Mechanical Properties and Stability of Body-Centered-Tetragonal C8 at High Pressures

2018 ◽  
Vol 73 (10) ◽  
pp. 939-945
Author(s):  
Chenyang Zhao ◽  
Qun Wei ◽  
Haiyan Yan ◽  
Bing Wei
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Pressure Range ◽  
Superhard Material ◽  
High Pressures ◽  
Elastic Anisotropy ◽  
Acoustic Velocity ◽  
Large Strains ◽  
First Principles Calculations ◽  
The Ideal

AbstractThe structural, mechanical, electronic properties and stability of body-centered-tetragonal C8 (Bct-C8) were determined by using the first-principles calculations. Bct-C8 is identified to be mechanically and dynamically stable at a pressure range from 0 to 100 GPa. The elastic anisotropy, average acoustic velocity and Debye temperature of Bct-C8 at ambient and high pressures were studied. The ideal stresses at large strains of Bct-C8 were examined; the results showed that it would cleave under the tensile strength of 72 GPa or under the shear strength of 70 GPa, indicating that Bct-C8 is a potential superhard material.

Pressure effects on mechanical and electronic properties of metallic C14 by first-principles calculation

2019 ◽  
Vol 33 (18) ◽  
pp. 1950193
Author(s):  
Yingjiao Zhou ◽  
Qun Wei ◽  
Bing Wei ◽  
Ruike Yang ◽  
Ke Cheng ◽  
...  
Keyword(s):  
High Pressure ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Pressure Range ◽  
Phonon Dispersion ◽  
Elastic Anisotropy ◽  
Acoustic Velocity ◽  
Pressure Effects ◽  
First Principles Calculation ◽  
First Principles Calculations

The elastic constants and phonon dispersion of metallic C[Formula: see text] are calculated by first-principles calculations. The results show that the metallic C[Formula: see text] is mechanically and dynamically stable under high pressure. The variations of G/B ratio, Poisson’s ratio, elastic anisotropy, acoustic velocity and Debye temperature at the pressure range from 0 GPa to 100 GPa are analyzed. The results reveal that by adjusting the pressures the elastic anisotropy and thermodynamic properties could be improved for better applicability.

scholarly journals Mechanical properties and band structure of CdSe and CdTe nanostructures at high pressure - a first-principles study

2019 ◽  
Vol 13 (2) ◽  
pp. 124-131 ◽  
Author(s):  
Natarajan Kishore ◽  
Veerappan Nagarajan ◽  
Ramanathan Chandiramouli
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Shear Modulus ◽  
Band Structure ◽  
First Principles ◽  
Pressure Range ◽  
Uniaxial Pressure ◽  
First Principles Calculations ◽  
Zinc Blende ◽  
Cauchy Pressure

First-principles calculations for CdSe and CdTe nanostructures were carried out to study their mechanical properties and band structure under the uniaxial pressure range of 0 to 50GPa. It was presumed that the CdSe and CdTe nanostructures exist in the zinc-blende phase under high pressure. The mechanical properties, such as elastic constants, bulk modulus, shear modulus and Young?s modulus, were explored. Furthermore, Cauchy pressure, Poisson?s ratio and Pugh?s criterion were studied under high pressure for both CdSe and CdTe nanostructures, and the results show that they exhibit ductile property. The band structure studies of CdSe and CdTe were also investigated. The findings show that the mechanical properties and the band structures of CdSe and CdTe can be tailored with high pressure.

scholarly journals Ultimate Mechanical Properties of Forsterite

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 787 ◽  
Author(s):  
Karine Gouriet ◽  
Philippe Carrez ◽  
Patrick Cordier
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Shear Plane ◽  
Shear Loading ◽  
High Symmetry ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Homogeneous Strain ◽  
The Ideal

The ultimate mechanical properties, as characterized here by the ideal strengths of Mg2SiO4 forsterite, have been calculated using first-principles calculations and generalized gradient approximation under tensile and shear loading. The ideal tensile strengths (ITS) and ideal shear strengths (ISS) are computed by applying homogeneous strain increments along high-symmetry directions ([100], [010], and [001]) and low index shear plane ((100), (010), and (001)) of the orthorhombic lattice. We show that the ultimate mechanical properties of forsterite are highly anisotropic, with ITS ranging from 12.1 GPa along [010] to 29.3 GPa along [100], and ISS ranging from 5.6 GPa for simple shear deformation along (100) to 11.5 GPa for shear along (010).

scholarly journals The Mechanical Properties and Elastic Anisotropy of η’-Cu6Sn5 and Cu3Sn Intermetallic Compounds

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1562
Author(s):  
Chao Ding ◽  
Jian Wang ◽  
Tianhan Liu ◽  
Hongbo Qin ◽  
Daoguo Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
First Principles ◽  
Elastic Anisotropy ◽  
First Principles Calculations ◽  
Anisotropic Behavior ◽  
Ductile Materials ◽  
The Relationship

Full intermetallic compound (IMC) solder joints present fascinating advantages in high-temperature applications. In this study, the mechanical properties and elastic anisotropy of η’-Cu6Sn5 and Cu3Sn intermetallic compounds were investigated using first-principles calculations. The values of single-crystal elastic constants, the elastic (E), shear (G), and bulk (B) moduli, and Poisson’s ratio (ν) were identified. In addition, the two values of G/B and ν indicated that the two IMCs were ductile materials. The elastic anisotropy of η’-Cu6Sn5 was found to be higher than Cu3Sn by calculating the universal anisotropic index. Furthermore, an interesting discovery was that the above two types of monocrystalline IMC exhibited mechanical anisotropic behavior. Specifically, the anisotropic degree of E and B complied with the following relationship: η’-Cu6Sn5 > Cu3Sn; however, the relationship was Cu3Sn > η’-Cu6Sn5 for the G. It is noted that the anisotropic degree of E and G was similar for the two IMCs. In addition, the anisotropy of the B was higher than the G and E, respectively, for η’-Cu6Sn5; however, in the case of Cu3Sn, the anisotropic degree of B, G, and E was similar.

