First principles study of oxygen vacancies in (Mo + C)-doped anatase TiO2

2015 ◽  
Vol 29 (14) ◽  
pp. 1550072 ◽  
Author(s):  
Jie Cui ◽  
Shuhua Liang ◽  
Xianhui Wang ◽  
Jianmin Zhang
Keyword(s):  
Oxygen Vacancy ◽  
Fermi Level ◽  
Conduction Band ◽  
First Principles ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Anatase Tio2 ◽  
Metallic Behavior ◽  
Structural And Electronic Properties ◽  
Projector Augmented Wave

The structural and electronic properties of neutral oxygen vacancies in ( Mo + C )-doped anatase TiO 2 were investigated using frozen-core projector-augmented wave (PAW) method within GGA +U approximation. Six possible oxygen vacancy sites were considered in the present work. The results show that the octahedral vertex adjacent to Mo and opposite from C is the most stable position for oxygen vacancy based on the results of the formation energy. The Fermi level is located at above the bottom of the conduction band and a typical n-type metallic behavior occurs as a result of the oxygen vacancy appeared in ( Mo + C ) doped TiO 2.

scholarly journals First-Principles Study on the Structural and Electronic Properties of N Atoms Doped-Rutile TiO2of Oxygen Vacancies

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Zhong-Liang Zeng
Keyword(s):  
Oxygen Vacancy ◽  
Fermi Level ◽  
First Principles ◽  
Oxygen Vacancies ◽  
Stable State ◽  
Metal Atoms ◽  
Structural And Electronic Properties ◽  
Type Semiconductor ◽  
N Doping ◽  
Impurity Elements

For the propose of considering the actual situation of electronic neutral, a simulation has been down on the basis of choosing the position of dual N and researching the oxygen vacancy. It is found that the reason why crystal material gets smaller is due to the emergence of impurity levels. By introducing the oxygen vacancy to the structure, the results show that while the oxygen vacancy is near the two nitrogen atoms which have a back to back position, its energy gets the lowest level and its structure gets the most stable state. From its energy band structure and density, the author finds that the impurity elements do not affect the migration of Fermi level while the oxygen vacancy has been increased. Instead of that, the conduction band of metal atoms moves to the Fermi level and then forms the N-type semiconductor material, but the photocatalytic activity is not as good as the dual N-doping state.

Formation of oxygen vacancies in Li2FeSiO4: first-principles calculations

2021 ◽  
Vol 23 (36) ◽  
pp. 20444-20452
Author(s):  
Lihong Zhang ◽  
Shunqing Wu ◽  
Jianwei Shuai ◽  
Zhufeng Hou ◽  
Zizhong Zhu
Keyword(s):  
Oxygen Vacancy ◽  
First Principles ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Vacancy Formation Energy ◽  
Vacancy Formation ◽  
First Principles Calculations ◽  
Temperature And Pressure

The oxygen vacancy (left panel) and the vacancy formation energy as a function of temperature and pressure (right panel).

scholarly journals Roles of Oxygen Vacancies in NiMoO4: A First-Principles Study

2021 ◽  
Vol 9 ◽  
Author(s):  
Yuanbing Wen ◽  
Pengcheng Wang ◽  
Xinying Ding ◽  
Xiaobo Feng ◽  
Chen Qing
Keyword(s):  
Oxygen Vacancy ◽  
Band Structure ◽  
First Principles ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
First Principles Calculation ◽  
Density Of State ◽  
Direct Band Gap ◽  
Direct Band ◽  
Conductive Property

Oxygen vacancy has been suggested to play a role in the electrochemical ability of NiMoO4. The band structure and density of state of NiMoO4 bulks with different concentrations of oxygen vacancy were investigated by the first-principles calculation. Original NiMoO4 shows semiconductive properties with a direct band gap of 0.136 eV. When one to three oxygen vacancies were introduced in the NiMoO4 supercell, the band structure of NiMoO4 transforms to metallic properties, and oxygen vacancies formation energy increases with the increased number of oxygen vacancies. The oxygen vacancies in NiMoO4 lead to the increased electron localization of Ni 3d and Mo 3d state nearby the Fermi level, resulting in higher concentration of carriers in NiMoO4 and thus increase in its electrical conductivity. The results demonstrate that introducing oxygen vacancies can improve the conductive property of NiMoO4.

