Site Preference of Refractory Elements in Ni-Based Single-Crystal Superalloys Alloying with Ru: From First Principles

2012 ◽  
Vol 554-556 ◽  
pp. 3-12
Author(s):  
Jian Jun Cui ◽  
Fei Sun ◽  
Jian Xin Zhang
Keyword(s):  
Binding Energy ◽  
Single Crystal ◽  
First Principles ◽  
First Principles Calculation ◽  
Partial Density ◽  
Site Preference ◽  
Strengthening Effect ◽  
Mulliken Population ◽  
Calculation Results ◽  
Partitioning Behavior

A first principles calculation method was used to investigate the site preference of Ruthenium (Ru) at the γ/γ′ interface in Ni-based single-crystal superalloys. The calculation results show that the addition of Ru can decrease the total energy and the binding energy of γ/γ′ interface, which may result in an improved microstructure stability of Ni-based single-crystal superalloys. Moreover, by calculation, it is also found that Ru can stabilize both γ and γ′ phases and have a preference for Ni site at the coherent γ/γ′ interface. When Ru substitutes the central Ni at the γ/γ′ interface, a reverse partitioning of W, Re and Cr occurs; while the partitioning behavior of Mo is not affected. The influence of Ru on the partitioning behavior of W, Re and Cr in γ′-Ni3Al was studied by Dmol3 calculation as well. The calculation results show that W, Re and Cr have a preference for Ni site in γ′- Ni3Al with Ru alloying. When Ru substitutes the central Ni atom, the site preference of W, Re and Cr varies accordingly. Furthermore, electronic structure analysis of γ/γ′ interface and γ′-Ni3Al in terms of Mulliken population and partial density of states (PDOS) was performed to understand the alloying mechanism of Ru in Ni-based single-crystal superalloys. The results show that the strengthening effect of Ru alloying is mainly due to the reduction in binding energy of Ru as well as a p-orbital hybridization between Ru and the host atoms.

scholarly journals First-principles Study on the Structure and Hydrogen Storage Properties of Na decorated BN sheet

2001 ◽  
Vol 71 (3) ◽  
pp. 580-587
Author(s):  
An Bo
Keyword(s):  
Hydrogen Storage ◽  
First Principles ◽  
First Principles Calculation ◽  
Partial Density ◽  
Hydrogen Storage Material ◽  
Mulliken Population ◽  
Hydrogen Storage Properties ◽  
Hydrogen Molecules ◽  
Storage Rate ◽  
Storage Properties

The Na decorated BN sheets have a stable sandwich structure and can be regarded as an excellent hydrogen storage material. With respect to first-principles calculation, the electronic structure, geometric structure, partial density of states, mulliken population and ability of absorbing hydrogen molecules of the Na decorated BN sheet have been investigated. The results show that: (1) The most stable structure is Na atom adsorption on the top of N atom, it has the greatest binding energy. (2) Na decorated BN sheet can adsorb twelve H2 molecules and the average adsorption energy is 0.530 eV/H2. (3) The hydrogen storage rate of Na decorated BN sheet is about 8.943wt%. (4) The adsorbed H2 molecules have polarization phenomenon.

Search for Effective Sites of Proximity Gettering Induced by Ion Implantation in Si Wafers with First Principles Calculation

2015 ◽  
Vol 242 ◽  
pp. 271-276
Author(s):  
Sho Shirasawa ◽  
Koji Sueoka
Keyword(s):  
Heat Treatment ◽  
Binding Energy ◽  
Ion Implantation ◽  
Point Defects ◽  
First Principles ◽  
First Principles Calculation ◽  
Manufacturing Processes ◽  
Intrinsic Point Defects

Fe, Ni and Cu atoms diffuse very quickly in Si and are the main targets for metal gettering. W, Hf, and Mo atoms, for example, which diffuse very slowly in Si have also recently become gettering targets in addition to these metals. Therefore, proximity gettering techniques by using ion implantation are being considered. Not only implanted elements but intrinsic point defects exist and form several complexes after the heat treatment for Si crystal recovery. This research systematically investigated the binding energy of twelve important metals (Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Hf, Ta, and W) with implanted dopants (B, C, P, and As) and their complexes with intrinsic point defects (vacancies (Vs) and self-interstitials (Is)) by using first principles calculation. These data should be useful in the design of proximity gettering in LSI manufacturing processes.

