First-principles study of the vacancy and layer defects in Ti3SiC2

First-principles calculations are performed to study the effects of defect on the structure and electronic properties of Ti3SiC2. The calculations show that the formation energy of Si vacancy is minimal compared with the Ti or C vacancies in Ti3SiC2. The defects of Si layer also can be formed under high-temperature or irradiation environments. The C-layers or Ti-layers are almost impossible to form. If the Si vacancy or Si layers are formed, they prefer to be substituted by the O and H atoms to form the MXene structure, and the unit cell of Ti3SiC2 lattice constant decreases in c-direction. However, it has quite slight effect on electronic properties of Ti3SiC2. The He impurities are almost impossible to occupy the Si vacancies, because the formation energy are 50.860 eV for one layer of Si atoms substituted by the He atoms. This type of defect leads to the lattice constant of Ti3SiC2 in c-direction increasing considerably. Therefore, Ti3SiC2 is a suitable candidate for nuclear materials because of the high-formation energies of He impurities under irradiation environment.

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Formation energy, mechanical and electronic properties of buckled heptazine (C6N8) sheet: First-principles calculations

Computational Condensed Matter ◽

10.1016/j.cocom.2021.e00619 ◽

2021 ◽

pp. e00619

Author(s):

Yusuf Zuntu Abdullahi

Keyword(s):

Electronic Properties ◽

First Principles ◽

Formation Energy ◽

First Principles Calculations

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Magnetic and electronic properties of Mn2Sn thin films: First-principles calculations and high temperature series expansions

Chinese Journal of Physics ◽

10.1016/j.cjph.2018.08.023 ◽

2018 ◽

Vol 56 (5) ◽

pp. 1985-1989 ◽

Cited By ~ 5

Author(s):

R. Masrour ◽

E.K. Hlil ◽

A. Jabr ◽

M. Hamedoun ◽

A. Benyoussef ◽

...

Keyword(s):

Thin Films ◽

High Temperature ◽

Electronic Properties ◽

First Principles ◽

Temperature Series ◽

Series Expansions ◽

First Principles Calculations

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First Principles Calculations on Elastic, Thermodynamic and Electronic Properties of Co2Zr and Co2Ti at High Temperature and Pressure

Applied Sciences ◽

10.3390/app10062097 ◽

2020 ◽

Vol 10 (6) ◽

pp. 2097

Author(s):

Mi-An Xue ◽

Xiaoli Yuan ◽

Cheng Zhong ◽

Peng Wan

Keyword(s):

High Temperature ◽

Electronic Properties ◽

Debye Temperature ◽

First Principles ◽

Density Functional ◽

Debye Model ◽

First Principles Calculations ◽

Generalized Gradient ◽

High Temperature And Pressure ◽

Temperature And Pressure

Co2Zr and Co2Ti are both cubic crystals with a Cu2Mg-type structure. The elastic, thermodynamic and electronic properties of the intermetallic compounds Co2Zr and Co2Ti are investigated by using ab initio plane-wave pseudopotential density functional theory (PWPDFT) and generalized gradient approximation (GGA) under high temperature and pressure. The partially calculated results are consistent with the available experimental data. The elastic properties of Co2Zr and Co2Ti under high pressure were first studied by first principles calculations. The results indicate that the elastic constants, elastic modulus and Poisson’s ratio are functions of pressure, indicating that the effect of pressure on the ductility and anisotropy is significant. The thermodynamic properties are also calculated by the quasi-harmonic Debye model. In the range of 0~100 GPa pressure and 0~1500 K temperature, the Debye temperature Θ, the heat capacity CV and the thermal expansion α vary with pressure and temperature. Co2Ti has a higher Debye temperature than Co2Zr under the same pressure. Decreasing temperature and increasing pressure have the same effects on CV and α. The electron density difference and density of states of Co2Zr and Co2Ti are finally investigated. The results show that both Co2Zr and Co2Ti are typically metal crystals but Co2Zr has greater covalence than Co2Ti.

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First principles study of defects in solid electrolyte lithium thiophosphate Li7P3S11

MRS Proceedings ◽

10.1557/opl.2011.1423 ◽

2011 ◽

Vol 1331 ◽

Author(s):

Ka Xiong ◽

Weichao Wang ◽

Roberto Longo Pazos ◽

Kyeongjae Cho

Keyword(s):

Electronic Structure ◽

Solid Electrolyte ◽

Band Gap ◽

Electronic Properties ◽

First Principles ◽

Wide Band ◽

Ion Conductivity ◽

First Principles Calculations ◽

Wide Band Gap ◽

Formation Energies

ABSTRACTWe investigate the electronic structure of interstitial Li and Li vacancy in Li7P3S11 by first principles calculations. We find that Li7P3S11 is a good insulator with a wide band gap of 3.5 eV. We find that the Li vacancy and interstitial Li+ ion do not introduce states in the band gap hence they do not deteriorate the electronic properties of Li7P3S11. The calculated formation energies of Li vacancies are much larger than those of Li interstitials, indicating that the ion conductivity may arise from the migration of interstitial Li.

