and Sn), the stabilities are verified by the elastic constants and the phonon dispersion spectra. The structural, mechanical, electronic, and optical properties are investigated by using density functional theory (DFT) calculations. For Cmc21-X2As2O, the mechanical strengths in the [100], [010], and [001] directions are studied. Young’s modulus for Cmc21-Ge2As2O is more anisotropic than that of Cmc21-Si2As2O and Cmc21-Sn2As2O. The band structures of Cmc21-Si2As2O and Cmc21-Sn2As2O show that they are indirect-bandgap semiconductors with bandgaps of 2.744 and 2.201 eV, by using the HSE06 hybrid functional. Cmc21-Ge2As2O is a direct narrow-bandgap semiconductor with a bandgap of 2.131 eV. The static dielectric constants of Cmc21-Si2As2O and Cmc21-Sn2As2O in the [001] direction are higher than those in the [100] and [010] directions. The static dielectric constant of Cmc21-Ge2As2O in the [001] direction is lower than those in the [100] and [010] directions.

Exploring the impact of hydrostatic pressure on the structural, electronic and mechanical properties of ZrNiPb half-Heusler alloy: A DFT approach

2018 ◽  
Vol 32 (23) ◽  
pp. 1850248
Author(s):  
M. I. Babalola ◽  
B. I. Adetunji ◽  
B. E. Iyorzor ◽  
A. Yaya
Keyword(s):  
Mechanical Properties ◽  
Heusler Alloy ◽  
Poisson’S Ratio ◽  
Density Functional ◽  
Energy Gap ◽  
Poisson's Ratio ◽  
Generalized Gradient ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
The Impact

The structural, electronic, elastic and mechanical properties of ZrNiPb half-Heusler alloy under pressure ranging from 0 to 25 GPa have been studied using the density functional theory within the generalized gradient approximation (GGA). The results of ambient condition were in good agreement with the available theoretical and experimental data. Our electronic structure and density of state results show that ZrNiPb is an indirect bandgap semiconductor half-Heusler alloy with a narrow energy gap of 0.375 eV. Based on the calculated elastic constants (C[Formula: see text], C[Formula: see text] and C[Formula: see text]), Young’s modulus (E), Poisson’s ratio ([Formula: see text]), Shear modulus (G), Zener anisotropy factor (A) and brittle-ductile behaviors under pressure have been discussed. The calculated Poisson’s ratio shows that ZrNiPb undergoes a relatively small volume change during uniaxial deformation. We show that the chemical bonds in ZrNiPb are stronger due to the high value of C[Formula: see text].

First-principles investigation of the electronic, mechanical, and thermodynamic properties of europium carbide

2015 ◽  
Vol 93 (4) ◽  
pp. 409-412 ◽  
Author(s):  
Wen Huang ◽  
Lijun Yang
Keyword(s):  
Thermodynamic Properties ◽  
Shear Modulus ◽  
Sound Velocity ◽  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Longitudinal Sound Velocity ◽  
Temperature Melting

The electronic, mechanical, and thermodynamic properties of europium carbide (EuC2) are investigated using first-principles density functional theory within the generalized gradient approximation. The calculated elastic constants indicate that EuC2 is mechanically stable. The shear modulus, Young’s modulus, Poisson’s ratio, the bulk modulus – shear modulus ratio, shear anisotropy, and elastic anisotropy are also calculated. Finally, we obtain the Vickers hardness, averaged sound velocity, longitudinal sound velocity, transverse sound velocity, Debye temperature, melting point, and thermal conductivity of EuC2.

scholarly journals Optical, Electronic Properties and Anisotropy in Mechanical Properties of “X” Type Carbon Allotropes

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2079 ◽  
Author(s):  
Jiao Cheng ◽  
Qidong Zhang
Keyword(s):  
Shear Modulus ◽  
Sound Velocity ◽  
Young’S Modulus ◽  
Debye Temperature ◽  
Poisson’S Ratio ◽  
Carbon Materials ◽  
Elastic Anisotropy ◽  
Young's Modulus ◽  
Poisson's Ratio ◽  
Cubic Symmetry

Based on first-principle calculations, the mechanical anisotropy and the electronic and optical properties of seven kinds of carbon materials are investigated in this work. These seven materials have similar structures: they all have X-type structures, with carbon atoms or carbon clusters at the center and stacking towards the space. A calculation of anisotropy shows that the order of elastic anisotropy in terms of the shear modulus, Young’s modulus and Poisson’s ratio of these seven carbon materials with similar structure is diamond < supercubane < T carbon < Y carbon < TY carbon < cubane-diyne < cubane-yne. As these seven carbon materials exhibit cubic symmetry, Young’s modulus has the same anisotropy in some major planes, so the order of elastic anisotropy in the Young’s modulus of these seven main planes is (111) plane < (001) plane = (010) plane = (100) plane < (011) plane = (110) plane = (101) plane. It is also due to the fact that their crystal structure has cubic symmetry that the elastic anisotropy in the shear modulus and the Poisson’s ratio of these seven carbon materials on the seven major planes are the same. Among the three propagation directions of [100], [110], and [111], the [110] propagation direction’s anisotropic ratio of the sound velocity of TY carbon is the largest, while the anisotropic ratio of the sound velocity of cubane-diyne on the [100] propagation direction is the smallest. In addition, not surprisingly, the diamond has the largest Debye temperature, while the TY carbon has the smallest Debye temperature. Finally, TY carbon, T carbon and cubane-diyne are also potential semiconductor materials for photoelectric applications owing to their higher or similar absorption coefficients to GaAs in the visible region.

Direct band gap nature and optical response of BexMgyZn1−(x+y)Se

2016 ◽  
Vol 30 (03) ◽  
pp. 1650007
Author(s):  
Naeemullah ◽  
G. Murtaza ◽  
R. Khenata ◽  
S. Bin Omran
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Experimental Measurements ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Direct Band Gap ◽  
Direct Band ◽  
First Time ◽  
Ultraviolet Energy

For the first time, the electronic and optical properties of the quaternary Be[Formula: see text]Mg[Formula: see text]Zn[Formula: see text]Se alloy have been investigated using first-principles calculations within the framework of density functional theory (DFT). Variations in the direct band gap with the change in [Formula: see text] and [Formula: see text] compositions show agreement with the experimental measurements. Evaluation of the dielectric function and refractive index reveals the optical activity in the visible and ultraviolet energy regions.

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