First-Principles Calculations of Elastic Properties of HoBi and ErBi

2013 ◽  
Vol 664 ◽  
pp. 672-676
Author(s):  
De Ming Han ◽  
Gang Zhang ◽  
Li Hui Zhao
Keyword(s):  
Shear Modulus ◽  
Physical Properties ◽  
Bulk Modulus ◽  
Elastic Properties ◽  
Lattice Constant ◽  
Elastic Constants ◽  
First Principles ◽  
Energy Band ◽  
First Principles Calculations ◽  
Future Work

We present first-principles investigations on the elastic properties of XBi (X=Ho, Er) compounds. Basic physical properties, such as lattice constant, elastic constants (Cij), isotropic shear modulus (G), bulk modulus (B), Young’s modulus (Y), Poisson’s ratio (υ), and Anisotropy factor (A) are calculated. The calculated energy band structures show that the two compounds possess semi-metallic character. We hope that these results would be useful for future work on two compounds.

First-Principles Study of the Mechanical Properties of ScAl Microalloyed by 4d-Transition Metals

2014 ◽  
Vol 852 ◽  
pp. 198-202
Author(s):  
Shuo Huang ◽  
Chuan Hui Zhang ◽  
Rui Zi Li ◽  
Jing Sun ◽  
Jiang Shen
Keyword(s):  
Mechanical Properties ◽  
Transition Metals ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
First Principles Calculations ◽  
Cauchy Pressure ◽  
Theoretical Results ◽  
Elastic Coefficients

The structural and elastic properties of B2 ScAl doped with Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag and Cd elements are studied by using first-principles calculations. The calculated elastic coefficients of pure ScAl are consistent with other theoretical results. The results of elastic constants indicate that all the ScAl-based alloys discussed are mechanically stable. The bulk modulusB, shear modulusG, Youngs modulusY, Pugh ratioB/Gand Cauchy pressure (C12-C44) are investigated. It is found that the addition of Ru that prefers Al site in ScAl can increase the stiffness of ScAl and improve its ductility.

scholarly journals Mechanical and Thermal Conductivity Properties of Enhanced Phases in Mg-Zn-Zr System from First Principles

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2010
Author(s):  
Shuo Wang ◽  
Yuhong Zhao ◽  
Huijun Guo ◽  
Feifei Lan ◽  
Hua Hou
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Intermetallic Compounds ◽  
Elastic Constants ◽  
First Principles ◽  
Strengthening Phases ◽  
Zr Alloy ◽  
Zr Alloys

In this paper, the mechanical properties and minimum thermal conductivity of ZnZr, Zn2Zr, Zn2Zr3, and MgZn2 are calculated from first principles. The results show that the considered Zn-Zr intermetallic compounds are effective strengthening phases compared to MgZn2 based on the calculated elastic constants and polycrystalline bulk modulus B, shear modulus G, and Young’s modulus E. Meanwhile, the strong Zn-Zr ionic bondings in ZnZr, Zn2Zr, and Zn2Zr3 alloys lead to the characteristics of a higher modulus but lower ductility than the MgZn2 alloy. The minimum thermal conductivity of ZnZr, Zn2Zr, Zn2Zr3, and MgZn2 is 0.48, 0.67, 0.68, and 0.49 W m−1 K−1, respectively, indicating that the thermal conductivity of the Mg-Zn-Zr alloy could be improved as the precipitation of Zn atoms from the α-Mg matrix to form the considered Zn-Zr binary alloys. Based on the analysis of the directional dependence of the minimum thermal conductivity, the minimum thermal conductivity in the direction of [110] can be identified as a crucial short limit for the considered Zn-Zr intermetallic compounds in Mg-Zn-Zr alloys.

Temperature Dependences of the Elastic Constants of Precipitation-Hardened Aluminum Alloys 2014 and 2219

1977 ◽  
Vol 99 (2) ◽  
pp. 181-184 ◽  
Author(s):  
D. T. Read ◽  
H. M. Ledbetter
Keyword(s):  
Aluminum Alloys ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Temperature Dependence ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Ultrasonic Pulse ◽  
Young’S Moduli ◽  
Temperature Dependences ◽  
Sound Velocities

Elastic properties of precipitation-hardened aluminum alloys 2014 and 2219 were studied between 4 and 300 K using ultrasonic pulse techniques. Both the longitudinal and transverse sound velocities were measured. Also reported are the Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio. For both alloys, the Young’s moduli are about ten percent higher than for unalloyed aluminum, and they increase about ten percent on cooling from 300 to 4 K. All the elastic constants show normal temperature dependence.

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.

