Ab initio predictions of electronic, structural, mechanical, phonon, and optical properties of the Zr2GaC and Hf2GaC MAX phases under high pressure
Bulletin of the American Physical Society, Mar 16, 2021
Prediction study of magnetic stability, structural and electronic properties of Heusler compounds Mn$$_{2}$$PtZ (Z $$ = $$ V, Co): DFT$$+$$U$$+$$TB-mBJ calculation
The electronic structure, structural stability, mechanical, phonon, and optical properties of Zr2... more The electronic structure, structural stability, mechanical, phonon, and optical properties of Zr2GaC and Hf2GaC MAX phases have been investigated under high pressure using first-principles calculations. Formation enthalpy of competing phases, elastic constants, and phonon calculations revealed that both compounds are thermodynamically, mechanically, and dynamically stable under pressure. The compressibility of Zr2GaC is higher than that of Hf2GaC along the c-axis, and pressure enhanced the resistance to deformation. The electronic structure calculations reveal that M2GaC is metallic in nature, and the metallicity of Zr2GaC increased more than that of Hf2GaC at higher pressure. The mechanical properties, including elastic constants, elastic moduli, Vickers hardness, Poisson’s ratio anisotropy index, and Debye temperature, are reported with fundamental insights. The elastic constants C11 and C33 increase rapidly compared with other elastic constants with an increase in pressure, and t...
Theoretical predictive screening of noble-metal-containing M3AuC2 (M = Ti, V, and Cr) MAX phases
Computational Materials Science, 2022
(111), (001), and (110) surface effects on the stability and electronic-magnetic properties of Mn3P alloy
Physica E: Low-dimensional Systems and Nanostructures, 2021
A B S T R A C T In this theoretical study, we predict the (111), (001), and (110) Mn3P compounds ... more A B S T R A C T In this theoretical study, we predict the (111), (001), and (110) Mn3P compounds with a DO3-Type-structure. We first calculated the stability, and surface effects on the pure terminations of Mn3P (111), (001), and (110) surfaces using first-principle computations. Pure (111), (110), as well as the Mn2-(001) terminations, lose their half-metallic (HM) ferrimagnetic property, with higher spin polarisation (SP) (75%) for Mn2-(111) than for the other terminations. These terminations present metallic properties because the spin-up and spin-down pass the Fermi level (єF). The Mn1-P termination remained HM with full SP; this is because of the strong coupling between the surface and subsurface, which indicates that this surface is a typical candidate for spin devices. The spin magnetic moments (SMMs) were investigated in all surface states. The SMM values of the central layers of the (111), (001), and (110) terminations were similar to those in the bulk, while the SMMs in the surface layer were higher than those in the bulk Mn3P.
Ab-initio predictions of phase stability, electronic structure, and optical properties of (0001)-MAX surfaces in M2AC (M = Cr, Zr, Hf; A = Al, Ga)
Journal of Physics and Chemistry of Solids, 2022
Abstract Here, we report MAX phases' surface properties, which are essential for thin-film te... more Abstract Here, we report MAX phases' surface properties, which are essential for thin-film technology due to their excellent resistance to high-temperature oxidation, corrosion, and wear. The surface stability, electronic, and optical properties of 0001-surfaces in M2AC (M = Zr, Hf, Cr; A = Al, Ga) are investigated and compared with their bulk counterparts. The interplay between chemical bonding and charge distribution is discussed from electronic structure, including the Fermi surfaces. Four possible (0001)-terminated surfaces are considered by breaking M − C and M-A bonds in which cleavage energy of M − C is higher than M-A. The Cr–Al bond in Cr2AlC is stronger than other M-A bonds. The charge density of valance A-p electrons redistributes in the surface area, distinct from that of the bulk. The A- and M(C)-terminated (0001)-surfaces are the most stable and energetically favorable terminations due to lower surface energies. The optical properties of the most stable (0001)-surfaces were also investigated to understand the dielectric and photoconductive behavior in the (0001)-terminated surfaces of M2AC.
In the framework of density functional theory (DFT), we investigate the structural deformation, a... more In the framework of density functional theory (DFT), we investigate the structural deformation, and mechanical behavior of the Janus CrSSe, which has out-of-plane structural asymmetry, with conventional transition metal dichalcogenides (TMDs) CrS2 and CrSe2 . The Janus CrSSe could be a potential candidate for machinable optoelectronic and piezoelectric applications. We predict that these compounds are chemically, mechanically, and dynamically stable with the covalent bond between the TM(Cr) and chalcogen(X=S, Se) atoms. Due to the influence of tensile strain, the Cr-X bond length of each monolayers increases, and the thickness decreases. Interestingly, the in-plane stiffness, shear and layer moduli, Poisson’s ratio, ultimate bi/uni-axial stress of Janus CrSSe are in between the values of CrS2 and CrSe2 monolayers. Similar to TMDs, the orientation-dependent in-plane stiffness and Poisson’s ratio demonstrate the isotropic behavior in Janus CrSSe. Furthermore, it can sustain a larger v...