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

MRS Proceedings ◽

10.1557/proc-364-1265 ◽

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.

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Structural, elastic and electronic properties and formation energies for hexagonal (W0.5Al0.5)C in comparison with binary carbides WC and Al4C3 from first-principles calculations

Physica B Condensed Matter ◽

10.1016/j.physb.2008.01.045 ◽

2008 ◽

Vol 403 (17) ◽

pp. 2654-2661 ◽

Cited By ~ 21

Author(s):

D.V. Suetin ◽

I.R. Shein ◽

A.L. Ivanovskii

Keyword(s):

Electronic Properties ◽

First Principles ◽

First Principles Calculations ◽

Formation Energies

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FIRST-PRINCIPLES STUDY OF OXYGEN-VACANCY Cu2O (111) SURFACE

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633612500848 ◽

2012 ◽

Vol 11 (06) ◽

pp. 1261-1280 ◽

Cited By ~ 5

Author(s):

HUANWEN WU ◽

NING ZHANG ◽

HONGMING WANG ◽

SANGUO HONG

Keyword(s):

Oxygen Vacancy ◽

Electronic Properties ◽

First Principles ◽

Electronic Structures ◽

Oxygen Vacancies ◽

Vacancy Formation ◽

First Principles Calculations ◽

First Principles Study ◽

Formation Energies ◽

Geometric And Electronic Properties

Geometric and electronic properties and vacancy formation energies for two kinds of oxygen-vacancy Cu 2 O (111) surfaces have been investigated by first-principles calculations. Results show that the relaxation happens mainly on the top three trilayers of surfaces. Two vacancies trap electrons of -0.11e and -0.27e, respectively. The effects of oxygen vacancies on the electronic structures are found rather localized. The electronic structures suggest that the oxygen vacancies enhance the electron donating ability of the surfaces to some extent. The energies of 1.75 and 1.43 eV for the formation of oxygen vacancies are rather low, which indicates the partially reduced surfaces are stable and easy to produce.

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Defect formation of CuI-doped by group-IIB elements

Modern Physics Letters B ◽

10.1142/s0217984918504237 ◽

2019 ◽

Vol 33 (01) ◽

pp. 1850423

Author(s):

Hui Chen ◽

Mu Gu

Keyword(s):

First Principles ◽

Formation Energy ◽

Defect Formation ◽

Valence Band Maximum ◽

Acceptor Level ◽

First Principles Calculations ◽

Transition Energies ◽

Band Maximum ◽

P Type ◽

Formation Energies

First-principles calculations have been performed to investigate the doping defects in CuI with group-IIB elements such as Zn, Cd and Hg. The calculated transition energies for substitutional Zn, Cd and Hg are 1.32, 1.28 and 0.60 eV, respectively. These group-IIB elements at the substitutional sites complex with a copper vacancy [Formula: see text] have the lower formation energies as compared to dopants located at the substitutional sites or interstitial sites, respectively. Among all the complex defects considered, [Formula: see text] has the lowest formation energy and it induces the acceptor level [Formula: see text] eV above the valence-band maximum (VBM), which is close to the acceptor level [Formula: see text] eV of [Formula: see text], suggesting that Hg may be a good dopant for CuI to improve its p-type conductivity.

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First-principles investigation of the vacancy-related properties of Ta2AlC

Modern Physics Letters B ◽

10.1142/s0217984919502099 ◽

2019 ◽

Vol 33 (18) ◽

pp. 1950209

Author(s):

Jitao Liu ◽

Zhaocang Meng ◽

Jiajia Liu ◽

Xiaolu Zhu ◽

Canglong Wang ◽

...

Keyword(s):

High Temperature ◽

First Principles ◽

Formation Energy ◽

Vacancy Formation ◽

Clear Effect ◽

Formation Energies ◽

Nuclear Applications ◽

First Principles Method

The formation energies and formation volumes of the Ta, Al, and C vacancies in Ta2AlC have been calculated by using first-principles method. The results have shown that the vacancy formation is energetically most favorable for the C atom with formation energy of 1.72 eV. The formation energies of Ta and Al vacancies are 3.44 eV and 3.52 eV, respectively. The electronics properties show that the Ta vacancy has a clear effect on the conductivity of the Ta2AlC. This result indicates that Ta2AlC is a good candidate material for high-temperature and nuclear applications.

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