First-Principles Calculation of Defect Formation and Positron Annihilation States in Bi2Te3

2017 ◽  
Vol 373 ◽  
pp. 41-45 ◽  
Author(s):  
Bin Zhao ◽  
Bo Zhou ◽  
Chong Yang Li ◽  
Ning Qi ◽  
Zhi Quan Chen
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Defect Formation ◽  
First Principles Calculation ◽  
Functional Theory ◽  
Rich Condition ◽  
The Density Functional Theory ◽  
Positron Wave Function ◽  
Positron Lifetimes

Defect formation energy in Bi2Te3 thermoelectric material was calculated using a first principles approach based on the Density Functional Theory (DFT). For vacancy-type defect, the Te1 vacancy (VTe1) is the most stable defect with low formation energy in both Bi-rich and Te-rich conditions, which indicates that the Te1 vacancies have higher probability to be formed. For antisite defects, the formation energy of BiTe1 is much lower than that of BiTe2 in Bi-rich condition, while in Te-rich condition it is beneficial for TeBi with lower formation energy. Positron wave function distribution and positron lifetimes of different annihilation states in Bi2Te3 were also calculated using the atomic superposition (ATSUP) method. The positron bulk lifetime in Bi2Te3 is about 231 ps, and for the neutral vacancy-type defects without relaxation, the positron lifetimes of VBi, VTe1 and VTe2 are 275 ps, 295 ps and 269 ps, respectively.

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.

Hydrogen Atom Adsorption on α-Al2O3(0001) Surface from First Principles

2011 ◽  
Vol 399-401 ◽  
pp. 2261-2265 ◽  
Author(s):  
Jian Gong Hu ◽  
Yi Sheng Zhang ◽  
Li Chao Jia ◽  
Bin Zhu ◽  
Hong Guang Yang ◽  
...  
Keyword(s):  
Adsorption Energy ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Large Decrease ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation ◽  
The Density Functional Theory ◽  
Low Coverage

First-principles calculation based on the density functional theory in the generalized gradient approximation was adopted to systematically investigate the α-Al2O3(0001) surface structure and the adsorption of H atom on the α-Al2O3(0001) surface. The calculations show that the O atop site is the energetically most favorable adsorption site at low coverage: at the H coverage of 1/6 ML (monolayer), the adsorption energy reaches up to7.61eV; in the regime of higher H coverages, the H atoms prefer to form atom cluster on the α-Al2O3(0001) surface, and the adsorption energy on the α-Al2O3(0001) with a pre-adsorbed H atom gets smaller, which illustrates that α-Al2O3that can prevent the penetration of hydrogen. With the increase of H coverage, the dipole moment reduces, which leads to a large decrease in the work function.

First-Principles Studies on the Component Dependences of High-Entropy Alloys

2011 ◽  
Vol 338 ◽  
pp. 380-383 ◽  
Author(s):  
Shao Qing Wang ◽  
Heng Qiang Ye
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Lattice Structure ◽  
First Principles Calculation ◽  
High Entropy Alloys ◽  
Functional Theory ◽  
High Entropy ◽  
Composition Variation ◽  
The Density Functional Theory

An elabrate study on the structrural and mechanical properties of the five-element FeNiCrCuCo high-entropy alloys is carried out by first-principles calculation within the density-functional theory. The combination application of plane-wave pseudopotentials and alchemical pseudoatom methods is realized to imitate the random elemental lattice occupation in the alloys. The dependence of composition variation to the crystallographic and thermodynamic properties of FeNiCrCuCo alloys in simple BCC and FCC lattices are investigated. The key role of chromium in strengthening the inter-atomic cohesion and stabilizing the lattice structure of HEAs is suggested.

FIRST-PRINCIPLES CALCULATION OF LEAD-FREE PEROVSKITE SnTiO3

2013 ◽  
Vol 27 (24) ◽  
pp. 1350144 ◽  
Author(s):  
HONGJUN YE ◽  
RUIZHI ZHANG ◽  
DAWEI WANG ◽  
YU CUI ◽  
JIE WEI ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Piezoelectric Materials ◽  
First Principles Calculation ◽  
Lead Free ◽  
Structure Stability ◽  
Functional Theory ◽  
Phonon Spectra ◽  
Sn Substitution

The phonon spectra, band structure and density of states of cubic perovskite SnTiO 3 were investigated using first-principles density functional theory (DFT) computation. The potential energy curves of cations displacement and the formation energy of Sn substitution to B-site were calculated to estimate the structure stability. The results indicate that perovskite SnTiO 3 is a promising ferroelectric end member for lead-free piezoelectric materials and applications.

Oxygen Vacancies in Amorphous HfO2 and SiO2

2008 ◽  
Vol 1073 ◽  
Author(s):  
Chioko Kaneta ◽  
Takahiro Yamasaki
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Gate Dielectrics ◽  
Propagation Mechanism ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
The Difference ◽  
Formation Energies

ABSTRACTFormation energies and electronic properties of oxygen vacancies in amorphous HfO2 gate dielectrics are investigated by employing the first-principles method based on the density functional theory. We have found that the formation energy of neutral oxygen vacancy in amorphous HfO2 distributes from 4.7 to 6.1 eV, most of which is lower than the value for cubic HfO2, 6.0 eV. We also investigated the stabilities of the Vo pairs in various charged state and compared with those in amorphous SiO2. We found that Vo++ is stabilized in the vicinity of Vo in SiO2. In HfO2, however, this does not happen. This suggests the difference of defect propagation mechanism in HfO2 and SiO2.

