scholarly journals Ab initio investigation on oxygen defect clusters in UO2+x

2008 ◽  
Vol 93 (20) ◽  
pp. 201903 ◽  
Author(s):  
Hua Y. Geng ◽  
Ying Chen ◽  
Yasunori Kaneta ◽  
Motoyasu Kinoshita
Keyword(s):  
Ab Initio ◽  
Oxygen Defect ◽  
Defect Clusters

Oxygen trapping in defect clusters in Fe and FeCr alloy by ion channeling and ab-initio study

2020 ◽  
Vol 532 ◽  
pp. 152032 ◽  
Author(s):  
Vairavel Mathayan ◽  
Jaiganesh Gnanasekaran ◽  
Lakshmanan Chelladurai ◽  
Sundaravel Balakrishnan ◽  
Rajaraman Ramalingam ◽  
...  
Keyword(s):  
Ab Initio ◽  
Ab Initio Study ◽  
Defect Clusters ◽  
Ion Channeling ◽  
Fecr Alloy ◽  
Oxygen Trapping

scholarly journals The critical role of hydrogen on the stability of oxy-hydroxyl defect clusters in uranium oxide

2018 ◽  
Vol 6 (24) ◽  
pp. 11362-11369 ◽  
Author(s):  
Joseph M. Flitcroft ◽  
Marco Molinari ◽  
Nicholas A. Brincat ◽  
Nicholas R. Williams ◽  
Mark T. Storr ◽  
...  
Keyword(s):  
Ab Initio ◽  
Electronic Properties ◽  
Uranium Oxide ◽  
Critical Role ◽  
Defect Clusters ◽  
Structural And Electronic Properties ◽  
The Stability ◽  
Considerable Work

Despite considerable work applying ab initio techniques to model the role of defects on mechanical, structural and electronic properties of oxides, there has been little on the role of trapped hydrogen, despite it being virtually always present.

An ab initio study of the oxygen defect formation and oxide ion migration in (Sr1-xPrx)2FeO4±δ

2021 ◽  
Vol 515 ◽  
pp. 230602
Author(s):  
Nicholas A. Szaro ◽  
Salai Cheettu Ammal ◽  
Fanglin Chen ◽  
Andreas Heyden
Keyword(s):  
Ab Initio ◽  
Defect Formation ◽  
Oxygen Defect ◽  
Ab Initio Study ◽  
Ion Migration ◽  
Oxide Ion

Characterization of Oxygen Defect Clusters in UO2+x Using Neutron Scattering and PDF Analysis

2018 ◽  
Vol 57 (12) ◽  
pp. 7064-7076 ◽  
Author(s):  
Yue Ma ◽  
Philippe Garcia ◽  
Jacques Lechelle ◽  
Audrey Miard ◽  
Lionel Desgranges ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Oxygen Defect ◽  
Defect Clusters ◽  
Pdf Analysis

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

Ab initio band theory approach to electron energy loss near edge structures

1988 ◽  
Vol 46 ◽  
pp. 506-507
Author(s):  
Xudong Weng ◽  
O.F. Sankey ◽  
Peter Rez
Keyword(s):  
Ab Initio ◽  
Local Density ◽  
Interpolation Method ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Large Set ◽  
Theory Approach ◽  
Band Theory ◽  
Atomic Orbitals ◽  
Pseudopotential Calculations

Single electron band structure techniques have been applied successfully to the interpretation of the near edge structures of metals and other materials. Among various band theories, the linear combination of atomic orbital (LCAO) method is especially simple and interpretable. The commonly used empirical LCAO method is mainly an interpolation method, where the energies and wave functions of atomic orbitals are adjusted in order to fit experimental or more accurately determined electron states. To achieve better accuracy, the size of calculation has to be expanded, for example, to include excited states and more-distant-neighboring atoms. This tends to sacrifice the simplicity and interpretability of the method.In this paper. we adopt an ab initio scheme which incorporates the conceptual advantage of the LCAO method with the accuracy of ab initio pseudopotential calculations. The so called pscudo-atomic-orbitals (PAO's), computed from a free atom within the local-density approximation and the pseudopotential approximation, are used as the basis of expansion, replacing the usually very large set of plane waves in the conventional pseudopotential method. These PAO's however, do not consist of a rigorously complete set of orthonormal states.

Examination of Extra Electron Diffraction Spots Observed in Deuterium-Irradiated Silicon by Using Parallel Electron Beam Illumination

1990 ◽  
Vol 48 (2) ◽  
pp. 490-491
Author(s):  
Ryuichiro Oshima ◽  
Shoichiro Honda ◽  
Tetsuo Tanabe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Single Crystal ◽  
Mixed Solution ◽  
Parallel Beam ◽  
Defect Clusters ◽  
Float Zone ◽  
Transmission Electron ◽  
Extra Electron ◽  
Diffraction Patterns

In order to examine the origin of extra diffraction spots and streaks observed in selected area diffraction patterns of deuterium irradiated silicon, systematic diffraction experiments have been carried out by using parallel beam illumination.Disc specimens 3mm in diameter and 0.5mm thick were prepared from a float zone silicon single crystal(B doped, 7kΩm), and were chemically thinned in a mixed solution of nitric acid and hydrogen fluoride to make a small hole at the center for transmission electron microscopy. The pre-thinned samples were irradiated with deuterium ions at temperatures between 300-673K at 20keV to a dose of 1022ions/m2, and induced lattice defects were examined under a JEOL 200CX electron microscope operated at 160kV.No indication of formation of amorphous was obtained in the present experiments. Figure 1 shows an example of defects induced by irradiation at 300K with a dose of 2xl021ions/m2. A large number of defect clusters are seen in the micrograph.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

Sign in / Sign up

Export Citation Format

Share Document