Ab initio predictions of stability, half-metallicity and magnetism in Co2NbAl and Co2ZrAl full-Heusler alloys
Vacuum, 2021
Abstract This paper reports ab initio computed results of stability, phonon, electronic, magnetic... more Abstract This paper reports ab initio computed results of stability, phonon, electronic, magnetic, and surface properties of Co2NbAl and Co2ZrAl full-Heusler alloys. These alloys are stable, which is confirmed by formation energy, cohesive energy, and phonon spectra. The total magnetic moments of these alloys follow the Slater-Pauling (SP) rule (Mt = Zt-24). The Nb (111) and Al (111)-terminations of Co2NbAl show half-metallic characteristic, while other terminations are metallic due to the majority density of states (DOS) and the minority DOS at the Fermi level. CoCrNbAl and CoCrZrAl show half-metallicity while CoMnZrAl and CoFeNbAl exhibit metallic nature after the substitution of Cr, Mn, and Fe atom in Co2NbAl and Co2ZrAl, respectively. The electronic structures exhibit the band gaps of 0.39 eV, 0.24 eV, and 1.19 eV for CoFeNbAl, CoCrNbAl, and CoCrZrAl, respectively. The calculated values of the magnetic moments are in good agreement with experimental data. The results confirm that Co2NbAl, Co2ZrAl, CoFeNbAl, CoCrNbAl, and CoCrZrAl can be promising alloys for spintronic devices.
Screen the half-metallic X2Y (Al/Si) full-Heusler alloys based on the first-principle calculations
Computational Materials Science, 2021
Abstract The first principle calculations investigated the structural stability, elasticity and e... more Abstract The first principle calculations investigated the structural stability, elasticity and electronic properties of 50 X2YZ full-Heusler alloys. After establishing the models, the alloys are screened by investigating stability, magnetism, and half-metallicity. For the X2YZ full-Heusler alloys, 26 alloys are stable, 24 alloys are magnetic, and 10 alloys are half-metallic. The density of states of magnetic alloys are calculated. For the alloys with half-metallicity, band structures are investigated. Our research confirms the potential application of X2YZ full-Heusler alloys.
Journal of Superconductivity and Novel Magnetism, 2017
In the original publication of the article, author name Jingchuan Zhu was incorrectly written as ... more In the original publication of the article, author name Jingchuan Zhu was incorrectly written as Zhu Jingchuan. The original article has been corrected.
Material genetic engineering studies the relationship between the composition, microstructure, an... more Material genetic engineering studies the relationship between the composition, microstructure, and properties of materials. By adjusting the atomic composition, structure, or configuration of the material and combining different processes, new materials with target properties obtained. In this paper, the design, and properties of the ordered phases in Fe25Cr25Ni25TixAl(25-x) (subscript represents the atomic percentage) multi-principal element alloys are studied. By adjusting the percentages of Ti and Al atoms, the effect of the atomic percentage content on ordered phases’ structural stability in multi-principal element alloys are studied. Thermodynamic analysis predicted the composition phase and percentage of the alloy. Formation heat, binding energy, and elastic constants confirmed the structural stability and provide a theoretical basis for designing alloys with target properties. The results showed that the disordered BCC A2 phase and the ordered BCC B2 phase are the ductile pha...
The concern for people with disabilities who are users of wheelchairs has become a dynamic resear... more The concern for people with disabilities who are users of wheelchairs has become a dynamic research area in the past several years. This research is being done to enhance the health and lifestyles of standard manual wheelchair users. As part of this research new and innovative mechanisms that give the manual wheelchair users a mechanical advantage, and allow them to operate a standard wheelchair with less effort and muscle strain are being developed. In this research, an innovative mechanism was conceived, designed, built, and tested. The path of this innovative mechanism was modeled after the semi-circular (SC) wheelchair stroke pattern. It allows the user to propel a standard wheelchair in both the push and pull strokes of the handle. This new design will allow for a more symmetric muscle development of the shoulder and upper-arm complex, and should reduce muscle (skeletal) injuries. A conceptual model of the new mechanism was formulated using SolidWorks software. Preliminary position and torque analysis were analyzed using Microsoft Excel spreadsheets. A prototype of the innovative mechanism was built and retrofitted onto a standard manual wheelchair. In addition, a portable wheelchair testing station was designed and fabricated to allow for human testing comparative measurements between a standard wheelchair and the innovative mechanism. Comparison of data from the standard wheelchair and the innovative mechanism showed energy, horsepower, and RPM ratio gains of 1.638, 1.631, and 1.64. Therefore, the mechanism shows promise to enhance the quality of life for mobility impaired citizens.
