Correlation between the atomic structure, formation energies, and optical absorption of neutral oxygen vacancies in amorphous silica

2005 ◽  
Vol 71 (23) ◽  
Author(s):  
Sanghamitra Mukhopadhyay ◽  
Peter V. Sushko ◽  
A. Marshall Stoneham ◽  
Alexander L. Shluger
Keyword(s):  
Optical Absorption ◽  
Structure Formation ◽  
Amorphous Silica ◽  
Atomic Structure ◽  
Oxygen Vacancies ◽  
Formation Energies

Enhanced negative thermal expansion and optical absorption of In 0.6 (HfMg) 0.7 Mo 3 O 12 with oxygen vacancies

2017 ◽  
Vol 381 (27) ◽  
pp. 2195-2199 ◽  
Author(s):  
Yongguang Cheng ◽  
Yanchao Mao ◽  
Baohe Yuan ◽  
Xianghong Ge ◽  
Juan Guo ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Optical Absorption ◽  
Oxygen Vacancies ◽  
Negative Thermal Expansion

Oxygen vacancy migration in CSZ using density functional theory

2008 ◽  
Vol 1122 ◽  
Author(s):  
Byeong-Eon Lee ◽  
Dae-Hee Kim ◽  
Yeong-Cheol Kim
Keyword(s):  
Density Functional Theory ◽  
Oxygen Vacancy ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Nearest Neighbor ◽  
Functional Theory ◽  
The Third ◽  
Vacancy Migration ◽  
Neighbor Site ◽  
Formation Energies

AbstractWe studied oxygen migration in calcia-stabilized cubic zirconia (CSZ) using density functional theory. A Ca atom was substituted for a Zr atom in a 2×2×2 ZrO2 cubic supercell, and an oxygen vacancy was produced to satisfy the charge neutrality condition. We found that the formation energies of an oxygen vacancy, as a function of its location with respect to the Ca atom, were varied. The relative formation energies of the oxygen vacancies located at the first-, second-, third-, and fourth-nearest-neighbors were 0.0, −0.07, 0.19, and 0.19 eV, respectively. Therefore, the oxygen vacancy located at the second-nearest-neighbor site of the Ca atom was the most favorable, the oxygen vacancy located at the first-nearest-neighbor site was the second most favorable, and the oxygen vacancies at the third- and fourth-nearest-neighbor sites were the least favorable. We also calculated the energy barriers for the oxygen vacancy migration between oxygen sites. The energy barriers between the first and the second nearest sites, the second and third nearest sites, and the third and fourth nearest sites were 0.11, 0.46, and 0.23 eV, respectively. Therefore, the oxygen vacancies favored the first- and second-nearest-neighbor oxygen sites when they drifted under an electric field.

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.

Point-defects in magnesium sulfide

1994 ◽  
Vol 9 (1) ◽  
pp. 132-134
Author(s):  
Upendra Puntambekar ◽  
Sunder Veliah ◽  
Ravindra Pandey
Keyword(s):  
Optical Absorption ◽  
Shell Model ◽  
Point Defects ◽  
Formation Energy ◽  
Vacancy Mechanism ◽  
Migration Energy ◽  
Absorption Energy ◽  
Defect Energies ◽  
Formation Energies ◽  
Magnesium Sulfide

The results of a study of point defects in MgS are presented. First we obtain empirical interionic potentials in the framework of a shell model and then calculate defect energies using the HADES and ICECAP simulation procedures. The calculated Schottky formation energy is 10.9 eV in comparison to the cation and anion Frenkel formation energies of 11.9 and 25.1 eV, respectively. The migration energy by the vacancy mechanism of the Mg2+ and S2− ions is predicted to be 2.5 and 3.4 eV, respectively. One-electron ICECAP calculations yield the optical absorption energy of 3.1 eV for the F+ center in MgS.

Atomic Structure of a CeO2Grain Boundary: The Role of Oxygen Vacancies

Nano Letters ◽  
2010 ◽  
Vol 10 (11) ◽  
pp. 4668-4672 ◽  
Author(s):  
Hajime Hojo ◽  
Teruyasu Mizoguchi ◽  
Hiromichi Ohta ◽  
Scott D. Findlay ◽  
Naoya Shibata ◽  
...  
Keyword(s):  
Atomic Structure ◽  
Oxygen Vacancies

Photoluminescence and optical absorption studies of the effects of heat treatment on cuprous oxide

1983 ◽  
Vol 61 (10) ◽  
pp. 1423-1427 ◽  
Author(s):  
C. K. Teh ◽  
F. L. Weichman
Keyword(s):  
Optical Absorption ◽  
Cuprous Oxide ◽  
Oxygen Vacancies ◽  
Short Wave ◽  
Luminescent Intensity ◽  
Low Oxygen ◽  
Reducing Atmosphere ◽  
Absorption Studies ◽  
Different Types ◽  
Absorption Measurements

The defects responsible for the short-wave (720 nm) and medium-wave (820 nm) luminescence in cuprous oxide can be created by annealing the crystal at a temperature of 1050 °C under low oxygen pressures. The annihilation of these defects has been observed from the photoluminescence and optical absorption measurements after the crystal has been subjected to a second annealing in the temperature range of about 750 °C under a reducing atmosphere. From the photoluminescence measurements, the density of these defects is found to decrease exponentially as a function of annealing time, as manifested by the reduction in the luminescent intensity. The rate of reduction in intensity is also found to increase with annealing temperature.Because the defects responsible for the luminescence are ascribed to various forms of oxygen vacancies, we believe the decrease in luminescence is due to a reduction in the oxygen vacancies resulting from the formation of copper precipitates in the crystal. The short-wave and medium-wave emissions, which are ascribed to different types of oxygen vacancies, are found to have different activation energies of diffusion.

Positive and Negative Oxygen Vacancies in Amorphous Silica

2019 ◽  
Vol 19 (2) ◽  
pp. 3-17 ◽  
Author(s):  
Anna Kimmel ◽  
Peter Sushko ◽  
Alexander Shluger ◽  
Gennadi Bersuker
Keyword(s):  
Amorphous Silica ◽  
Oxygen Vacancies
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