The Site Preference of Alloying Element Zr in NiAl Dislocation Core and its Effects on Bond Characters

2013 ◽  
Vol 344 ◽  
pp. 19-26
Author(s):  
Li Qun Chen ◽  
Zheng Chen Qiu
Keyword(s):  
Binding Energy ◽  
Edge Dislocation ◽  
Dislocation Core ◽  
Dislocation Motion ◽  
Partial Density ◽  
Site Preference ◽  
Alloying Element ◽  
Dislocation Interaction ◽  
High Temperature Alloys ◽  
Potential Applications

NiAl is one kind of high-temperature alloys with broad potential applications in aerospace industry. Its mechanical properties are believed to be largely related to the dislocation behavior and impurity-dislocation interaction. In the paper we report first principles study of the alloying effect of Zr in the [10(010) edge dislocation core of NiAl. The binding energy of doping system decreases 3.77 eV when a Zr atom substituted for an Al, only decreases 1.06 eV with substitution for a Ni atom. The result of the binding energy shows that a Zr atom prefers to occupy an Al site in the dislocation core of NiAl. The analyses of the charge distribution, the interatomic energy and the partial density of states suggest that Zr will greatly enhance the interaction between Zr atom and neighboring host atoms, as well as that between host atoms. These results show that the alloying element Zr induced pinning effect on the edge dislocation motion is predicted, and could be helpful for understanding microscopic mechanisms of alloying-induce hardening in NiAl alloy.

Adsorption of Methane on Pristine and Al-Doped Graphene: A Comparative Study via First-Principles Calculation

2012 ◽  
Vol 602-604 ◽  
pp. 870-873 ◽  
Author(s):  
Wei Zhao ◽  
Qing Yuan Meng
Keyword(s):  
Charge Transfer ◽  
Binding Energy ◽  
Comparative Study ◽  
First Principles ◽  
First Principles Calculation ◽  
Pristine Graphene ◽  
First Principles Calculations ◽  
Graphene Surface ◽  
Doped Graphene ◽  
Adsorption Of Methane

The adsorption of methane (CH4) molecule on the pristine and Al-doped (4, 8) graphene was investigated via the first-principles calculations. The results demonstrated that, in comparison to the adsorption of a CH4molecule on the pristine graphene sheet, a relatively stronger adsorption was observed between the CH4molecule and Al-doped graphene with a shorter adsorption distance, larger binding energy and more charge-transfer from the graphene surface to the CH4molecule. Therefore, the Al-doped graphene can be expected to be a novel sensor for the detection of CH4molecules in future applications.

Investigation of Electronic Structures of F-Doped TiO2 by First-Principles Calculation

2009 ◽  
Vol 620-622 ◽  
pp. 647-650 ◽  
Author(s):  
Ying Cui ◽  
Hao Du ◽  
Li Shi Wen
Keyword(s):  
Photocatalytic Activity ◽  
First Principles ◽  
Electronic Structures ◽  
Lower Energy ◽  
Anatase Tio2 ◽  
First Principles Calculation ◽  
Visible Light Region ◽  
Doped Tio2 ◽  
Light Region ◽  
Calculation Results

F-doped TiO2 has exhibited superior photocatalytic activity. However, its electronic structures and photocatalysis mechanism are still unclear. In the present work, the structural optimization and electronic structure of F-doped anatase TiO2 have been investigated by means of the first-principles pseudopotential total energy method. It has been demonstrated that F doping would modify the valence band at the lower energy direction in the F-doped TiO2. Calculation results confirm that doping of fluorine would not shift the absorption edge into the visible light region. Instead, we attributed its photocatalytic activity to the enhancement of the oxidative power of F-doped TiO2.

