Phase Stability, Elastic Modulus and Elastic Anisotropy of X Doped (X = Zn, Zr and Ag) Al3Li: Insight from First-Principles Calculations

In present work, the effects of alloying elements X (X = Zn, Zr and Ag) doping on the phase stability, elastic properties, anisotropy and Debye temperature of Al3Li were studied by the first-principles method. Results showed that pure and doped Al3Li can exist and be stable at 0 K. Zn and Ag elements preferentially occupy the Al sites and Zr elements tend to occupy the Li sites. All the Cij obey the mechanical stability criteria, indicating the mechanical stability of these compounds. The overall anisotropy decreases in the following order: Al23Li8Ag > Al3Li > Al23Li8Zn > Al24Li7Zr, which shows that the addition of Zn and Zr has a positive effect on reducing the anisotropy of Al3Li. The shear anisotropic factors for Zn and Zr doped Al3Li are very close to one, meaning that elastic moduli do not strongly depend on different shear planes. For pure and doped Al3Li phase, the transverse sound velocities νt1 and νt2 among the three directions are smaller than the longitudinal sound velocity νl. Moreover, only the addition of Zn is beneficial to increasing the ΘD of Al3Li among the three elements.

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First-Principles Calculations of the Mechanical and Elastic Properties of 2Hc- and 2Ha-WS2/CrS2 Under Pressure

Zeitschrift für Naturforschung A ◽

10.1515/zna-2015-0517 ◽

2016 ◽

Vol 71 (6) ◽

pp. 517-524 ◽

Cited By ~ 1

Author(s):

Hua-Long Jiang ◽

Song-Hao Jia ◽

Da-Wei Zhou ◽

Chun-Ying Pu ◽

Fei-Wu Zhang ◽

...

Keyword(s):

Shear Modulus ◽

Elastic Properties ◽

First Principles ◽

Elastic Moduli ◽

Mechanical Stability ◽

First Principles Calculations ◽

Stability Criteria ◽

Poisson Coefficient ◽

Debye Temperatures ◽

Two Phases

AbstractBy utilizing the first-principles method, the pressure-induced effects on phase transition, mechanical stability, and elastic properties of WS2/CrS2 are investigated in the pressure range from 0 to 80 GPa. Transitions from 2Hc to 2Ha for WS2 and CrS2 are found to occur at 17.5 and 25 GPa, respectively. It is found that both 2Ha and 2Hc phases of WS2 and CrS2 meet the mechanical stability criteria up to 80 GPa, suggesting that those structures are mechanically stable. The bulk and shear modulus anisotropy of the two phases of WS2 and CrS2 decrease rapidly under pressure and, finally, trend to isotropy. With increasing pressure, the elastic moduli (Y, B, and G), sound velocities (vs, vp, vm), and Debye temperatures (Θ) of 2Ha and 2Hc of WS2 and CrS2 increase monotonously. Moreover, the Debye temperature (Θ) of 2Hc phase is higher than that of 2Ha phase for both WS2 and CrS2. The bulk, shear, and Young’s modulus, Poisson coefficient, and brittle/ductile behaviour are estimated. The percentages of anisotropy in compressibility and shear and the ratio of bulk to shear modulus (B/G) are also studied.

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Structural, elastic and electronic properties of new superhard orthorhombic C28

International Journal of Modern Physics B ◽

10.1142/s0217979219502278 ◽

2019 ◽

Vol 33 (20) ◽

pp. 1950227

Author(s):

Rui Zhang ◽

Qun Wei ◽

Bing Wei ◽

Ruike Yang ◽

Ke Cheng ◽

...