Theoretical Study of the Electronic Structures of Na-Doped ZnO

2014 ◽  
Vol 665 ◽  
pp. 124-127 ◽  
Author(s):  
Qi Xin Wan ◽  
Bi Lin Shao ◽  
Zhi Hua Xiong ◽  
Dong Mei Li ◽  
Guo Dong Liu
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Formation Energy ◽  
Theoretical Study ◽  
The Other ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Doped Zno

The first-principles with pseudopotentials method based on the density functional theory was applied to calculate the formation energy of impurities and the electronic structure of ZnO doped with Na. In Na-doped ZnO, NaOis the most unstable than the other cases. Simultaneously, NaZnis more stable than Naiaccording to that NaZnhave smaller formation energy. Furthermore, the electronic structure of Na-doped ZnO indicates that that NaZnbehaves as an acceptor, while Naibehaves as a donor.

scholarly journals Hydrogen Diffusion and Adsorption on WO3 (001) based on First Principles Calculation

2021 ◽  
Author(s):  
Pingguo Jiang ◽  
Xiangbiao Yu ◽  
Yiyu Xiao ◽  
Su Zhao ◽  
Wangjun Peng
Keyword(s):  
Adsorption Energy ◽  
First Principles ◽  
Density Functional ◽  
Hydrogen Diffusion ◽  
Hydrogen Reduction ◽  
Tungsten Powder ◽  
Production Equipment ◽  
First Principles Calculation ◽  
Functional Theory ◽  
The Density Functional Theory

Hydrogen reduction of tungsten oxide is currently the most widely applied ultrafine tungsten powder production process. The process has the advantage of short, pollution free and simple production equipment. But it is difficult to effectively control the morphology and particle size of the tungsten powder because of lacking in-depth understanding of the dynamic mechanism of the process. The first-principles calculations are carried out to explore the diffusion and internal adsorption of hydrogen on the WO-terminated surface of WO3 based on the density functional theory. The results show that hydrogen can diffuse from the WO terminal surface to the inside of WO3, the activation energy of diffusion is 46.682 Kcal/mol. It’s preferable for hydrogen to diffuse from the surface to the inside than diffuse within the WO3 lattice. The adsorption energy of hydrogen on the WO termination surface of WO3 is 15.093 Kcal/mol, the adsorption energy of hydrogen inside the WO termination surface of WO3 is 14.116 Kcal/mol, which means the hydrogen is easier to adsorb inside the WO3 lattice.

scholarly journals Bi2Te3 single crystals with high room-temperature thermoelectric performance enhanced by manipulating point defects based on first-principles calculation

RSC Advances ◽  
2019 ◽  
Vol 9 (25) ◽  
pp. 14422-14431 ◽  
Author(s):  
Chunmei Tang ◽  
Zhicheng Huang ◽  
Jun Pei ◽  
Bo-Ping Zhang ◽  
Peng-Peng Shang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Single Crystals ◽  
Point Defects ◽  
First Principles ◽  
Density Functional ◽  
Formation Energy ◽  
Room Temperature ◽  
First Principles Calculation ◽  
Functional Theory

This study prepared Bi2Te3 single crystals and investigated the thermoelectric properties of Bi2Te3 based on the electronic structure and formation energy of point defects which are calculated by density functional theory.

scholarly journals Electron-phonon interaction in In-induced √7 ×√3 structures on Si(111) from first-principles

2021 ◽  
Author(s):  
I. Yu. Sklyadneva ◽  
Rolf Heid ◽  
Pedro Miguel Echenique ◽  
Evgueni Chulkov
Keyword(s):  
Density Functional Theory ◽  
Double Layer ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Single Layer ◽  
Phonon Interaction ◽  
Functional Theory ◽  
Electron Phonon Interaction ◽  
The Density Functional Theory

Electron-phonon interaction in the Si(111)-supported rectangular √(7 ) ×√3 phases of In is investigated within the density-functional theory and linear-response. For both single-layer and double-layer √(7 ) ×√3 structures, it...

Electronic structure of the thermoelectric materials PbTe and AgPb18SbTe20 from first-principles calculations

2010 ◽  
Vol 25 (6) ◽  
pp. 1030-1036 ◽  
Author(s):  
Pengxian Lu ◽  
Zigang Shen ◽  
Xing Hu
Keyword(s):  
Band Structure ◽  
Thermoelectric Properties ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Partial Density ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Scanning Transmission ◽  
Linearized Augmented Plane Wave

To investigate the effects of substituting Ag and Sb for Pb on the thermoelectric properties of PbTe, the electronic structures of PbTe and AgPb18SbTe20 were calculated by using the linearized augmented plane wave based on the density-functional theory of the first principles. By comparing the differences in the band structure, the partial density of states (PDOS), the scanning transmission microscope, and the electron density difference for PbTe and AgPb18SbTe20, we explained the reason from the aspect of electronic structures why the thermoelectric properties of AgPb18SbTe20 could be improved significantly. Our results suggest that the excellent thermoelectric properties of AgPb18SbTe20 should be attributed in part to the narrowing of its band gap, band structure anisotropy, the much extrema and large DOS near Fermi energy, as well as the large effective mass of electrons. Moreover, the complex bonding behaviors for which the strong bonds and the weak bonds are coexisted, and the electrovalence and covalence of Pb–Te bond are mixed should also play an important role in the enhancement of the thermoelectric properties of the AgPb18SbTe20.

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