Enthalpy of Formation of Various Phases and Formation Energy of Point Defects in Perovskite-Type NaNbO3by First-Principles Calculation

2004 ◽  
Vol 43 (9B) ◽  
pp. 6793-6798 ◽  
Author(s):  
Akio Shigemi ◽  
Takahiro Wada
Keyword(s):  
Enthalpy Of Formation ◽  
Point Defects ◽  
First Principles ◽  
Formation Energy ◽  
First Principles Calculation ◽  
Perovskite Type

scholarly journals First-Principles Study on Various Point Defects Formed by Hydrogen and Helium Atoms in Tungsten

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Qiang Zhao ◽  
Zheng Zhang ◽  
Yang Li ◽  
Xiaoping Ouyang
Keyword(s):  
Point Defects ◽  
First Principles ◽  
Formation Energy ◽  
Interstitial Site ◽  
First Principles Calculation ◽  
Hydrogen Atoms ◽  
Substitutional Site ◽  
Helium Atoms ◽  
Tetrahedral Interstitial Site ◽  
Formation Energies

The different point defects formed by two hydrogen atoms or two helium atoms in tungsten were investigated through first-principles calculation. The energetically favorable site for a hydrogen atom is tetrahedral interstitial site while substitutional site is the most preferred site for a helium atom. The formation energies of two hydrogen or helium atoms are determined by their positions, and they are not simply 2 times the formation energy of a single hydrogen or helium atom’s defect. After relaxation, two adjacent hydrogen atoms are away from each other while helium atoms are close to each other. The reasons for the interaction between two hydrogen or helium atoms are also discussed.

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.

First-principles Studies of Phase Stability and the Neutral Atomic Vacancies in LiNbO3, NaNbO3 and KNbO3

2005 ◽  
Vol 902 ◽  
Author(s):  
Akio Shigemi ◽  
Takahiro Wada
Keyword(s):  
Enthalpy Of Formation ◽  
Density Functional ◽  
Formation Energy ◽  
Type Structure ◽  
Enthalpies Of Formation ◽  
Functional Formalism ◽  
Reducing Atmosphere ◽  
Perovskite Type Oxide ◽  
Formation Energies ◽  
Perovskite Type

AbstractWe overall evaluated the enthalpies of formation and the formation energies of neutral vacancies in ANbO3 (A = Li, Na, K) using a plane-wave pseudopotential method within a density functional formalism. The LiNbO3 phase with the LiNbO3-type structure was confirmed to have lower enthalpy of formation than that with perovskite- or ilmenite-type structure. The NaNbO3 (R3c) and KNbO3 (Bmm2 and R3m) phases with the lowest symmetry were found to have the lowest enthalpy of formation. The formation energy of a A vacancy was found to be the lowest under an oxidizing atmosphere and that of an O vacancy was found to be the lowest under a reducing atmosphere. The formation energy of a Nb vacancy was the highest under both oxygen-rich and -poor conditions. These results are in agreement with the empirical rule that B site defects in perovskite-type oxide do not exist.

scholarly journals First-Principles Assessment of the Structure and Stability of 15 Intrinsic Point Defects in Zinc-Blende Indium Arsenide

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 48 ◽  
Author(s):  
Qing Peng ◽  
Nanjun Chen ◽  
Danhong Huang ◽  
Eric Heller ◽  
David Cardimona ◽  
...  
Keyword(s):  
Fermi Level ◽  
Charge State ◽  
Indium Arsenide ◽  
Point Defects ◽  
First Principles ◽  
Formation Energy ◽  
Fast Diffusion ◽  
Intrinsic Point Defects ◽  
Zinc Blende ◽  
Tetrahedral Sites

Point defects are inevitable, at least due to thermodynamics, and essential for engineering semiconductors. Herein, we investigate the formation and electronic structures of fifteen different kinds of intrinsic point defects of zinc blende indium arsenide (zb-InAs ) using first-principles calculations. For As-rich environment, substitutional point defects are the primary intrinsic point defects in zb-InAs until the n-type doping region with Fermi level above 0.32 eV is reached, where the dominant intrinsic point defects are changed to In vacancies. For In-rich environment, In tetrahedral interstitial has the lowest formation energy till n-type doped region with Fermi level 0.24 eV where substitutional point defects In A s take over. The dumbbell interstitials prefer < 110 > configurations. For tetrahedral interstitials, In atoms prefer 4-As tetrahedral site for both As-rich and In-rich environments until the Fermi level goes above 0.26 eV in n-type doped region, where In atoms acquire the same formation energy at both tetrahedral sites and the same charge state. This implies a fast diffusion along the t − T − t path among the tetrahedral sites for In atoms. The In vacancies V I n decrease quickly and monotonically with increasing Fermi level and has a q = − 3 e charge state at the same time. The most popular vacancy-type defect is V I n in an As-rich environment, but switches to V A s in an In-rich environment at light p-doped region when Fermi level below 0.2 eV. This study sheds light on the relative stabilities of these intrinsic point defects, their concentrations and possible diffusions, which is expected useful in defect-engineering zb-InAs based semiconductors, as well as the material design for radiation-tolerant electronics.

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.

Mechanical properties and point defects of MC (M=Ti, Zr) from first-principles calculation

2018 ◽  
Vol 747 ◽  
pp. 972-977 ◽  
Author(s):  
Liang Chen ◽  
Qian Wang ◽  
Lei Xiong ◽  
Haoran Gong
Keyword(s):  
Mechanical Properties ◽  
Point Defects ◽  
First Principles ◽  
First Principles Calculation

scholarly journals First-Principles Calculation of Point Defects in Uranium Dioxide

2006 ◽  
Vol 47 (11) ◽  
pp. 2651-2657 ◽  
Author(s):  
Misako Iwasawa ◽  
Ying Chen ◽  
Yasunori Kaneta ◽  
Toshiharu Ohnuma ◽  
Hua-Yun Geng ◽  
...  
Keyword(s):  
Point Defects ◽  
Uranium Dioxide ◽  
First Principles ◽  
First Principles Calculation

Nitrogen-induced magnetism in stannates from first-principles calculations

2016 ◽  
Vol 30 (32) ◽  
pp. 1650236
Author(s):  
Wen-Zhi Xiao ◽  
Bo Meng ◽  
Hai-Qing Xu ◽  
Qiao Chen ◽  
Ling-Ling Wang
Keyword(s):  
Magnetic Properties ◽  
Spin Polarization ◽  
First Principles ◽  
Short Range ◽  
Formation Energy ◽  
Spin Splitting ◽  
Coupling Mechanism ◽  
First Principles Calculations ◽  
Nitrogen Doped ◽  
Perovskite Type

First-principles calculations have been used to comparatively investigate electronic and magnetic properties of nitrogen-doped (N-doped) nonmagnetic semiconductor perovskite-type stannate (MSnO3, M = Ca, Sr, Ba). A total magnetic moment of 1.0 [Formula: see text] induced by N is found in MSnO3 supercell with one N dopant. The spontaneous polarization mainly originates from spin splitting on [Formula: see text] state of N. The medium-sized formation energy shows that the N-doped MSnO3 can be realized experimentally under the metal-rich environments, but the clustering tendency and short-range coupling imply that the stannate matrices are unsuitable for magnetizing by substituting N for O. Our study offers a fresh sight of spontaneous spin polarization in [Formula: see text] magnetism. The FM coupling in N-doped MSnO3 should be attributed to the hole-mediated [Formula: see text]–[Formula: see text] coupling mechanism.

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