scholarly journals Tendencies in ABO3 Perovskite and SrF2, BaF2 and CaF2 Bulk and Surface F-Center Ab Initio Computations at High Symmetry Cubic Structure

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1920
Author(s):  
Roberts I. Eglitis ◽  
Juris Purans ◽  
Anatoli I. Popov ◽  
Ran Jia
Keyword(s):  
Oxygen Vacancy ◽  
High Symmetry ◽  
Defect Level ◽  
Abo3 Perovskite ◽  
Surface Oxygen Vacancy ◽  
F Center ◽  
Bulk Oxygen ◽  
Cubic Structure ◽  
Surface Conduction ◽  
Microscopic Energy

We computed the atomic shift sizes of the closest adjacent atoms adjoining the (001) surface F-center at ABO3 perovskites. They are significantly larger than the atomic shift sizes of the closest adjacent atoms adjoining the bulk F-center. In the ABO3 perovskite matrixes, the electron charge is significantly stronger confined in the interior of the bulk oxygen vacancy than in the interior of the (001) surface oxygen vacancy. The formation energy of the oxygen vacancy on the (001) surface is smaller than in the bulk. This microscopic energy distinction stimulates the oxygen vacancy segregation from the perovskite bulk to their (001) surfaces. The (001) surface F-center created defect level is nearer to the (001) surface conduction band (CB) bottom as the bulk F-center created defect level. On the contrary, the SrF2, BaF2 and CaF2 bulk and surface F-center charge is almost perfectly confined to the interior of the fluorine vacancy. The shift sizes of atoms adjoining the bulk and surface F-centers in SrF2, CaF2 and BaF2 matrixes are microscopic as compared to the case of ABO3 perovskites.

THEORETICAL STUDY OF N2O ADSORPTION AND DECOMPOSITION AT REGULAR AND DEFECT SITES OF MgO (001) SURFACE

2003 ◽  
Vol 02 (01) ◽  
pp. 57-64 ◽  
Author(s):  
YI-JUN XU ◽  
JUN-QIAN LI ◽  
YONG-FAN ZHANG
Keyword(s):  
Oxygen Vacancy ◽  
Density Functional ◽  
Density Functional Method ◽  
Functional Method ◽  
Defect Sites ◽  
Surface Oxygen Vacancy ◽  
F Center ◽  
Catalytic Reactivity ◽  
Vacancy Site ◽  
Mgo Surface

The adsorption of N 2 O at regular and defect sites of MgO (001) surface has been studied systematically using cluster models embedded in a large array of point charges by density functional method. The calculated results show that the MgO (001) surface with oxygen vacancies exhibits high catalytic reactivity toward N 2 O adsorptive-decomposition at variance with the regular MgO surface or the surface with magnesium vacancies. Much elongation of O–N bond of N 2 O after adsorption at oxygen vacancy site with O end of N 2 O down indicates that O–N bond has been broken with concurrent production of N 2, leaving a regular site instead of the original oxygen vacancy site (F center). Besides, the MgO (001) surface with magnesium vacancies hardly exhibits catalytic reactivity. It can be concluded that N 2 O dissociation is likely occurred at MgO (001) surface oxygen vacancy sites, which is consistent with the generally accepted viewpoint in the experiment.

F-CENTER IMPACT ON PHOTOELECTROCHEMICAL PROPERTIES IN HEMATITE

2010 ◽  
Vol 24 (18) ◽  
pp. 1963-1970 ◽  
Author(s):  
ARVIDS STASHANS ◽  
RICHARD RIVERA
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Oxygen Vacancy ◽  
Quantum Chemical ◽  
Vacancy Defect ◽  
Chemical Model ◽  
Photoelectrochemical Properties ◽  
Structural And Optical Properties ◽  
F Center ◽  
Quantum Chemical Model

Structural and optical properties of F-center (two electrons trapped by an oxygen vacancy) defect in hematite have been studied using a quantum-chemical model. Calculated absorption energies, 0.9 eV and 3.6 eV, are discussed in terms of the available experimental data. An explanation for the origin of experimentally observed electron depletion in hematite is proposed.

Facile Removal of Bulk Oxygen Vacancy Defects in Metal Oxides Driven by Hydrogen-Dopant Evaporation

2021 ◽  
pp. 9579-9583
Author(s):  
Min Hu ◽  
Qing Zhu ◽  
Yuan Zhao ◽  
Guozhen Zhang ◽  
Chongwen Zou ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Metal Oxides ◽  
Vacancy Defects ◽  
Bulk Oxygen

Surface oxygen vacancy engineering and physical protection by in-situ carbon coating process of lithium rich layered oxide

2021 ◽  
Vol 515 ◽  
pp. 230623
Author(s):  
Vasu Shanmugam ◽  
Sasikala Natarajan ◽  
Laurel Simon Lobo ◽  
Ankita Mathur ◽  
Moodakare B. Sahana ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Carbon Coating ◽  
Coating Process ◽  
Surface Oxygen ◽  
Physical Protection ◽  
Layered Oxide ◽  
Surface Oxygen Vacancy

scholarly journals Surface Oxygen Vacancy Formation Energy Calculations in 34 Orientations of β-Ga2O3 and θ-Al2O3

2020 ◽  
Vol 124 (19) ◽  
pp. 10509-10522 ◽  
Author(s):  
Yoyo Hinuma ◽  
Takashi Kamachi ◽  
Nobutsugu Hamamoto ◽  
Motoshi Takao ◽  
Takashi Toyao ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Formation Energy ◽  
Vacancy Formation Energy ◽  
Vacancy Formation ◽  
Surface Oxygen ◽  
Energy Calculations ◽  
Surface Oxygen Vacancy ◽  
Oxygen Vacancy Formation
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