First-Principles Investigations on the Elastic Properties of Platinum Group Metals (Pt, Pd, and Ru)

2019 ◽  
Vol 944 ◽  
pp. 761-769 ◽  
Author(s):  
Ying Jie Sun ◽  
Kai Xiong ◽  
Shun Meng Zhang ◽  
Yong Mao
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Platinum Group Metals ◽  
First Principles Calculations ◽  
New Materials ◽  
Functional Theory ◽  
Platinum Group ◽  
Microscopic Deformation

The structural, mechanical, and thermodynamic properties of platinum group metals (Pt, Pd, and Ru) were systematically investigated by first-principles calculations based on density functional theory. Comparative studies show that Ru has the best comprehensive mechanical properties. Based on the Pugh’s rule and Poisson’s ratio, it is judged that Pt and Pd are ductility materials, and Ru exhibits obvious brittleness. Furthermore, the elastic anisotropy is also discussed by plotting both the 3D contours and the 2D planar projections of Young's modulus and shear modulus. The predicted elastic anisotropy factors indicate that the degree of elastic anisotropy of Pd is significant, while Ru has the smallest elastic anisotropy. By using the Clarke’s model, the minimum thermal conductivities of these metals have also been analyzed, and the results indicate that the low minimum thermal conductivity is proportional to the Debye temperature ΘD. The above results can provide a valuable reference for revealing the microscopic deformation mechanism and designing new materials.

Structural, elastic and electronic properties of new superhard orthorhombic C28

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.

Pressure and Strain Effects on the Structural, Electronic, and Optical Properties of K4 Phosphorus

2018 ◽  
Vol 73 (7) ◽  
pp. 661-668 ◽  
Author(s):  
Chenyang Zhao ◽  
Qun Wei ◽  
Meiguang Zhang ◽  
Haiyan Yan ◽  
Xinchao Yang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Optical Properties ◽  
Hydrostatic Pressure ◽  
Tensile Strain ◽  
Elastic Anisotropy ◽  
Acoustic Velocity ◽  
Large Strains ◽  
Electronic And Optical Properties ◽  
Made In ◽  
The Ideal

AbstractAn investigation of the mechanical, electronic, and optical properties of the recently reported material K4 phosphorus was made in this work. K4 phosphorus has been proved to be mechanically and dynamically stable up to 7 GPa under hydrostatic pressure. We compared the elastic anisotropy, average acoustic velocity, and Debye temperature of K4 phosphorus at 0 and 7 GPa. The ideal tensile properties at large strains of K4 phosphorus were also examined, with the results showing that it would cleave under the tensile strength of 8.5 GPa with the strain of 0.3. In addition, the effect of tensile strain and pressure on optical properties and band gap were studied.

scholarly journals Ternary superconducting cophosphorus hydrides stabilized via lithium

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Ziji Shao ◽  
Defang Duan ◽  
Yanbin Ma ◽  
Hongyu Yu ◽  
Hao Song ◽  
...  
Keyword(s):  
High Pressure ◽  
First Principles ◽  
Structure Prediction ◽  
Pressure Range ◽  
High Temperature Superconductor ◽  
High Pressures ◽  
Experimental Studies ◽  
First Principles Calculations ◽  
Ternary Compounds ◽  
Stable Structures

Abstract Inspired by the diverse properties of sulfur hydrides and phosphorus hydrides, we combine first-principles calculations with structure prediction to search for stable structures of Li−P−H ternary compounds at high pressures with the aim of finding novel superconductors. It is found that phosphorus hydrides can be stabilized under pressure via additional doped lithium. Four stable stoichiometries LiPH3, LiPH4, LiPH6, and LiPH7 are uncovered in the pressure range of 100–300 GPa. Notably, we find an atomic LiPH6 with $$Pm\overline 3$$ P m 3 ¯ symmetry which is predicted to be a potential high-temperature superconductor with a Tc value of 150–167 K at 200 GPa and the Tc decreases upon compression. All the predicted stable ternary hydrides contain the P–H covalent frameworks with ionic lithium staying beside, but not for $$Pm\overline 3$$ P m 3 ¯ -LiPH6. We proposed a possible synthesis route for ternary lithium phosphorus hydrides: LiP + H2 → LiPHn, which could provide helpful and clear guidance to further experimental studies. Our work may provide some advice on further investigations on ternary superconductive hydrides at high pressure.

Comparative study of 9R and 12R hexagonal diamond by first-principles calculations

2018 ◽  
Vol 32 (20) ◽  
pp. 1850211
Author(s):  
Qian Wang ◽  
Quan Zhang
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Comparative Study ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Elastic Anisotropy ◽  
First Principles Calculations ◽  
Ideal Strength ◽  
Superhard Materials

The structural and mechanical properties of 9R diamond and 12R diamond have been investigated by using the first-principles calculations. The elastic constants, bulk modulus and Young’s modulus at various pressures have been investigated. The elastic anisotropy under pressure from 0 to 100 GPa has been studied. From our calculations, we found that 9R diamond and 12R diamond have similar high elastic constants and elastic modulus as lonsdaleite and diamond. The detailed ideal strength calculations show that 9R diamond and 12R diamond are intrinsic superhard materials.

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