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.

Structural and Electronic Properties of Oxygen Vacancies in Monoclinic HfO2

2007 ◽  
Vol 996 ◽  
Author(s):  
Peter Broqvist ◽  
Alfredo Pasquarello
Keyword(s):  
Oxygen Vacancy ◽  
Optical Absorption ◽  
Total Energy ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Structural And Electronic Properties ◽  
Defect Levels ◽  
Hybrid Density Functional

AbstractWe study structural and electronic properties of the oxygen vacancy in monoclinic HfO2 for five different charge states. We use a hybrid density functional to accurately reproduce the experimental band gap. To compare with measured defect levels, we determine total-energy differences appropriate to the considered experiments. Our results show that the oxygen vacancy can consistently account for the defect levels observed in optical absorption, direct electron injection, and trap-assisted conduction experiments.

THE EFFECT OF HIGH N-DOPED ANATASE TiO2 ON THE BAND GAP NARROWING AND REDSHIFT BY FIRST-PRINCIPLES

2012 ◽  
Vol 26 (27) ◽  
pp. 1250179 ◽  
Author(s):  
QINGYU HOU ◽  
YONGJUN JIN ◽  
CHUN YING ◽  
ERJUN ZHAO ◽  
YUE ZHANG ◽  
...  
Keyword(s):  
Band Gap ◽  
First Principles ◽  
Formation Energy ◽  
Doping Concentration ◽  
Covalent Bond ◽  
Anatase Tio2 ◽  
Structure Population ◽  
Densities Of States ◽  
N Doping ◽  
Band Gap Narrowing

Anatase TiO 2 supercells were studied by first-principles, in which one was undoped and another three were high N -doping. Partial densities of states, band structure, population and absorption spectrum were calculated. The calculated results indicated that in the condition of TiO 2-x N x (x = 0.0625, 0.125, 0.25), the higher the doping concentration is, the shorter will be the lattice parameters parallel to the direction of c-axis. The strength of covalent bond significantly varied. The formation energy increases at first, and then decreases. The doping models become less stable as N -doping concentration increases. Meanwhile, the narrower the band gap is, the more significant will be the redshift, which is in agreement with the experimental results.

scholarly journals HfS2 and TiS2 Monolayers with Adsorbed C, N, P Atoms: A First Principles Study

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 94
Author(s):  
Mailing Berwanger ◽  
Rajeev Ahuja ◽  
Paulo Cesar Piquini
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Molecular Species ◽  
First Principles ◽  
Density Functional ◽  
2D Materials ◽  
Metallic Behavior ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Localized Levels

First principles density functional theory was used to study the energetic, structural, and electronic properties of HfS 2 and TiS 2 materials in their bulk, pristine monolayer, as well as in the monolayer structure with the adsorbed C, N, and P atoms. It is shown that the HfS 2 monolayer remains a semiconductor while TiS 2 changes from semiconductor to metallic behavior after the atomic adsorption. The interaction with the external atoms introduces localized levels inside the band gap of the pristine monolayers, significantly altering their electronic properties, with important consequences on the practical use of these materials in real devices. These results emphasize the importance of considering the interaction of these 2D materials with common external atomic or molecular species.

First-principles exploration of oxygen vacancy impact on electronic and optical properties of ABO3−δ (A = La, Sr; B = Cr, Mn) perovskites

2020 ◽  
Vol 22 (46) ◽  
pp. 27163-27172
Author(s):  
Jongwoo Park ◽  
Yu-Ning Wu ◽  
Wissam A. Saidi ◽  
Benjamin Chorpening ◽  
Yuhua Duan
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Oxygen Vacancy ◽  
First Principles ◽  
Oxygen Vacancies ◽  
Gas Sensing ◽  
Optical Responses ◽  
Sensing Applications ◽  
Optical Gas Sensing ◽  
The Impact

We explore via first-principles the impact of oxygen vacancies on the electronic structure and optical responses of ABO3−δ (A = La, Sr; B = Cr, Mn) perovskites, which provides a reference for optical gas sensing applications.

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