The novel ternary carbides and nitrides, known as MAX phase materials with remarkable combined me... more The novel ternary carbides and nitrides, known as MAX phase materials with remarkable combined metallic and ceramic properties, offer various engineering and technological applications. Using ab initio calculations based on generalized gradient approximation (GGA), local density approximation (LDA), and the quasiharmonic Debye model; the electronic, structural, elastic, mechanical, and thermodynamic properties of the M2GaC (M = Zr, Hf) MAX phase were investigated. The optimized lattice parameters give the first reference to the upcoming theocratical and experimental studies, while the calculated elastic constants are in excellent agreement with the available data. Moreover, obtained elastic constants revealed that both the Zr2GaC and Hf2GaC MAX phases are brittle. The band structure and density of states analysis showed that these MAX phases are electrical conductors, having strong directional bonding between M-C (M = Zr, Hf) atoms due to M-d and C-p hybridization. Formation and coh...
Half‐metallicity, magnetism, mechanical, thermal, and phonon properties of FeCrTe and FeCrSe half‐Heusler alloys under pressure
International Journal of Quantum Chemistry, 2020
The influence of pressure on half-metallicity, magnetism and thermomechanical properties of Fe-based Heusler alloys
Authorea
The half-metallicity of Heusler alloy is quite sensitive to high pressure and disorder. Therefore... more The half-metallicity of Heusler alloy is quite sensitive to high pressure and disorder. Therefore, we systematically studied the half-metallic nature, magnetism and thermomechanical properties of FeCrTe and FeCrSe Heusler alloys under high pressure using ab initio calculations based on density functional theory (DFT). The ground state lattice constants for FeCrTe and FeCrSe alloys are 5.93 and 5.57 A, consistent with available theoretical results. The formation energy, cohesive energy and elastic constant confirmed the thermodynamically and mechanical stability of both compounds. The FeCrTe and FeCrSe alloys showed half-metallic character with the band gap of 0.68 and 0.58 eV at 0 Gpa pressure respectively and magnetic moments of 2.01 µB for both alloys using GGA approximation. The elastic properties have been scrutinized and found that FeCrTe is ductile and FeCrSe is brittle at 0 Gpa pressure. Under pressure, FeCrSe turn into brittle above 10 Gpa pressure. Moreover, the average sound velocity Vm, Debye temperature ƟD and heat capacity CV were predicted under pressure. These outcomes would advantage in integrating Fe-based half-Heusler alloys in spintronic devices.
Heusler alloys with Mn and Co have been found to exhibit interesting electronic and magnetic prop... more Heusler alloys with Mn and Co have been found to exhibit interesting electronic and magnetic properties. Mn 2 CoAl is well known SGS compound while Mn 2 CoGa has weak half metallic character. By using plane wave pseudo-potential method, we studied the effect of Fe and Cr doping on half-metalicity and magnetism of these compounds. The doping destroys the SGS nature of Mn 2 CoAl while the small-scale doping enhance the half-metallicity of Mn 2 CoGa making it perfect half-metal. In case of Mn 2 CoAl, the doping decrease the band gap while increase in band width is noticed for Mn 2 CoGa. The half-metallicity is destroyed in both cases when the doping level is beyond certain degree. Moreover, we have also computed magnetic behavior of Mn 2 CoZ alloys and we found that total magnetic moments of dopped samples have higher values than that of pristine compounds.
The femur is the largest and strongest bone in the body and the structure of its proximal portion... more The femur is the largest and strongest bone in the body and the structure of its proximal portion allows the leg to move in three dimensions relative to the torso, thus serving as a linchpin of human mobility. Moreover, age related and pediatric disorders at this skeletal site are common and confer strong risk factors for current and future disability. The femur forms the skeleton of the thigh, carries body weight, supports the movements of leg and provides attachment to the muscles. Morphology of bones is very much affected by race, sex, environmental factors and life style. Materials and Methods: For this study total 285 Femurs of various bodies in central Gujarat were collected randomly and unknown age & sex. 285 Femurs were studied in department of Anatomy, Sri B.K.Shah Medical institute & Research Centre. The following measurements were measured Neck shaft angle, Femoral Length and Neck Length of femur. Results and Conlusion: Total mean length of femur was 435.8 ± 27.32 (Mean ± SD ) mm. Right side mean length of femur was 436.2 ± 27.91 (Mean ± SD ) mm. Left side mean length of femur was 433.8 ± 26.14 (Mean ± SD ) mm. Maximum length of femur was 446 mm and minimum length was 423 mm.