scholarly journals First-Principles Investigation on Electrochemical Performance of Na-Doped LiNi1/3Co1/3Mn1/3O2

2021 ◽  
Vol 8 ◽  
Author(s):  
Yumei Gao ◽  
Kaixiang Shen ◽  
Ping Liu ◽  
Liming Liu ◽  
Feng Chi ◽  
...  
Keyword(s):  
Potential Energy ◽  
Electrochemical Performance ◽  
Cathode Material ◽  
First Principles ◽  
Density Functional ◽  
Lithium Ion ◽  
Partial Density ◽  
Performance Study ◽  
Na Doping ◽  
Calculation Results

The cathode material LiNi1/3Co1/3Mn1/3O2 for lithium-ion battery has a better electrochemical property than LiCoO2. In order to improve its electrochemical performance, Na-doped LiNi1/3Co1/3Mn1/3O2 is one of the effective modifications. In this article, based on the density functional theory of the first-principles, the conductivity and the potential energy of the Na-doped LiNi1/3Co1/3Mn1/3O2 are calculated with Materials Studio and Nanodcal, respectively. The calculation results of the band gap, partial density of states, formation energy of intercalation of Li+, electron density difference, and potential energy of electrons show that the new cathode material Li1−xNax Ni1/3Co1/3Mn1/3O2 has a better conductivity when the Na-doping amount is x = 0.05 mol. The 3D and 2D potential maps of Li1−xNaxNi1/3Co1/3Mn1/3O2 can be obtained from Nanodcal. The maps demonstrate that Na-doping can reduce the potential well and increase the removal rate of lithium-ion. The theoretical calculation results match well with experimental results. Our method and analysis can provide some theoretical proposals for the electrochemical performance study of doping. This method can also be applied to the performance study of new optoelectronic devices.

scholarly journals Robust Spin-Gapless Behavior in the Newly Discovered Half Heusler Compound MnPK

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3117 ◽  
Author(s):  
Jiaxue You ◽  
Jieting Cao ◽  
Rabah Khenata ◽  
Xiaotian Wang ◽  
Xunan Shen ◽  
...  
Keyword(s):  
First Principles ◽  
Experimental Studies ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Good Resistance ◽  
Heusler Compound ◽  
New Class ◽  
Hubbard U ◽  
Calculation Results ◽  
Spin Gapless Semiconductors

Spin gapless semiconductors have aroused high research interest since their discovery and a lot of effort has been exerted on their exploration, in terms of both theoretical calculation and experimental verification. Among different spin gapless materials, Heusler compounds stand out thanks to their high Curie temperature and highly diverse compositions. Especially, both theoretical and experimental studies have reported the presence of spin gapless properties in this kind of material. Recently, a new class of d0 − d Dirac half Heusler compound was introduced by Davatolhagh et al. and Dirac, and spin gapless semiconductivity has been successfully predicted in MnPK. To further expand the research in this direction, we conducted a systematical investigation on the spin gapless behavior of MnPK with both generalized gradient approximation (GGA) and GGA + Hubbard U methods under both uniform and tetragonal strain conditions by first principles calculation. Results show the spin gapless behavior in this material as revealed previously. Different Hubbard U values have been considered and they mainly affect the band structure in the spin-down channel while the spin gapless feature in the spin-up direction is maintained. The obtained lattice constant is very well consistent with a previous study. More importantly, it is found that the spin gapless property of MnPK shows good resistance for both uniform and tetragonal strains, and this robustness is very rare in the reported studies and can be extremely interesting and practical for the final end application. This study elaborates the electronic and magnetic properties of the half Heusler compound MnPK under uniform and tetragonal strain conditions, and the obtained results can give a very valuable reference for related research works, or even further motivate the experimental synthesis of the relative material.

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