Simulation of Atomic Structure and Diffusion Characteristics of Point Defects in BCC and FCC Metals

2011 ◽  
Vol 172-174 ◽  
pp. 1222-1227 ◽  
Author(s):  
Irina Valikova ◽  
Andrei V. Nazarov
Keyword(s):  
Point Defect ◽  
Point Defects ◽  
Atomic Structure ◽  
Recent Model ◽  
Diffusion Mobility ◽  
Effect Of Pressure ◽  
Fcc Metals ◽  
Diffusion Characteristics ◽  
Temperature Dependences ◽  
And Diffusion

Our recent model has been used to evaluate the point defect characteristics including those determining the effect of pressure on the concentration of vacancies, di-vacancies, interstitials and their diffusion mobility in set of BCC and FCC metals. Our model has been developed to calculate temperature dependences of mentioned features. In contrast to other studies, the vacancy migration volumes have been found for all the metals studied.

The Role of Carbon and Point Defects in Silicon

1985 ◽  
Vol 59 ◽  
Author(s):  
U. Gösele
Keyword(s):  
Point Defect ◽  
Point Defects ◽  
Carbon Concentration ◽  
Diffusion Mechanism ◽  
Intrinsic Point Defect ◽  
Interstitial Carbon ◽  
Frame Work ◽  
Co Precipitation ◽  
And Diffusion

ABSTRACTAn overview of the behavior of intrinsic point defects in silicon and their interaction with carbon is given for temperatures above about 500° C. The diffusive mechanism of carbon in silicon, which involves silicon self-interstitials, is treated in some detail and compared with the diffusion mechanism of oxygen. The solubility of interstitial carbon is estimated. Co-precipitation of carbon and self-interstitials or oxygen are dealt with in terms of simple volume considerations. It is proposed that the contradicting results on the influence of intrinsic point defect supersaturations on oxygen nucleation and precipitation may possibly be explained in the frame-work of opposite effects depending on the carbon concentration. Finally the influence of carbon on the incorporation and diffusion of gold in silicon is discussed.

scholarly journals EQUILIBRIUM AND DIFFUSION CHARACTERISTICS OF SELF-POINT DEFECTS IN VANADIUM

2012 ◽  
Vol 35 (2) ◽  
pp. 60-80
Author(s):  
V.A. Romanov ◽  
◽  
A.B. Sivak ◽  
P.A. Sivak ◽  
V.M. Chernov ◽  
...  
Keyword(s):  
Point Defects ◽  
Diffusion Characteristics ◽  
And Diffusion

Thermal Expansion, Oxygen Non-Stoichiometry and Diffusion Mobility in some Ferrites-Nickelites

2013 ◽  
Vol 200 ◽  
pp. 86-92 ◽  
Author(s):  
Vladimir Vashook ◽  
Jean Rebello ◽  
J.Y. Chen ◽  
Leonid Vasylechko ◽  
Dmytro Trots ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Thermal Expansion ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Diffusion ◽  
Oxygen Exchange ◽  
Diffusion Mobility ◽  
Diffusion Characteristics ◽  
And Diffusion

Crystal structure,thermal expansion, oxygen non-stoichiometry, electrical conductivity and diffusion characteristics of two analogous LaFe0.7Ni0.3O3‑d and PrFe0.7Ni0.3O3‑d compositions were investigated depending on temperature (201000 °C) and oxygen partial pressure (0.6–21000 Pa). The found oxygen diffusion and oxygen exchange coefficients for the both compositions at similar conditions are near to each other and varied in the range of 110‑7110‑5 cm2s‑1 and 510‑6110‑4 cms‑1, respectively.

Point Defects and Diffusion in Nonstoichiometric Metal Oxides

MRS Bulletin ◽  
1991 ◽  
Vol 16 (12) ◽  
pp. 27-32 ◽  
Author(s):  
Rüdiger Dieckmann
Keyword(s):  
Metal Oxides ◽  
Grain Boundaries ◽  
Point Defect ◽  
Point Defects ◽  
Defect Structure ◽  
Ionic Crystals ◽  
Ion Diffusion ◽  
Crystalline Materials ◽  
And Diffusion ◽  
Point Defect Structure

This article briefly reviews the relationships between point defects and ion diffusion in nonstoichiometric ionic crystals, with special emphasis on cubic oxides. It focuses on crystalline materials with negligibly small concentrations of nonequilibrium defects such as dislocations and grain boundaries. First, the concepts used to analyze the point defect structure and the diffusion of ions in nonstoichiometric crystals will be discussed. Then, specific oxides will be considered as examples. These oxides are manganosite, Mn1−ΔO, and spinels of the type Me3−δO4 with Fe and Mn cations, respectively.

