Mechanical degradation of graphene by epoxidation: insights from first-principles calculations

2015 ◽  
Vol 17 (29) ◽  
pp. 19484-19490 ◽  
Author(s):  
Qing Peng ◽  
Liang Han ◽  
Jie Lian ◽  
Xiaodong Wen ◽  
Sheng Liu ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
First Principles ◽  
Young's Modulus ◽  
Mechanical Degradation ◽  
First Principles Calculations

The in-plane Young's modulus decreases with the degree of epoxidation.

Tension-induced mechanical properties of stanene

2016 ◽  
Vol 30 (12) ◽  
pp. 1650146 ◽  
Author(s):  
Lele Tao ◽  
Chuanghua Yang ◽  
Liyuan Wu ◽  
Lihong Han ◽  
Yuxin Song ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Young's Modulus ◽  
Poisson Ratio ◽  
Group Iv ◽  
First Principles Calculations ◽  
Stress Strain Relation ◽  
Group Iv Elements ◽  
Internal Atom

In this paper, elastic properties of stanene under equiaxial or uniaxial tensions along armchair and zigzag directions are investigated by first-principles calculations. The stress–strain relation is calculated and the relaxation of the internal atom positions is analyzed. The high-order elastic constants are calculated by fitting the polynomial expressions. The Young’s modulus and Poisson ratio of the stanene is calculated to be 24.14 N/m and 0.39 N/m, respectively. The stanene exhibits lower Young’s modulus than those of the proceeding group IV elements, which is attributed to the smaller [Formula: see text]–[Formula: see text] bond energy in stanene than those of silicene and germanene. Calculated values of ultimate stresses and strains, second-order elastic constants (SOCEs) and the in-plane Young’s modulus are all positive. It proves that stanene is mechanically stable.

First-principles calculations for mechanical and electronic features of strained GaP nanowires

2017 ◽  
Vol 28 (03) ◽  
pp. 1750039 ◽  
Author(s):  
Rezek Mohammad ◽  
Şenay Katırcıoğlu
Keyword(s):  
Band Gap ◽  
Young’S Modulus ◽  
First Principles ◽  
Energy Band ◽  
Density Functional ◽  
Young's Modulus ◽  
First Principles Calculations ◽  
Effective Electron ◽  
Young’S Moduli ◽  
Effective Carrier

The mechanical and electronic properties of GaP nanowires are investigated by computing the Young’s modulus, Poisson’s ratio, energy band gap and effective carrier masses using first-principles calculations based on density functional theory. The wurtzite structural nanowires with diameters upper limited to [Formula: see text][Formula: see text]Å are strained by uniaxial strains in the range of [Formula: see text]–[Formula: see text]. The Young’s moduli of nanowires are found to be decreased with increase of the size in the direction of the Young’s modulus of the bulk GaP. The Poisson’s effect is determined to be stronger in GaP nanowires than in the bulk. The energy band gaps of the unstrained and strained nanowires are obtained to be enlarged with decrease of the size due to the quantum size effect. The confinement effect is found larger in the compressed nanowires than in the stretched ones. All the unstrained nanowires except the largest one are indirect band gap materials. Indirect to direct band gap transition is determined to be size and strain dependent. The effective carrier masses in all unstrained nanowires are found small compared to the ones in the bulk GaP. The effective electron and hole masses are obtained to be modulated in nanowires of this work by the compressive and both compressive/tensile strains, respectively.

Pressure Effect on the Structural, Elastic and Electronic Behaviors of Li3Bi: Ab Initio Study

2013 ◽  
Vol 641-642 ◽  
pp. 479-482 ◽  
Author(s):  
Xiao Xiao Sun
Keyword(s):  
Shear Modulus ◽  
Ab Initio ◽  
Electronic Properties ◽  
Young’S Modulus ◽  
First Principles ◽  
Pressure Effect ◽  
Young's Modulus ◽  
Lattice Parameters ◽  
First Principles Calculations ◽  
G Ratio

First principles calculations have been performed to investigate the elastic and electronic behaviors of Li3Bi as a function of pressure from 0 GPa to 100 GPa with a step 10 GPa. Our calculations indicate that the lattice parameters and volume of cubic Li3Bi decrease with the increasing pressure. Cubic Fm-3m structure of Li3Bi is more mechanically stable at pressures of up to 100 GPa. The calculated results of the bulk, shear, Young’s modulus, B/G ratio of Li3Bi as a function of pressure show that Li3Bi has higher bulk, shear modulus and better ductility at 0 GPa than 50 GPa. The analysis of electronic properties reveals that the covalent Bi-Li bonding plays an important role in hardness and incompressibility of Li3Bi.

scholarly journals First principles computation of composition dependent elastic constants of omega in titanium alloys: implications on mechanical behavior

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Salloom ◽  
S. A. Mantri ◽  
R. Banerjee ◽  
S. G. Srinivasan
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
First Principles ◽  
Young's Modulus ◽  
Group Vi ◽  
Group V ◽  
Β Phase ◽  
Ti Alloys ◽  
Ω Phase ◽  
Stabilizer Concentration