Theoretical Study of Structural, Magnetic, Elastic, Phonon, and Thermodynamic Properties of Heusler Alloys Fe2CrX (X = Al, Ga)
Journal of Superconductivity and Novel Magnetism, 2017
First-principle calculations based on generalized gradient approximation and quasi-harmonic Debye... more First-principle calculations based on generalized gradient approximation and quasi-harmonic Debye model were executed to analyze the structural, magnetic, elastic, phonon, and thermodynamic properties of Fe2CrX (X = Al, Ga) Heusler alloys. The computed lattice parameters concurred well with available experimental and theoretical data. The calculated elastic constants reveal that the Fe2CrAl is brittle and Fe2CrGa is ductile. The phonon dispersion relation of Fe2CrX (X = Al, Ga) are calculated using finite displacement method with a cutoff radius of 5 Å. We likewise explored the thermodynamic properties by utilizing quasi-harmonic Debye model in which bulk modulus, heat capacity, Debye temperature, Grüneisen parameter, and thermal expansion coefficient are resolved at 0–30 Gpa pressure and 0–900 K temperature from the non-equilibrium Gibbs functions.
Theoretical Study of Mechanical Stability and Physical Properties of Co2V1−xZrxGa
Journal of Superconductivity and Novel Magnetism, 2018
The mechanical stability and physical properties of Co2V1−xZrxGa (x = 0, 0.25, 0.50, 0.75, 1) hav... more The mechanical stability and physical properties of Co2V1−xZrxGa (x = 0, 0.25, 0.50, 0.75, 1) have been predicted by using ab initio calculations based on density functional theory. The exchange-correlation potentials are treated within the generalized gradient approximation-Perdew-Burke and Ernzerhhof (GGA-PBE) and Hubbard coefficient (GGA+U). The investigated minimum lattice parameter of Co2VGa is 5.8030 Å, which is in excellent agreement with available experimental and theoretical data and for Co2V1−xZrxGa (x = 0.25, 0.50, 0.75, 1) are 5.9026, 5.9625, 6.0060 and 6.0021 Å, respectively, which are predicted for the very first time. The total magnetic moments decrease with increasing concentration of x in Co2V1−xZrxGa, in agreement with the Slater-Pauling rule. Band structure and density of states calculations show that the minority spin channel exhibits band gaps of 0.43, 0.46, 0.52, 0.54 and 1.01 eV for GGA+U scheme around the Fermi level confirming that all the studied composites are half-metallic in nature. In this study, we also studied the elastic constant and it is established that all the materials are mechanically stable and ductile in nature. The Co2VGa is stiffer than other materials and all the studied composites have anisotropic behaviour. Moreover, by using a quasi-harmonic Debye model and calculated elastic constant, the Debye temperature and temperature-dependent constant volume heat capacity have been investigated.
Investigation of half-metallicity and magnetism of bulk and (111)-surfaces of Fe2MnP full Heusler alloy
Vacuum, 2019
Abstract The structural, electronic, magnetic, elastic and phonon properties of bulk and electron... more Abstract The structural, electronic, magnetic, elastic and phonon properties of bulk and electronic and magnetic properties of (111)-surfaces of AlCu2Mn-type Fe2MnP Heusler alloy have been investigated by using density functional theory based on the generalized gradient approximation scheme. The cohesive energy confirmed the stability of the alloy considered at an equilibrium lattice constant of 5.5628 A. We observed a half-metallic nature in the bulk alloy with energy band gaps of 0.34 eV and spin-flip gaps of 0.09 eV with 100% spin-polarization in the minority spin electrons. The computed magnetic moments for the Fe2MnP alloy are found to be 4 μB/f.u. The investigated elastic constants, phonon dispersion and density phonon states showed that the Fe2MnP alloy is mechanically and dynamically stable. We also found that the alloy is ductile from the Poisson's and B/G ratios. The half-metallic ferromagnetic nature is preserved in the P (111)-terminated slab among all terminations with 100% spin-polarization which is a crucial property of spin devices, since it can be optimize their performance. The spin-polarization clearly decreases by nearly 75% for Fe (111) and Mn (111)-terminated slabs due to surface states located below the Fermi level. Moreover, the computed atomic magnetic moments of (111)-slabs of the Fe2MnP Heusler alloy are extremely close to the atomic bulk values.
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