Diffusivity and Diffusion Mechanism of Oxygen in Silicon

1985 ◽  
Vol 59 ◽  
Author(s):  
S.-Tong Lee ◽  
D. Nichols
Keyword(s):  
Mass Spectrometry ◽  
Point Defect ◽  
Point Defects ◽  
Oxygen Diffusion ◽  
Secondary Ion Mass Spectrometry ◽  
Diffusion Mechanism ◽  
Processing Conditions ◽  
Float Zone ◽  
And Diffusion ◽  
Secondary Ion

ABSTRACTThe diffusivities of oxygen in Czochralski Si (CZ-Si) and float-zone Si (FZ-Si) have been measured by using secondary ion mass spectrometry. The diffusivity at 700–1160°C deduced from the outdiffused profiles of oxygen incorporated in CZ-Si shows little or no dependence on processing conditions and can be expressed as D = 0.14 exp(−2.53 eV/kT) cm2/s. Diffusivity at 700–1100°C of oxygen implanted in FZ-Si is insensitive to doses and follows D = 0.13 exp(−2.50 eV/kT) cm2/s, which agrees remarkably well with CZ-Si data. Since large variations in point-defect concentrations existed under the conditions studied, the excellent agreement among the diffusivities leads to the conclusion that point defects in Si have little effect on oxygen diffusion. This demonstrates that oxygen diffuses primarily via an interstitial mechanism in the temperature range studied.

Atomic diffusion mediated by intrinsic point defects in GaAs and AlxGa1−xAs–GaAs superlattices

1991 ◽  
Vol 6 (7) ◽  
pp. 1542-1552 ◽  
Author(s):  
Hidehiko Iguchi
Keyword(s):  
Point Defect ◽  
Point Defects ◽  
Atomic Diffusion ◽  
Self Diffusion ◽  
Related Point ◽  
Diffusion Phenomena ◽  
Growth Method ◽  
Antisite Defects ◽  
And Diffusion ◽  
Growth Methods

Point-defect-mediated atomic diffusion in GaAs and AlxGa1−xAs–GaAs superlattices is examined thermodynamically by focusing on activation enthalpy of diffusion. Through a review of available experimental results of impurity diffusion of Si, Zn, and Be, their diffusion phenomena are discussed by taking the characteristics of column-III-site-related point defect, such as Ga vacancy and arsenic-antisite, into consideration. It is suggested that Zn and Be diffusion should be mediated by As-antisite defects. On the other hand, Si diffusion is mediated by either Ga vacancy or As-antisite, depending on the growth method of materials and diffusion conditions. It is argued that As-antisite should be a mediator of diffusion in As-antisite-rich materials and with using As-rich diffusion source under p-type conditions. Cation self-diffusion or interdiffusion is also discussed in the same manner. Impurity-enhanced layer-disordering phenomena are examined by considering the reduction of defect energy of Ga vacancy and As antisite under n-type and p-type conditions, respectively. Beryllium enhanced and suppressed interdiffusion (cation self-diffusion) in MBE-grown AlxGa1−xAs–GaAs superlattices are interpreted in view of point-defect-mediated cation diffusion on the basis of the Fermi-energy dependence of point defect. In order to explain the phenomena, crystal-growth methods and surface-localized point defects which is responsible for Fermi-level stabilization are taken into consideration.

Simulated Dark-Field Electron Micrographs of Point Defects and Organometallics

1975 ◽  
Vol 33 ◽  
pp. 200-201
Author(s):  
William Krakow
Keyword(s):  
Electron Micrographs ◽  
Point Defects ◽  
Structure Determination ◽  
Atomic Structure ◽  
Image Interpretation ◽  
Dark Field ◽  
Field Electron ◽  
Dark Field Microscopy ◽  
Dark Field Electron

Tilted beam dark-field microscopy has been applied to atomic structure determination in perfect crystals, several synthesized molecules with heavy atcm markers and in the study of displaced atoms in crystals. Interpretation of this information in terms of atom positions and atom correlations is not straightforward. Therefore, calculated dark-field images can be an invaluable aid in image interpretation.

Detection of a point defect in a silicon single crystal by high-resolution TEM

1995 ◽  
Vol 53 ◽  
pp. 466-467
Author(s):  
M. Awaji
Keyword(s):  
High Resolution ◽  
Single Crystal ◽  
Point Defect ◽  
Point Defects ◽  
Noise Level ◽  
Dark Field ◽  
Silicon Single Crystal ◽  
High Resolution Image ◽  
Dark Field Imaging ◽  
Field Imaging

It is necessary to improve the resolution, brightness and signal-to-noise ratio(s/n) for the detection and identification of point defects in crystals. In order to observe point defects, multi-beam dark-field imaging is one of the useful methods. Though this method can improve resolution and brightness compared with dark-field imaging by diffuse scattering, the problem of s/n still exists. In order to improve the exposure time due to the low intensity of the dark-field image and the low resolution, we discuss in this paper the bright-field high-resolution image and the corresponding subtracted image with reference to a changing noise level, and examine the possibility for in-situ observation, identification and detection of the movement of a point defect produced in the early stage of damage process by high energy electron bombardment.The high-resolution image contrast of a silicon single crystal in the [10] orientation containing a triple divacancy cluster is calculated using the Cowley-Moodie dynamical theory and for a changing gaussian noise level. This divacancy model was deduced from experimental results obtained by electron spin resonance. The calculation condition was for the lMeV Berkeley ARM operated at 800KeV.

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