Anisotropic interaction between self-interstitial atoms and 1/2 dislocation loops in tungsten

2021 ◽  
Vol 64 (5) ◽  
Author(s):  
Hao Wang ◽  
Ke Xu ◽  
Dong Wang ◽  
Ning Gao ◽  
Yu-Hao Li ◽  
...  
Keyword(s):  
Dislocation Loops ◽  
Anisotropic Interaction ◽  
Interstitial Atoms

The Influence of the Initial Supersaturation of Si Interstitial Atoms on the Relative Thermal Stability of Dislocation Loops in Silicon

2000 ◽  
Vol 610 ◽  
Author(s):  
F. Cristiano ◽  
B. Colombeau ◽  
B. de Mauduit ◽  
F. Giles ◽  
M. Omri ◽  
...  
Keyword(s):  
Relative Stability ◽  
Thermal Evolution ◽  
Dislocation Loops ◽  
Transmission Electron Microscopy Analysis ◽  
Transmission Electron ◽  
Interstitial Atoms ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Implantation Process ◽  
Formation Energies

AbstractIn this work, we have studied the relative stability of perfect (PDLs) and faulted (FDLs) dislocation loops formed during annealing of preamorphised silicon. In particular, we have investigated the effect of the initial supersaturation of Si interstitial atoms (Si(int)s) created by the implantation process on their thermal evolution. Transmission Electron Microscopy analysis shows that in samples with a low Si interstitial supersaturation, FDLs are the dominant defects while PDLs appear as the most stable defects in highly supersaturated samples. We have calculated the formation energies of both types of dislocation loops and found that, for defects of the same size, FDLs are more energetically stable than PDLs, if their diameter is smaller than 80 nm and viceversa. The application of these calculations to the samples studied in this work indicates that a direct correspondence exists between the formation energy of the two defect families and the number of atoms bound to them. Moreover, we have shown that the relative stability of FDLs and PDLs depends on the initial supersaturation of Si(int)s created during the implantation process.

Relative Stability of Perfect and Faulted Dislocation Loops in Silicon

1999 ◽  
Vol 568 ◽  
Author(s):  
M. Omri ◽  
B. de Mauduit ◽  
A. Claverie
Keyword(s):  
Relative Stability ◽  
Thermal Evolution ◽  
Binding Energies ◽  
Dislocation Loops ◽  
Interstitial Atoms ◽  
Extrinsic Defects

ABSTRACTWe have studied by TEM the thermal evolution of a population of extrinsic defects composed of a mixture of both perfect and faulted dislocation loops (PDL's and FDL's respectively). It is shown that, when isolated from an external sink, the FDL's trap the Si interstitial atoms emitted by PDL's. When a highly recombining surface is located close to the defects, it preferably « pumps » the PDL's. On the contrary, injecting Si(int)'s from the surface helps stabilizing the PDL's while the FDL's grow. These experiments clearly show that FDL's are more stable, i.e. have higher binding energies than PDL's.

Transient Enhanced Diffusion of Dopants in Preamorphised Si Layers

1996 ◽  
Vol 438 ◽  
Author(s):  
A. Claverie ◽  
C. Bonafos ◽  
M. Omri ◽  
B. De Mauduit ◽  
G. Ben Assayag ◽  
...  
Keyword(s):  
Ostwald Ripening ◽  
Dislocation Loops ◽  
Boron Diffusion ◽  
Enhanced Diffusion ◽  
Transient Enhanced Diffusion ◽  
Interstitial Atoms ◽  
Extrinsic Dislocation ◽  
The Mean ◽  
Boron Diffusivity ◽  
Shed Light

