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.

Ab Initio Study of the Structural and Mechanical Properties of Hf-Si-N

2010 ◽  
Vol 139-141 ◽  
pp. 22-25 ◽  
Author(s):  
Xin Tan ◽  
Yu Qing Li ◽  
Xue Jie Liu ◽  
De Gong Liu
Keyword(s):  
Mechanical Properties ◽  
First Principles ◽  
Cohesive Energy ◽  
Density Functional ◽  
Substitutional Solid Solution ◽  
Lattice Parameter ◽  
Solution Phase ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory

The structural and elastic properties of HfN and Hf-Si-N have been studied, using first principles calculations based on the density functional theory. These calculations provide the lattice parameter, cohesive energy and elastic constants of fcc (NaCl)-HfN, the N-deficient Hf-Si-N and the Hf-deficient Hf-Si-N solution phase. In order to study the relative stability, binding energy of all configurations has been calculated. The results showed that it was difficult to add a Si atom into the center of the HfN cell because the cohesive energy decreased. However, if an Hf atom or an N atom was missing in the HfN, a silicon atom was possible to occupy the vacant site and form the Hf-Si-N substitutional solid solution. Moreover, the bulk modulus, shear modulus and elastic modulus increased accordingly, the mechanical properties were improved.

scholarly journals Magneto-electric multiferroics: designing new materials from first-principles calculations

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Julien Varignon ◽  
Nicholas C. Bristowe ◽  
Eric Bousquet ◽  
Philippe Ghosez
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
First Principles Calculations ◽  
New Materials ◽  
Multiferroic Materials ◽  
Functional Theory ◽  
Multifunctional Material ◽  
In The Beginning ◽  
Theoretical Developments

Abstract In parallel with the revival of interest for magneto-electric multiferroic materials in the beginning of the century, first-principles simulations have grown incredibly in efficiency during the last two decades. Density functional theory calculations, in particular, have so become a must-have tool for physicists and chemists in the multiferroic community. While these calculations were originally used to support and explain experimental behaviour, their interest has progressively moved to the design of novel magneto-electric multiferroic materials. In this article, we mainly focus on oxide perovskites, an important class of multifunctional material, and review some significant advances to which contributed first-principles calculations. We also briefly introduce the various theoretical developments that were at the core of all these advances.

First-principles calculations of stability, electronic and elastic properties of the precipitates present in 7055 aluminum alloy

2018 ◽  
Vol 32 (09) ◽  
pp. 1850104 ◽  
Author(s):  
Cheng Huang ◽  
Hongbang Shao ◽  
Yunlong Ma ◽  
Yuanchun Huang ◽  
Zhengbing Xiao
Keyword(s):  
Aluminum Alloy ◽  
Elastic Properties ◽  
Structural Stability ◽  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Structural Parameters ◽  
First Principles Calculations ◽  
Functional Theory ◽  
7055 Aluminum Alloy

The structural stability, electronic structures and elastic properties of the strengthening precipitates, namely Al3Zr, MgZn2, Al2CuMg and Al2Cu, present in 7055 aluminum alloy were investigated by the first-principles calculations based on density functional theory (DFT). The optimized structural parameters are in good agreement with literature values available. It is found that Al3Zr has the strongest alloying ability and structural stability, while for MgZn2, its structural stability is the worst. The calculated electronic results indicate that covalent bonding is the dominant cohesion of Al3Zr, whereas the fractional ionic interactions coexisting with metallic bonding are found in MgZn2, Al2CuMg and Al2Cu. The elastic constants C[Formula: see text] of these precipitates were calculated, and the bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and universal elastic anisotropy were derived. It is suggested that MgZn2 is ductile, whereas Al3Zr, Al2CuMg and Al2Cu are brittle, and the elastic anisotropies of them increase in the following sequence: Al3Zr[Formula: see text]MgZn2[Formula: see text]Al2CuMg[Formula: see text]Al2Cu. The formation of MgZn2 and Al3Zr should be promoted by increasing the compositions of Zn and Zr to improve the alloy’s performance further.

Structural and Elastic Properties of Antimony Triiodide from First-Principles Calculations

2013 ◽  
Vol 750-752 ◽  
pp. 1782-1785
Author(s):  
Xiao Xiao Sun ◽  
Chun Lei Wu ◽  
Wei Wei Chen ◽  
Hai Sheng Liu
Keyword(s):  
Experimental Data ◽  
Elastic Properties ◽  
First Principles ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Structural Parameters ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Space Groups ◽  
Calculated Equilibrium

First principles calculations are performed to investigate the structural and elastic properties of SbI3 based on density functional theory for two space groups: trigonal R-3 and monoclinic P21/c. The calculated equilibrium structural parameters agree well with the experimental data. The enthalpy calculations confirm that the trigonal R-3 structure of SbI3 is the most stable structure at zero pressure. For R-3 structure, the obtained bulk, shear, and Youngs modulus are 28.1, 15.2 and 38.6 GPa, respectively. The calculated Debye temperature is 197 K. SbI3 presents large elastic anisotropy, stronger compressibility and better ductility at 0 GPa.

scholarly journals A First-Principles Study of the Cu-Containing β″ Precipitates in Al-Mg-Si-Cu Alloy

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7879
Author(s):  
Shaozhi He ◽  
Jiong Wang ◽  
Donglan Zhang ◽  
Qing Wu ◽  
Yi Kong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Electron Interaction ◽  
Structure Stability ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Cu Alloy ◽  
Work First

