scholarly journals The effect of vanadium-carbon monolayer on the adsorption of tungsten and carbon atoms on tungsten-carbide (0001) surface

2011 ◽  
Vol 43 (2) ◽  
pp. 153-159
Author(s):  
A. Moitra ◽  
S. Kim ◽  
S.J. Park ◽  
S.G. Kim ◽  
M.F. Horstemeyer
Keyword(s):  
Total Energy ◽  
Tungsten Carbide ◽  
Grain Growth ◽  
Adsorption Energy ◽  
First Principles ◽  
Adsorption Process ◽  
First Principles Calculations ◽  
Fundamental Understanding

We report a first-principles calculations to study the effect of a vanadium-carbon (VC) monolayer on the adsorption process of tungsten (W) and carbon (C) atoms onto tungsten-carbide (WC) (0001) surface. The essential configuration for the study is a supercell of hexagonal WC with a (0001) surface. When adding the VC monolayer, we employed the lowest energy configuration by examining various configurations. The total energy of the system is computed as a function of the W or C adatoms? height from the surface. The adsorption of a W and C adatom on a clean WC (0001) surface is compared with that of a W and C adatom on a WC (0001) surface with VC monolayer. The calculations show that the adsorption energy increased for both W and C adatoms in presence of the VC monolayer. Our results provide a fundamental understanding that can explain the experimentally observed phenomena of inhibited grain growth during sintering of WC or WC-Co powders in presence of VC.

Grain Refining Behavior of Zr, Al2Y and Al4C3 Particles in Magnesium Alloys by the First-Principles Calculations

2015 ◽  
Vol 816 ◽  
pp. 370-374
Author(s):  
Jun Ling Pan ◽  
Qiu Ming Peng ◽  
Jian Xin Guo ◽  
Hui Li
Keyword(s):  
Mechanical Properties ◽  
Structural Optimization ◽  
Magnesium Alloys ◽  
Density Of States ◽  
Adsorption Energy ◽  
First Principles ◽  
Adsorption Process ◽  
Mg Alloys ◽  
Grain Refining ◽  
First Principles Calculations

Grain refining is one of the most important issues in the applications of Mg alloys, which directly determines mechanical properties and deformability. Therefore the understanding of grain refining mechanism during solidification will be benefit to develop new grain refiners. Herein refining role was elucidated by the first principles calculations based on adsorption behavior of a Mg atom on the closest-packed planes of grain refiners (Zr (001), Al2Y(311) and Al4C3(102)). Taking into account different sites, the site with the maximum adsorption energy value generally corresponded to the most possible location. The adsorption energy results show that the possible refining turn follows Al4C3(102)>Zr (001)>Al2Y(311). Meanwhile, the structural optimization confirmed that the Mg atom connected with two C atoms on the top of zig-zag plane of Al4C3(102), three Zr atoms at the hcp position on Zr (001), and two Y atoms and one Al atom at the bottom of zig-zag plane of Al2Y(311). The density of states revealed that the variation of d-orbital electrons of Mg atom became apparent during adsorption process. The values of Mulliken charges were 0.898 e in Al4C3(102), 0.410 e in Zr (001) and 0.245 e in Al2Y(311), respectively. This tendency agrees well with the previous experimental results. It indicates the adsorption energy on the closest-packed planes can be regarded as a prerequisite to select new grain refiners for Mg alloys in future.