AbstractTransient Enhanced Diffusion (TED) of dopants in Si is the consequence of the evolution, upon annealing, of a large supersaturation of Si self-interstitial atoms left after ion bombardment. In the case of amorphizing implants, this supersaturation is located just beneath the c/a interface and evolves through the nucleation and growth of End-Of-Range (EOR) defects.For this reason, we discuss here the relation between TED and EOR defects. Modelling of the behavior of these defects upon annealing allows one to understand why and how they affect dopant diffusion. This is possible through the development of the Ostwald ripening theory applied to extrinsic dislocation loops. This theory is shown to be readily able to quantitatively describe the evolution of the defect population (density, size) upon annealing and gives access to the variations of the mean supersaturation of Si self-interstitial atoms between the loops and responsible for TED. This initial supersaturation is, before annealing, at least 5 decades larger than the equilibrium value and exponentially decays with time upon annealing with activation energies that are the same than the ones observed for TED. It is shown that this time decay is precisely at the origin of the transient enhancement of boron diffusivity through the interstitial component of boron diffusion. Side experiments shed light on the effect of the proximity of a free surface on the thermal behavior of EOR defects and allow us to quantitatively describe the space and time evolutions of boron diffusivity upon annealing of preamorphised Si layers.

Estimation of the Number of Injected Interstitial Atoms during Nitrous Oxidation of Silicon

1999 ◽  
Vol 568 ◽  
Author(s):  
D. Skarlatos ◽  
L.F. Giles ◽  
C. Tsamis ◽  
A. Claverie ◽  
D. Tsoukalas
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperatures ◽  
Dislocation Loops ◽  
Ambient Conditions ◽  
Transmission Electron ◽  
Dry Oxidation ◽  
Interstitial Atoms ◽  
The Difference

ABSTRACTIn this work we use dislocation loops to monitor the interstitial injection during the oxynitridation (oxidation in 100% N2O ambient) of silicon at low temperatures (850–950 °C). The interstitials captured by the loops are measured using Transmission Electron Microscopy. The number of Si atoms released after oxynitridation was calculated from the difference in the total amount of atoms stored in the loops between oxidizing and inert ambient. We obtained that this number is larger compared with the respective under the same dry oxidation (in 100% O2 ambient) conditions.

scholarly journals Evolution of dislocation microstructure in irradiated Zr alloys determined by X-ray peak profile analysis

2021 ◽  
Vol 54 (1) ◽  
pp. 280-286
Author(s):  
István Groma ◽  
Ildikó Szenthe ◽  
Éva Ódor ◽  
Bertalan Jóni ◽  
Gyula Zilahi ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Profile Analysis ◽  
Nondestructive Method ◽  
Nuclear Industry ◽  
Dislocation Loops ◽  
Plastic Properties ◽  
X Ray ◽  
Peak Broadening ◽  
Interstitial Atoms ◽  
Zr Alloys

During neutron irradiation of metals, owing to the enhanced number of vacancies and interstitial atoms, the climb motion of dislocations becomes significant at room temperature, leading to a recrystallization of the material. Moreover, the vacancies and interstitial atoms tend to form prismatic dislocation loops that play a crucial role in the plastic properties of the materials. X-ray peak profile analysis is an efficient nondestructive method to determine the properties of dislocation microstructure. In the first half of this article, the foundation of the asymptotic peak broadening theory and the related restricted-moments peak-evaluation method is summarized. After this, the microstructural parameters obtained by X-ray peak profile analysis are reported for irradiated E110 and E110G Zr alloys used as cladding material in the nuclear industry.

scholarly journals Strain Effects on the Diffusion Properties of Near-Surface Self-Interstitial Atoms and Adatoms in Tungsten

2021 ◽  
Vol 8 ◽  
Author(s):  
Bochuan Sun ◽  
Dimitrios Maroudas ◽  
Brian D. Wirth ◽  
Enrique Martínez
Keyword(s):  
Thermal Stresses ◽  
Large Strain ◽  
Material Surface ◽  
Strain Effect ◽  
Dislocation Loops ◽  
Near Surface ◽  
Plasma Facing Components ◽  
Interstitial Atoms ◽  
Different Strains ◽  
Diffusion Properties

