Theoretical Investigation on Microstructure of the Novel 24R-Type LPSO Phase in Mg97Zn1Y2 Alloy

2011 ◽  
Vol 233-235 ◽  
pp. 2359-2366
Author(s):  
Ping Ying Tang ◽  
Meng Xue Zeng ◽  
Dong Lin Li ◽  
Bi Yu Tang ◽  
Li Ming Peng ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Stacking Fault ◽  
First Principles Calculation ◽  
The Novel ◽  
Ordered Structure ◽  
Density Of State ◽  
Electronic Density ◽  
Functional Theory ◽  
Long Period

The first-principles calculation based on density functional theory has been carried out to study the microstructural feature of the novel 24R-type long period stacking ordered structure in Mg97Zn1Y2alloy. The lattice positions of the Y and Zn atoms are determined theoretically, it is shown that the additive atoms are firstly enriched in the stacking fault layers at the two ends, a small amount are distributed in the interior stacking fault layers of the structure. And the arrangement of these Y and Zn atoms trends to be along the diagonal line of the unit cell. The structural stability is analyzed and the electronic density of state is discussed as well as.

scholarly journals Strain Conditions for the Inverse Heusler Type Fully Compensated Spin-Gapless Semiconductor Ti2MnAl: A First-Principles Study

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2091 ◽  
Author(s):  
Tie Yang ◽  
Liyu Hao ◽  
Rabah Khenata ◽  
Xiaotian Wang
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Debye Model ◽  
Pressure Effects ◽  
First Principles Calculation ◽  
Strain Condition ◽  
Functional Theory ◽  
Future Work

In this work, we systematically studied the structural, electronic, magnetic, mechanical and thermodynamic properties of the fully compensated spin-gapless inverse Heusler Ti2MnAl compound under pressure strain condition by applying the first-principles calculation based on density functional theory and the quasi-harmonic Debye model. The obtained structural, electronic and magnetic behaviors without pressure are well consistent with previous studies. It is found that the spin-gapless characteristic is destroyed at 20 GPa and then restored with further increase in pressure. While, the fully compensated ferromagnetism shows a better resistance against the pressure up to 30 GPa and then becomes to non-magnetism at higher pressure. Tetragonal distortion has also been investigated and it is found the spin-gapless property is only destroyed when c/a is less than 1 at 95% volume. Three independent elastic constants and various moduli have been calculated and they all show increasing tendency with pressure increase. Additionally, the pressure effects on the thermodynamic properties under different temperature have been studied, including the normalized volume, thermal expansion coefficient, heat capacity at constant volume, Grüneisen constant and Debye temperature. Overall, this theoretical study presents a detailed analysis of the physical properties’ variation under strain condition from different aspects on Ti2MnAl and, thus, can provide a helpful reference for the future work and even inspire some new studies and lead to some insight on the application of this material.

scholarly journals First-Principles Calculation of Conductivity of Ce-C Codoped SnO2 Contacts

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Can Ding ◽  
Zhenjiang Gao ◽  
Xing Hu ◽  
Zhao Yuan
Keyword(s):  
Charge Density ◽  
Lattice Constant ◽  
First Principles ◽  
Density Functional ◽  
Energy Levels ◽  
Circuit Breaker ◽  
Enthalpy Change ◽  
First Principles Calculation ◽  
Contact Material ◽  
Electronic Density

The contact is the core element of the vacuum interrupter of the mechanical DC circuit breaker. The electrical conductivity and welding resistance of the material directly affect its stability and reliability. AgSnO2 contact material has low resistivity, welding resistance, and so on. This material occupies an important position of the circuit breaker contact material. This research is based on the first-principles analysis method of density functional theory. The article calculated the lattice constant, enthalpy change, energy band, electronic density of state, charge density distribution, population, and conductivity of Ce, C single-doped, and Ce-C codoped SnO2 systems. The results show that Ce, C single doping, and Ce-C codoping all increase the cell volume and lattice constant. When the elements are codoped, the enthalpy change is the largest, and the thermal stability is the best. It has the smallest bandgap, the most impurity energy levels, and the least energy required for electronic transitions. The 4f orbital electrons of the Ce atom and the 2p orbital electrons of C are the sources of impurity energy near the Fermi level. When the elements are codoped, more impurity energy levels are generated at the bottom of the conduction band and the top of the valence band. Its bandgap is reduced so conductivity is improved. From the charge density and population analysis, the number of free electrons of Ce atoms and C atoms is redistributed after codoping. It forms a Ce-C covalent bond to further increase the degree of commonality of electrons and enhance the metallicity. The conductivity analysis shows that both single-doped and codoped conductivity have been improved. When the elements are codoped, the conductivity is the largest, and the conductivity is the best.