Keyword(s):

Band Structure ◽

Electronic Properties ◽

Vickers Hardness ◽

First Principles ◽

Superhard Material ◽

Mechanical Stability ◽

Elastic Anisotropy ◽

First Principles Calculations ◽

Stability Criteria ◽

Imaginary Frequency

The structural, mechanical and electronic properties of recently reported superhard material C[Formula: see text] are studied by first-principles calculations. The unit cell of C[Formula: see text] is composed of 28 carbon atoms and all sp3 hybridized bonds. From 0 GPa to 100 GPa, C[Formula: see text] satisfies the mechanical stability criteria and the phonon spectrum of C[Formula: see text] has no imaginary frequency, which means that C[Formula: see text] is mechanically and dynamically stable. The results of hardness calculated show that C[Formula: see text] is a potential superhard material with the Vickers hardness of 84.0 GPa. By analyzing the elastic anisotropy, we found that elastic anisotropy of C[Formula: see text] increases with pressure. The calculations of band structure demonstrates that C[Formula: see text] is an indirect bandgap semiconductor with the gap of 4.406 eV. These analyses demonstrate C[Formula: see text] is a superhard semiconductor material.

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Structural, mechanical and thermodynamic properties study on Mg–Y alloys from first-principles calculations

International Journal of Modern Physics B ◽

10.1142/s0217979220502203 ◽

2020 ◽

Vol 34 (25) ◽

pp. 2050220

Author(s):

Yingying Chen ◽

Xilong Dou ◽

Wenjie Zhu ◽

Gang Jiang ◽

Aijie Mao

Keyword(s):

Thermodynamic Properties ◽

First Principles ◽

Mechanical Stability ◽

Elastic Anisotropy ◽

Crystal Structure Analysis ◽

First Principles Calculations ◽

Phonon Spectra ◽

Volume Entropy ◽

Ductile Behavior ◽

Searching Method

The structures with different compositions of the binary Mg–Y alloys have been predicted by first-principles calculations combined with an unbiased Crystal structure Analysis by Particle Swarm Optimization (CALYPSO) structure searching method. The two already known stoichiometries alloys of Mg1Y1 with Pm-[Formula: see text] symmetry and Mg3Y1 with Fm-[Formula: see text] are confirmed, and a new stoichiometry alloy of Mg1Y3 with [Formula: see text] symmetry is proposed. The dynamical and mechanical stabilities for the three alloys at different pressures are investigated by phonon spectra and mechanical stability criteria, respectively. Subsequently, the bulk modulus, shear modulus, Young’s modulus, the brittleness/ductile behavior, the elastic anisotropy as well as Vickers hardness for the three alloys at 0 GPa are discussed in detail. The results show that the Mg1Y1, Mg3Y1 and Mg1Y3 alloys improve the hardness and stiffness compared with pure Mg, and Mg1Y3 alloy is of the best ductility in the three alloys. Meanwhile, the three alloys exhibit anisotropic. Moreover, the thermodynamic properties, such as Debye temperature, heat capacity at constant volume, entropy and Helmholtz free energy for the three stable alloys, are predicted and discussed.

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Phase stability, elastic anisotropy and electronic structure of cubic MAl2(M = Mg, Ca, Sr and Ba) Laves phases from first-principles calculations

Materials Research Express ◽

10.1088/2053-1591/3/10/106505 ◽

2016 ◽

Vol 3 (10) ◽

pp. 106505 ◽

Cited By ~ 14

Author(s):

Yuanyuan Kong ◽

Yonghua Duan ◽

Lishi Ma ◽

Runyue Li

Keyword(s):

Electronic Structure ◽

Phase Stability ◽

First Principles ◽

Elastic Anisotropy ◽

First Principles Calculations ◽

Laves Phases

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Theoretical prediction of structural stability, elastic and magnetic properties for Mn2NiGa alloy

Modern Physics Letters B ◽

10.1142/s0217984921502316 ◽

2021 ◽

pp. 2150231

Author(s):

Jing Bai ◽

Jinlong Wang ◽

Shaofeng Shi ◽

Xinzeng Liang ◽

Yiqiao Yang ◽

...

Keyword(s):

Magnetic Properties ◽

Ground State ◽

First Principles ◽

State Energy ◽

Mechanical Stability ◽

Parent Phase ◽

First Principles Calculations ◽

Stability Criteria ◽

The Past ◽

Cubic Structure

The parent phase structure of Mn2NiGa has always been controversial in the past decade. The ground state energy of the conventional cubic structure is higher than that of the Hg2CuTi structure, while the widely accepted Hg2CuTi structure for the parent phase does not satisfy with the mechanical stability criteria. In this work, a new configuration was found by the first-principles calculations. Its total energy is lower than that of the Hg2CuTi structure. Moreover, the elastic constants of this new structure can satisfy the criteria of mechanical stability. This suggests that the newly proposed structure is more likely than Hg2CuTi-type for the parent phase of the Mn2NiGa alloys.