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.

scholarly journals The Third-Order Elastic Constants and Mechanical Properties of 30° Partial Dislocation in Germanium: A Study from the First-Principles Calculations and the Improved Peierls−Nabarro Model

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 4
Author(s):  
Huili Zhang ◽  
Defang Lu ◽  
Yu Sun ◽  
Yunchang Fu ◽  
Lumei Tong
Keyword(s):  
Lattice Constant ◽  
Elastic Constants ◽  
First Principles ◽  
Partial Dislocation ◽  
Stacking Fault ◽  
Peierls Stress ◽  
First Principles Calculations ◽  
Third Order ◽  
The Third ◽  
Core Width

The elastic constants, core width and Peierls stress of partial dislocation in germanium has been investigated based on the first-principles calculations and the improved Peierls−Nabarro model. Our results suggest that the predictions of lattice constant and elastic constants given by LDA are in better agreement with experiment results. While the lattice constant is overestimated at about 2.4% and most elastic constants are underestimated at about 20% by the GGA method. Furthermore, when the applied deformation is larger than 2%, the nonlinear elastic effects should be considered. And with the Lagrangian strains up to 8%, taking into account the third-order terms in the energy expansion is sufficient. Except the original γ—surface generally used before (given by the first-principles calculations directly), the effective γ—surface proposed by Kamimura et al. derived from the original one is also used to study the Peierls stress. The research results show that when the intrinsic−stacking−fault energy (ISFE) is very low relative to the unstable−stacking−fault energy (USFE), the difference between the original γ—surface and the effective γ—surface is inapparent and there is nearly no difference between the results of Peierls stresses calculated from these two kinds of γ—surfaces. As a result, the original γ—surface can be directly used to study the core width and Peierls stress when the ratio of ISFE to the USFE is small. Since the negligence of the discrete effect and the contribution of strain energy to the dislocation energy, the Peierls stress given by the classical Peierls−Nabarro model is about one order of magnitude larger than that given by the improved Peierls−Nabarro model. The result of Peierls stress estimated by the improved Peierls−Nabarro model agrees well with the 2~3 GPa reported in the book of Solid State Physics edited by F. Seitz and D. Turnbull.

First Principles Calculations of Phase Stabilities of YNi2 and YMgNi4

2010 ◽  
Vol 152-153 ◽  
pp. 1632-1635 ◽  
Author(s):  
Jian Gang Niu ◽  
Hai En Xiang ◽  
Xiao Ping Dong ◽  
Li Guan ◽  
Fei Xie
Keyword(s):  
Melting Point ◽  
Stress Relaxation ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
First Principles Calculations ◽  
Relative Stabilities ◽  
Ionic Contribution

First-principles calculations were performed to study the relative stabilities of YNi2 and YMgNi4.The calculated results show that YMgNi4 has the higher stability than YNi2, duing to stress relaxation and ionic contribution. The preferential stability of YMgNi4 has been confirmed by calculating elastic constants and melting points.The calculated results show that YMgNi4 has the larger bulk modulus and melting point than YNi2.

Understanding The Nb-Ti-A1 System: First Principles Calculations

1994 ◽  
Vol 364 ◽  
Author(s):  
Michael J. Mehl
Keyword(s):  
High Temperature ◽  
Bulk Modulus ◽  
Total Energy ◽  
Crystal Structures ◽  
Lattice Constant ◽  
Density Of States ◽  
First Principles ◽  
First Principles Calculations ◽  
Electronic Density ◽  
Cubic Phases

AbstractThe discovery of ductile cubic phases in the Nb-Ti-Al system has led to increased study of these high-temperature intermetallics. I have performed first-principles calculations for ordered crystal structures in this system, paying particular attention to the Nb7Ti7Al2 structure. Somewhat surprisingly, the electronic density of states, lattice constant, and bulk modulus are nearly independent of the ordering of these materials, even though the changes in the total energy are significant.

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

2016 ◽  
Vol 71 (6) ◽  
pp. 517-524 ◽  
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.

First-Principles Calculations of Structural and Elastic Properties of Hexagonal Boron Nitride

2009 ◽  
Vol 79-82 ◽  
pp. 1337-1340 ◽  
Author(s):  
Liu Xiao ◽  
Wen Jun He ◽  
Yan Sheng Yin
Keyword(s):  
Boron Nitride ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
First Principles ◽  
Hexagonal Boron Nitride ◽  
Applied Pressure ◽  
Axial Ratio ◽  
First Principles Calculations ◽  
Calculation Results ◽  
Good Agreement

The lattice parameters, five independent elastic constants and the bulk modulus B on the applied pressure of hexagonal boron nitride (h-BN) are calculated by using a first-principles pseudopotential method. The calculation results are in good agreement with the experimental and theoretical values. It is found that the most stable structure of h-BN corresponds to the axial ratio c/a of about 2.652.

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