Electronic and structural study of hexagonal TiC nanowires: ab initio study

BIBECHANA ◽  
2018 ◽  
Vol 16 ◽  
pp. 7-14 ◽  
Author(s):  
Puspa Raj Adhikari ◽  
Om Prakash Upadhyay ◽  
Gopi Chandra Kaphle ◽  
Anurag Srivastava
Keyword(s):  
Density Functional ◽  
Small Diameter ◽  
Hexagonal Structure ◽  
Density Of State ◽  
Electronic Density ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
The One ◽  
The Impact ◽  
Bulk Structures

Nanowire are the one-dimensional nanostructure with the diameter order of one to few hundred nanometre. These structure shows unique properties other than their bulk structures. In this article, a qualitative first principle discussion of TiC nanowire is reported, indicating the impact of DFT based GGA relativistic corrections on its electronic properties. Here, we analyse   the Titanium Carbide (TiC) nanowire of hexagonal structure periodic in Z-direction with the density functional theory (DFT). The GGA with RBBE Correlation analysis of this material shows the metallic characteristics in its bulk but the electronic density of  state shows that the hybridization state are different from their bulk when the material is analysed in nanostructure form. Three structures of hexagonal TiC nanowire directed in (1,1,1) plane were analysed to explore diameter (4-18) Å dependent comparative study of electronic, stabilizing and optical property which shows unique different result counterparts to its bulk. Hexagonal TiC nanowire were found to be semiconducting with narrow band gap (0.21-0.34) eV in small diameter while metallic in higher diameter. They are comparable stables as their bulk for higher structure. Similarly, for the same investigation, the structures are cross checked by surface atom passivation to verify the reliability of the result that we found.BIBECHANA 16 (2019) 7-14

First-principles investigations on the phase stability, elastic and thermodynamic properties of Zr–Al alloys

2015 ◽  
Vol 26 (12) ◽  
pp. 1550143 ◽  
Author(s):  
Leini Wang ◽  
Songjun Hou ◽  
Dewei Liang
Keyword(s):  
Thermodynamic Properties ◽  
Debye Temperature ◽  
Phase Stability ◽  
First Principles ◽  
Density Functional ◽  
Elastic Wave Velocity ◽  
Electronic Density ◽  
Functional Theory ◽  
High Bulk ◽  
Substitutional Alloys

In this paper, we employ first-principles methods based on electronic density functional theory (DFT) to investigate the phase stability, elastic and thermodynamic properties of Zr – Al binary substitutional alloys which are Zr 3 Al , Zr 2 Al , ZrAl , ZrAl 2 and ZrAl 3. By analyzing the elastic constants and enthalpy of formation, those phases both satisfy the generalized stability criteria and the results show that ZrAl 2 is the most stable. Due to high bulk modulus B, shear modulus G and Youngs modulus Y, ZrAl 2 also possesses excellent mechanical properties. Moreover, it is expected that there will be covalent bonding between Zr and Al atom in ZrAl 2 compound, which is confirmed by the electronic structure and the differences of charge density discussions. In the end, based on the calculated elastic modulus, the elastic wave velocity, Debye temperature ΘD and specific heat CV are discussed. As a result, ZrAl 3 possesses the highest Debye temperature and sound velocity, meaning a larger associated thermal conductivity and higher melting temperature.

First-Principles Calculation of Water Molecules with Adsorbed Ions on the Fe(001) Surface

2010 ◽  
Vol 654-656 ◽  
pp. 1662-1665
Author(s):  
Norio Nunomura ◽  
Satoshi Sunada
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Dissociative Adsorption ◽  
First Principles Calculation ◽  
Water Molecules ◽  
Metal Interface ◽  
Functional Theory ◽  
Atomic Orbitals ◽  
Adsorption Structure ◽  
Valence Electrons

The behavior of water molecules with sulfate on the Fe(001) surface has been investigated using a first-principles method based on density-functional theory (DFT) with numerical atomic orbitals as basis functions for the description of valence electrons and nonlocal pseudopotentials for the atomic core. We present results for the adsorption structure and the bonding nature as caused by the adsorption-induced variations in the electron density and the projected density of states. We have found that the structure of absorbed sulfate depends on the coverage of water molecule on the surface. Analysis of electrostatic potential at an aqueous metal interface provides an appropriate framework to understand complicated potential structures. The mechanism of proton transfer through dissociative adsorption and hydrogen bonding of water molecules has been obtained from calculated results.