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Phase stability and elastic moduli of Cr2Nb by first-principles calculations

Intermetallics ◽

10.1016/s0966-9795(98)00005-3 ◽

1999 ◽

Vol 7 (1) ◽

pp. 5-9 ◽

Cited By ~ 72

Author(s):

Suklyun Hong ◽

C.L. Fu

Keyword(s):

Phase Stability ◽

First Principles ◽

Elastic Moduli ◽

First Principles Calculations

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Effects of Scandium Addition on the Structural Stability and Ideal Strengths of Magnesium-Lithium Alloys

Zeitschrift für Naturforschung A ◽

10.1515/zna-2018-0223 ◽

2018 ◽

Vol 73 (10) ◽

pp. 947-956

Author(s):

Meiguang Zhang ◽

Haiyan Yan ◽

Qun Wei

Keyword(s):

Structural Stability ◽

First Principles ◽

Elastic Moduli ◽

Elastic Anisotropy ◽

First Principles Calculations ◽

Calculated Stress ◽

Sc Addition ◽

Critical Strains ◽

Lithium Alloys ◽

Substitutional Alloys

AbstractThe effects of scandium (Sc) solute addition on the structural stability, mechanical strength, and electronic structure of magnesium-lithium (Mg-Li) ordered alloy were comprehensively studied by first-principles calculations. Two kinds of MgLi-Sc substitutional alloys (Mg-substituted Mg8−xLi8Scx and Li-substituted Mg8Li8−xScx) hold cubic lattice symmetry and become more stable with the increase in Sc content. The mechanical properties, including single crystal elastic constants, polycrystalline elastic moduli, and elastic anisotropy behaviors, have been systematically studied for two considered MgLi-Sc substitutional alloys. It was found that Mg8Li8−xScx exhibits larger elastic moduli than those of Mg8−xLi8Scx with the same Sc content; however, the derived elastic moduli of two substitutional alloys showed nonlinear variations as a function of Sc addition. Calculated stress–strain curves show an increasing of ideal tensile strengths and critical strains of the MgLi-Sc substitutional alloys along the <110> and <111> directions with Sc addition, indicating that the cubic MgLi-Sc substitutional alloy is mechanically harder and less brittle at higher Sc content. Furthermore, the developments of the electronic structures of two types of the studied alloys with increasing Sc addition were also investigated by the density of states and electronic localization function calculations.

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First-Principles Calculations of the Structure Stability and Mechanical Properties of LiFeAs and NaFeAs under Pressure

Advances in Materials Science and Engineering ◽

10.1155/2018/3219685 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Zhengquan Hu ◽

Weiwei Xu ◽

Cai Chen ◽

Yufeng Wen ◽

Lili Liu

Keyword(s):

First Principles ◽

Pressure Range ◽

Elastic Anisotropy ◽

Elastic Stability ◽

Lattice Parameters ◽

Structure Stability ◽

First Principles Calculations ◽

Stability Criteria ◽

Modulus Ratio ◽

Isotropic Pressure

The lattice parameters and elastic constants of the tetragonal LiFeAs and NaFeAs under different pressures have been investigated by using the first-principles calculations. It is found that their lattice parameters at 0 GPa are in agreement with the available experimental data. By the elastic stability criteria under isotropic pressure, it is found that LiFeAs and NaFeAs with the tetragonal structure are not mechanically stable above 16 GPa and 18 GPa, respectively. Besides, Pugh’s modulus ratio, Poisson’s ratio, Vickers hardness, and elastic anisotropy factors of LiFeAs in the pressure range of 0–16 GPa and NaFeAs in the pressure range of 0–18 GPa are systematically investigated. It is shown that their ductilities increase with increasing pressure, and the ductility of NaFeAs is superior to that of LiFeAs under different pressures.

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