First-Principles Study of Nanofacet Formation on 4H-SiC(0001) Surface

2014 ◽  
Vol 778-780 ◽  
pp. 201-205
Author(s):  
Keisuke Sawada ◽  
Jun Ichi Iwata ◽  
Atsushi Oshiyama
Keyword(s):  
Surface Energy ◽  
Total Energy ◽  
First Principles ◽  
Atomic Layer ◽  
First Principles Calculations ◽  
Atomic Structures ◽  
First Principles Study ◽  
Energy Variation ◽  
The Difference ◽  
Facet Formation

We perform the first-principles calculations on the 4H-SiC(0001) surface and clarify the mechanism of the facet formation. We first identify atomic structures of single-, double- and quadribilayer steps and find that the single-bilayer (SB) step has the lowest total energy among these three step structures. Then, we reveal that the nanofacet consisting of SB steps is more energetically stable than the equally spaced SB step and the surface-energy variation caused by the difference of stacking sequences of the bi-atomic layer near the surface is an important factor of the facet formation.

scholarly journals Adsorption sensitivity of graphane decorated with B, N, S, and Al towards HCN: a first-principles study

RSC Advances ◽  
2017 ◽  
Vol 7 (69) ◽  
pp. 43521-43530 ◽  
Author(s):  
Qingxiao Zhou ◽  
Weiwei Ju ◽  
Xiangying Su ◽  
Yongliang Yong ◽  
Xiaohong Li ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Adsorption Energy ◽  
Geometric Structure ◽  
First Principles ◽  
First Principles Calculations ◽  
First Principles Study ◽  
Hydrogenated Graphene

The geometric structure, adsorption energy, electronic structure, and magnetic properties of hydrogenated graphene (graphane) with the adsorption of a HCN molecule were investigated by first-principles calculations.

Density Functional Theory Study of the Adsorption of Metal Adatoms on Graphene

2021 ◽  
Vol 1016 ◽  
pp. 1863-1868
Author(s):  
Norio Nunomura ◽  
Jun Yamashita ◽  
Satoshi Sunada
Keyword(s):  
Density Functional Theory ◽  
Adsorption Energy ◽  
Copper Atom ◽  
First Principles ◽  
Density Functional ◽  
Aluminum Atom ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Nanocarbon Materials ◽  
The Difference

In this study, we investigated the influence of the interaction between graphene and other materials as a basis for controlling the electronic structure of nanocarbon materials. First-principles calculations based on density functional theory (DFT) were performed on the optimized structure, adsorption energies and electronic states when copper and aluminum atoms were placed on graphene. As a result, we found that copper and aluminum are stable at the bridge and the hollow site, respectively. It was found that the adsorption energy of aluminum atom on graphene is larger than that of copper atom. It is considered that the difference in adsorption energy is caused by the difference in the dominant electron orbitals of the copper atom and the aluminum atom.

Coverage-Dependent CO Adsorption Energy from First-Principles Calculations

2009 ◽  
Vol 113 (15) ◽  
pp. 6088-6092 ◽  
Author(s):  
Bin Shan ◽  
Yujun Zhao ◽  
Jangsuk Hyun ◽  
Neeti Kapur ◽  
John B. Nicholas ◽  
...  
Keyword(s):  
Adsorption Energy ◽  
First Principles ◽  
Co Adsorption ◽  
First Principles Calculations

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 Elastic Properties of the Nickel-Based L12 Intermetallics

1995 ◽  
Vol 408 ◽  
Author(s):  
D. Iotova ◽  
N. Kioussis ◽  
S. P. Lim ◽  
S. Sun ◽  
R. Wu
Keyword(s):  
Electronic Structure ◽  
Total Energy ◽  
Ab Initio ◽  
Elastic Properties ◽  
Elastic Constants ◽  
First Principles ◽  
Anisotropy Factor ◽  
Full Potential ◽  
First Principles Calculations ◽  
Linear Muffin Tin Orbital

AbstractThe elastic constants of the L12-type ordered nickel-based intermetallics Ni3X (X = Mn, Al, Ga, Si, Ge), have been calculated by means of ab initio total-energy electronic structurecalculations based on the full-potential linear-muffin-tin-orbital (FLMTO) method. Theorigins in the electronic structure of the variation of the elastic constants, bulk and shearmoduli are investigated across the series, and the effects of the anisotropy of bonding chargedensity on the shear anisotropy factor and the degree of ductility is discussed.

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