First Principles Study on Structural and Electronic Properties of LiFeSO4OH Cathode Material for Lithium Ion Batteries

2014 ◽  
Vol 510 ◽  
pp. 33-38 ◽  
Author(s):  
F.W. Badrudin ◽  
M.S.A. Rasiman ◽  
M.F.M. Taib ◽  
N.H. Hussin ◽  
O.H. Hassan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Cathode Material ◽  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Electronic Conductivity ◽  
Lithium Ion ◽  
Density Of State ◽  
Functional Theory ◽  
Structural And Electronic Properties

Structural and electronic properties of a new fluorine-free cathode material of polyanionichydroxysulfates, LiFeSO4OH withcaminitestructure are studied using first principles density functional theory. From the calculated result, it reveals that antiferromagnetic configuration is more stable compared to ferromagnetic and non-magnetic configuration. Meanwhile, the density of state calculation divulges that this material exhibited large d-d type of band gap and would behave as a Mott-Hubbard insulator. Thus, this behaviour can lead to poor electronic conductivity.

THE Ge(001) SURFACE RECONSTRUCTION: DFT AND MCS

1999 ◽  
Vol 06 (06) ◽  
pp. 1045-1051 ◽  
Author(s):  
YOSHIHIDE YOSHIMOTO ◽  
YOSHIMICHI NAKAMURA ◽  
HIROSHI KAWAI ◽  
MASARU TSUKADA ◽  
MASATOSHI NAKAYAMA
Keyword(s):  
Phase Transition ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Transient Temperature ◽  
Diffraction Experiment ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Flip Flop ◽  
X Ray

The problem of relative energetic stabilities of the high order reconstructions of the Ge(001) surface is revisited by a more refined first-principles calculation based on density functional theory. Using this result, we performed a Monte Carlo simulation of the phase transition, and obtained 315 K as the transition temperature of p(2× 1) → c(4× 2). This reproduces fairly well the transient temperature (250–350 K) observed by an X-ray diffraction experiment. The obtained geometry of the c(4× 2) structure compares well with an X-ray diffraction experiment. The potential energy curves of flip-flop motions of both single dimer and dimer in type-P defect are also obtained.

First Principles Studies on Structural, Electronic and Optical Properties of SnO2

2014 ◽  
Vol 900 ◽  
pp. 203-208 ◽  
Author(s):  
Ting Ting Shao ◽  
Fu Chun Zhang ◽  
Wei Hu Zhang
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Optical Properties ◽  
Plane Wave ◽  
Qualitative Analysis ◽  
First Principles ◽  
Density Functional ◽  
Density Of State ◽  
Functional Theory ◽  
Electronic And Optical Properties

The structural, electronic, and optical properties of rutile-type SnO2 are studied by plane-wave pseudopotential density functional theory (DFT) with GGA, LDA, B3LYP and PBE0 respectively. The computing results show that the band gap getting from PBE0 and B3LYP is much more consistent with the available experimental data than that from GGA and LDA, no matter what the latter use ultra-soft pseudopotential or norm conserving pseudopotential. However, the density of state, real part and imaginary part of dielectric function calculating from every type is basically similar in qualitative analysis.

First principles study of the adsorption and dissociation mechanisms of H2S on a TiO2anatase (001) surface

RSC Advances ◽  
2016 ◽  
Vol 6 (10) ◽  
pp. 7941-7949 ◽  
Author(s):  
Naeem Shahzad ◽  
Akhtar Hussain ◽  
Naeem Mustafa ◽  
Nisar Ali ◽  
Mohammed Benali Kanoun ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Functional Theory ◽  
P Adsorption ◽  
First Principles Study ◽  
The Density Functional Theory ◽  
Dissociation Mechanisms ◽  
Adsorption And Dissociation

Adsorption and dissociation mechanisms of H2S on a TiO2(001) surface were elucidated using first principles calculation based on the density functional theory.

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