AbstractFor decades the poor mechanical properties of Ti alloys were attributed to the intrinsic brittleness of the hexagonal ω-phase that has fewer than 5-independent slip systems. We contradict this conventional wisdom by coupling first-principles and cluster expansion calculations with experiments. We show that the elastic properties of the ω-phase can be systematically varied as a function of its composition to enhance both the ductility and strength of the Ti-alloy. Studies with five prototypical β-stabilizer solutes (Nb, Ta, V, Mo, and W) show that increasing β-stabilizer concentration destabilizes the ω-phase, in agreement with experiments. The Young’s modulus of ω-phase also decreased at larger concentration of β-stabilizers. Within the region of ω-phase stability, addition of Nb, Ta, and V (Group-V elements) decreased Young’s modulus more steeply compared to Mo and W (Group-VI elements) additions. The higher values of Young’s modulus of Ti–W and Ti–Mo binaries is related to the stronger stabilization of ω-phase due to the higher number of valence electrons. Density of states (DOS) calculations also revealed a stronger covalent bonding in the ω-phase compared to a metallic bonding in β-phase, and indicate that alloying is a promising route to enhance the ω-phase’s ductility. Overall, the mechanical properties of ω-phase predicted by our calculations agree well with the available experiments. Importantly, our study reveals that ω precipitates are not intrinsically embrittling and detrimental, and that we can create Ti-alloys with both good ductility and strength by tailoring ω precipitates' composition instead of completely eliminating them.

Effect of Ce Substitution on Mechanical and Thermal Properties of Tetragonal YSZ: First-Principles Calculations

2015 ◽  
Vol 1120-1121 ◽  
pp. 73-84
Author(s):  
Lei Jin ◽  
Pei Zhong Li ◽  
Guo Dong Zhou ◽  
Wei Gao ◽  
Jiang Ning Ma ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Sound Velocity ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Density Functional ◽  
Young's Modulus ◽  
Mechanical And Thermal Properties ◽  
Ce Substitution

The effect of impurity Ce on the mechanical and thermal properties of tetragonal ZrO2 stabilized by rare earth element Y (YSZ) have been studied using first principles density functional theory within generalized gradient approximation (GGA) for the exchange correlation potential. The predicted elastic constants indicate that YSZ and Ce doped YSZ (CeYSZ) are mechanically stable structures. And then the numerical estimates of bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, sound velocity and minimum thermal conductivity were performed using the calculated elastic constants and analyzed for the first time. The values of sound velocity from different orientations are also reported. The agreement between the results of the available experiments and our calculations was satisfactory. Our calculated results indicate that Young’s modulus, hardness, mean sound velocity and minimum thermal conductivity of YSZ can be decreased by Ce substitution. The reasons are from the “softened” Ce-O bond strength using bond population and relative volume change under external hydrostatic pressure. Chemical bonding nature was also analyzed from the density of states and electron density difference.

A first-principles study of the properties of two novel Si3P4 phases

2018 ◽  
Vol 32 (22) ◽  
pp. 1850244 ◽  
Author(s):  
Ruike Yang ◽  
Bao Chai ◽  
Qun Wei ◽  
Dongyun Zhang
Keyword(s):  
Optical Properties ◽  
Young’S Modulus ◽  
Absorption Spectra ◽  
First Principles ◽  
Phonon Dispersion ◽  
Young's Modulus ◽  
Dielectric Constants ◽  
Loss Functions ◽  
Deformation Ability ◽  
Two Phases

The structural, elastic, electronic and optical properties of two novel phases Si3P4 with tetragonal and orthorhombic structures are studied by first-principles calculations according to density function theory (DFT). For novel structures t-Si3P4 and o-Si3P4, the elastic constants results show that they are mechanically stable. The phonon dispersion spectra confirm that they are dynamically stable. The forming enthalpies prove their thermodynamic stability. The mechanical properties, such as the bulk modulus B, shear modulus G, Pugh ratio k, Young’s modulus E and Poisson’s ratios [Formula: see text] are calculated. The results show that t-Si3P4 has better anti-deformation ability than o-Si3P4, and t-Si3P4 is harder than o-Si3P4. The Poisson’s ratio values of t-Si3P4 and o-Si3P4 are 0.16 and 0.35, and the Pugh ratio values, k, are 0.88 and 0.33. For t-Si3P4, the Pugh ratio k [Formula: see text] 0.57 indicates that it behaves in a brittle manner. For o-Si3P4, it owns the better plasticity. The directional dependence of the Young’s modulus indicates that o-Si3P4 is more anisotropic than t-Si3P4. The calculated band structures show that the two novel phases are semiconductors, and the narrow indirect bandgaps are 1.847 and 0.158 eV by using PBE0. The densities of states (DOS) indicate that the P ‘p’ and Si ‘p’ play major roles in two phases total DOS. The results of the optical properties, such as the dielectric functions, absorption spectra, loss functions, refractive index, and so on are given. The static dielectric constants are 5.493 and 12.206, the starting positions of the absorption spectra are approximately at 1.815 and 0.140 eV, and the peaks of loss functions are at 15.503 and 11.763 eV, for t-Si3P4 and o-Si3P4, respectively.

scholarly journals First-principles investigations on the anisotropic elasticity and thermodynamic properties of U3Si2–Al

RSC Advances ◽  
2020 ◽  
Vol 10 (58) ◽  
pp. 35049-35056
Author(s):  
Xinyu Chen ◽  
Yanqing Qin ◽  
Diwei Shi ◽  
Yaolin Guo ◽  
Moran Bu ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Young’S Modulus ◽  
First Principles ◽  
Elastic Anisotropy ◽  
Young's Modulus ◽  
Three Dimensional ◽  
Anisotropic Elasticity

Three-dimensional Young's modulus diagrams of different structures are used to judge the degree of elastic anisotropy.

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