The nanostructured β″ precipitates are critical for the strength of Al-Mg-Si-(Cu) aluminum alloys. However, there are still controversial reports about the composition of Cu-containing β″ phases. In this work, first-principles calculations based on density functional theory were used to investigate the composition, mechanical properties, and electronic structure of Cu-containing β″ phases. The results predict that the Cu-containing β″ precipitates with a stoichiometry of Mg4+xAl2−xCuSi4 (x = 0, 1) are energetically favorable. As the concentration of Cu atoms increases, Cu-containing β″ phases with different compositions will appear, such as Mg4AlCu2Si4 and Mg4Cu3Si4. The replacement order of Cu atoms in β″ phases can be summarized as one Si3/Al site → two Si3/Al sites → two Si3/Al sites and one Mg1 site. The calculated elastic constants of the considered β″ phases suggest that they are all mechanically stable, and all β″ phases are ductile. When Cu atoms replace Al atoms at Si3/Al sites in β″ phases, the values of bulk modulus (B), shear modulus (G), and Young’s modulus (E) all increase. The calculation of the phonon spectrum shows that Mg4+xAl2−xCuSi4 (x = 0, 1) are also dynamically stable. The electronic structure analysis shows that the bond between the Si atom and the Cu atom has a covalent like property. The incorporation of the Cu atom enhances the electron interaction between the Mg2 and the Si3 atom so that the Mg2 atom also joins the Si network, which may be one of the reasons why Cu atoms increase the structure stability of the β″ phases.

Thermodynamic Stability of Hexagonal and Rhombohedral Bn at Cvd Conditions from Van der Waals Corrected First Principles Calculations

2019 ◽  
Author(s):  
Henrik Pedersen ◽  
Björn Alling ◽  
Hans Högberg ◽  
Annop Ektarawong
Keyword(s):  
Thin Films ◽  
Thermodynamic Stability ◽  
First Principles ◽  
Thermal Equilibrium ◽  
Density Functional ◽  
Van Der Waals ◽  
Chemical Vapor ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Stability

Thin films of boron nitride (BN), particularly the sp<sup>2</sup>-hybridized polytypes hexagonal BN (h-BN) and rhombohedral BN (r-BN) are interesting for several electronic applications given band gaps in the UV. They are typically deposited close to thermal equilibrium by chemical vapor deposition (CVD) at temperatures and pressures in the regions 1400-1800 K and 1000-10000 Pa, respectively. In this letter, we use van der Waals corrected density functional theory and thermodynamic stability calculations to determine the stability of r-BN and compare it to that of h-BN as well as to cubic BN and wurtzitic BN. We find that r-BN is the stable sp<sup>2</sup>-hybridized phase at CVD conditions, while h-BN is metastable. Thus, our calculations suggest that thin films of h-BN must be deposited far from thermal equilibrium.

scholarly journals Hydrogenation and oxidation enhances the thermoelectric performance of Si2BN monolayer

2021 ◽  
Author(s):  
H. R. Mahida ◽  
Deobrat Singh ◽  
Yogesh Sonvane ◽  
Sanjeev K. Gupta ◽  
P. B. Thakor ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Charge Transport ◽  
Transport Properties ◽  
First Principles ◽  
Density Functional ◽  
Thermoelectric Performance ◽  
First Principles Calculations ◽  
Functional Theory

In the present study, we have investigated the structural, electronic, and charge transport properties of pristine, hydrogenated, and oxidized Si2BN monolayers via first-principles calculations based on density functional theory (DFT).

Probing the electronic structures of Con (n = 1–5) clusters on γ-Al2O3 surfaces using first-principles calculations

2017 ◽  
Vol 19 (5) ◽  
pp. 3679-3687 ◽  
Author(s):  
Tao Yang ◽  
Masahiro Ehara
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
First Principles Calculations ◽  
Functional Theory

Using density functional theory calculations, we discussed the geometric and electronic structures and nucleation of small Co clusters on γ-Al2O3(100) and γ-Al2O3(110) surfaces.

Electronic structure of cubic BaTbO3 from first-principles pseudopotential calculations

2006 ◽  
Vol 84 (2) ◽  
pp. 115-120 ◽  
Author(s):  
G Y Gao ◽  
K L Yao ◽  
Z L Liu
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Exchange Correlation ◽  
Pseudopotential Calculations ◽  
Correlation Potential ◽  
Density Contour

First-principles calculations of the electronic structure are performed for cubic BaTbO3 using the plane-wave pseudopotential method within the framework of density functional theory and using the generalized gradient approximation for the exchange-correlation potential. Our calculations show that cubic BaTbO3 is metallic, and that this metallic character is mainly governed by the Tb 4f electrons and the hybridization between the Tb 5d and O 2p states. From the analysis of the density of states, band structure, and charge density contour, we find that the chemical bonding between Tb and O is covalent while that between Ba and TbO3 is ionic. PACS Nos.: 71.15.Mb, 71.20.-b

Computational investigation of NH3 adsorption and dehydrogenation on a W-modified Fe(111) surface

2015 ◽  
Vol 17 (45) ◽  
pp. 30598-30605 ◽  
Author(s):  
Ming-Kai Hsiao ◽  
Chia-Hao Su ◽  
Ching-Yang Liu ◽  
Hui-Lung Chen
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculations ◽  
Computational Investigation ◽  
Functional Theory ◽  
Nh3 Adsorption ◽  
Tungsten Metal

We employed monolayer tungsten metal to modify the Fe(111) surface, denoted as W@Fe(111), and calculated the adsorption and dehydrogenation behaviors of NH3 on W@Fe(111) surface via first-principles calculations based on density functional theory (DFT).

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