Tungsten (W) is a candidate for the plasma-facing components and divertor in future fusion applications. The material will be subject to a large particle influx (mainly helium and hydrogenic species) that will form bubbles. As bubbles grow, they compress the material, adding to thermal stresses, and eject self-interstitial atoms (SIAs—isolated or in clusters) to release internal pressure. These SIAs diffuse towards the surface in large stress/strain fields and on the surface are thought to act as precursors for nanotendril formation (also known as fuzz) that develops on the material surface modifying its morphology. In this work we analyze the effect of strain on the diffusion properties of both SIAs and adatoms. Relying on atomistic simulations, we compute the average time that a SIA created in the center of a tungsten slab takes to reach a (110) surface for different strains and temperatures. This time relates to the SIA diffusivity and allows to compute the activation energy and dipole tensor including surface effects. We observe a large strain effect that significantly modifies the propensity for SIAs to reach the surface and, hence, to cluster to form dislocation loops in the bulk crystal. Strain also alters the diffusivity of the adatom although to a lesser extent. Finally, we report on the resulting surface roughness evolution and its dependence on strain.

Transient Enhanced Diffusion of Dopants in Preamorphised Si Layers

1996 ◽  
Vol 439 ◽  
Author(s):  
A. Claverie ◽  
C. Bonafos ◽  
M. Omri ◽  
B. De Mauduit ◽  
G. Ben Assayag ◽  
...  
Keyword(s):  
Ostwald Ripening ◽  
Dislocation Loops ◽  
Boron Diffusion ◽  
Enhanced Diffusion ◽  
Transient Enhanced Diffusion ◽  
Interstitial Atoms ◽  
Extrinsic Dislocation ◽  
The Mean ◽  
Boron Diffusivity ◽  
Shed Light

AbstractTransient Enhanced Diffusion (TED) of dopants in Si is the consequence of the evolution, upon annealing, of a large supersaturation of Si self-interstitial atoms left after ion bombardment. In the case of amorphizing implants, this supersaturation is located just beneath the c/a interface and evolves through the nucleation and growth of End-Of-Range (EOR) defects.For this reason, we discuss here the relation between TED and EOR defects. Modelling of the behavior of these defects upon annealing allows one to understand why and how they affect dopant diffusion. This is possible through the development of the Ostwald ripening theory applied to extrinsic dislocation loops. This theory is shown to be readily able to quantitatively describe the evolution of the defect population (density, size) upon annealing and gives access to the variations of the mean supersaturation of Si self-interstitial atoms between the loops and responsible for TED. This initial supersaturation is, before annealing, at least 5 decades larger than the equilibrium value and exponentially decays with time upon annealing with activation energies that are the same than the ones observed for TED. It is shown that this time decay is precisely at the origin of the transient enhancement of boron diffusivity through the interstitial component of boron diffusion. Side experiments shed light on the effect of the proximity of a free surface on the thermal behavior of EOR defects and allow us to quantitatively describe the space and time evolutions of boron diffusivity upon annealing of preamorphised Si layers.

Application of Modified Bloch Waves to Image Analysis of Extended Linear Defects

1974 ◽  
Vol 32 ◽  
pp. 402-403
Author(s):  
S. Nakahara ◽  
D. M. Maher
Keyword(s):  
Image Analysis ◽  
Computational Approach ◽  
Dislocation Loops ◽  
Plane Wave Expansion ◽  
Dynamical Equations ◽  
Bloch Waves ◽  
Linear Defects ◽  
Imperfect Crystal ◽  
Localized Defects ◽  
Defective Crystals

Since Head first demonstrated the advantages of computer displayed theoretical intensities from defective crystals, computer display techniques have become important in image analysis. However the computational methods employed resort largely to numerical integration of the dynamical equations of electron diffraction. As a consequence, the interpretation of the results in terms of the defect displacement field and diffracting variables is difficult to follow in detail. In contrast to this type of computational approach which is based on a plane-wave expansion of the excited waves within the crystal (i.e. Darwin representation ), Wilkens assumed scattering of modified Bloch waves by an imperfect crystal. For localized defects, the wave amplitudes can be described analytically and this formulation has been used successfully to predict the black-white symmetry of images arising from small dislocation loops.

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.

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