The Effect of Structural Relaxation on the Diffusion of Au in Amorphous Pd80Si20

1992 ◽  
Vol 279 ◽  
Author(s):  
A. V. Wagner ◽  
F. Spaepen
Keyword(s):  
Time Dependence ◽  
Viscous Flow ◽  
Concentration Profile ◽  
Structural Relaxation ◽  
Rutherford Backscattering Spectrometry ◽  
New Method ◽  
Relaxation Model ◽  
Sputter Deposited ◽  
Kinetics Of ◽  
Short Times

ABSTRACTThe diffusivity of Au in sputter-deposited amorphous Pd80Si20 has been measured by Rutherford backscattering spectrometry (RBS) between 275°C and 380°C. A new method based on scaling of the evolution of the variance of the concentration profile was used to analyze the data. The diffusivity was found to be independent of the Au concentration below 3 at.%. Structural relaxation causes a time dependence that is evident at short times. The kinetics of this relaxation can be described by the bimolecular relaxation model used in the analysis of viscous flow.

Viscosity, Structural Relaxation and Defect Annihilation Kinetics of Amorphous Si

1990 ◽  
Vol 205 ◽  
Author(s):  
Ann Witvrouw ◽  
Frans Spaepen
Keyword(s):  
Viscous Flow ◽  
Structural Relaxation ◽  
Activation Enthalpy ◽  
Ion Beam ◽  
Time Characteristic ◽  
Annihilation Process ◽  
Dangling Bonds ◽  
Curvature Measurements ◽  
Amorphous Si ◽  
Kinetics Of

AbstractSubstrate curvature measurements were used to monitor viscous flow in ion beam sputtered amorphous Si for temperatures ranging from 150 to 400 °C. The viscosity increases linearly with time, characteristic of a bimolecular defect annihilation process. This is consistent with the defects governing viscous flow being dangling bonds. The isoconfigurational activation enthalpy for the viscosity is 1.8 ±.3 eV.

Numerical investigation of tunnelling contributions to electron scavenging reactions in liquids at short times

1977 ◽  
Vol 55 (11) ◽  
pp. 2124-2132 ◽  
Author(s):  
P. Robin Butler ◽  
Michael J. Pilling ◽  
Stephen A. Rice ◽  
Timothy J. Stone
Keyword(s):  
Diffusion Equation ◽  
Time Dependence ◽  
Numerical Investigation ◽  
Concentration Profile ◽  
Electron Concentration ◽  
Significant Contribution ◽  
Reaction Parameters ◽  
Sink Term ◽  
Short Time ◽  
Short Times

Fick's second diffusion equation, with an added exponential sink term, is integrated numerically to simulate the decay of electrons at short times in the presence of scavengers. The time dependence of the scavenger concentration profile, the scavenging rate constant, and the electron concentration are illustrated graphically. Using the experimental results of Buxton et al. and Jonah et al. It is shown that the Smoluchowski equation is valid within their experimental time ranges provided the cage encounter distance is replaced by Reff, where Reff can be evaluated explicitly in terms of reaction parameters. It is also shown that tunnelling from relaxed traps may make a significant contribution to ultra-short time electron scavenging.

Diffusion of Au in Amorphous Si Measured by the Artificial Multilayer Technique

1989 ◽  
Vol 163 ◽  
Author(s):  
E. Nygren ◽  
B. Park ◽  
L.M. Goldman ◽  
D.T. Wu ◽  
A.V. Wagner ◽  
...  
Keyword(s):  
Time Dependence ◽  
Rutherford Backscattering Spectrometry ◽  
Activation Enthalpy ◽  
Multilayered Films ◽  
Arrhenius Temperature Dependence ◽  
Higher Temperature ◽  
Amorphous Si ◽  
Sputter Deposited ◽  
Arrhenius Temperature ◽  
Good Agreement

AbstractThe diffusivity of Au in amorphous Si (a-Si) has been determined in the temperature range 200-260°C using and Ar-ion sputter deposited artificial multilayered films of a-Si and a-Si(0.7at%Au) with repeat lengths between 44 and 48 Å. Diffusion on lengths scales of the order of interatomic spacings have been investigated. The Au diffusivity exhibits an Arrhenius temperature dependence with an activation enthalpy of 1.2eV and shows good agreement with extrapolations of higher temperature Au diffusion data obtained by Rutherford backscattering spectrometry (RBS) in ion-implanted, CVD, and sputter deposited a-Si. The measured Au diffusivity also shows a significant time dependence.

ChemInform Abstract: Kinetics of the Catalytic Cracking of Paraffins at Very Short Times on Stream

ChemInform ◽  
2010 ◽  
Vol 25 (16) ◽  
pp. no-no
Author(s):  
A. CORMA ◽  
P. J. MIGUEL ◽  
A. V. ORCHILLES
Keyword(s):  
Catalytic Cracking ◽  
Kinetics Of ◽  
Short Times

scholarly journals FEATURES OF QUANTITATIVE MEASUREMENTS OF THE DYNAMIC MODULE OF ELASTICITY OF BINDERS IN OPTIMIZATION OF PRODUCTION TECHNOLOGY SEROGYPSUM COMPOSITE

2021 ◽  
pp. 86-92
Author(s):  
V.I. Tarasevych ◽  
◽  
Yu.G. Gasan ◽  
V.B. Dolgoshey ◽  
◽  
...  
Keyword(s):  
Time Dependence ◽  
Structure Formation ◽  
Elastic Properties ◽  
Physicochemical Characteristic ◽  
Resonance Method ◽  
Acoustic Resonance ◽  
Mechanical Action ◽  
Bending Vibrations ◽  
Damping Decrement ◽  
Kinetics Of

The paper considers the issues of studying the structure formation of binders during hardening to determine the optimal moments of mechanical action on gypsum concrete specimens, which makes it possible to optimize the technology of their impregnation with sulfur melt. The time dependence of the elastic modulus of a hardening, binder is its important physicochemical characteristic, since it is used to objectively identify the stages of structure formation, to simulate the processes occurring at each of the stages. It is noted that the method of acoustic resonance of bending vibrations, in the case of hardening binders, needs correction with respect to the measurement technique and interpretation of the results obtained. The kinetics of the resonance frequency of a sample consisting of a rigid cell and a dispersion poured into it is a function of the elastic properties of the cell, the dispersion itself, the contact zone of the dispersion with cell and therefore cannot be used for either qualitative or quantitative analysis of the kinetics of hardening. Taking into account the elasticity of cuvette is necessary to obtain reliable information. It has been established that in the presence of shrinkage or significant expansion of the binder, the study of structure formation by the resonance method should be carried out in plastic cuvettes. Regardless of shrinkage, the use of a cuvette requires compulsory consideration of its elastic properties. It is advisable to objectively distinguish the stages of structure formation on the basis of the kinetics of not the dynamic modulus of elasticity itself, but the rate of its change. The time dependence of the logarithmic damping decrement is also an important characteristic of the concrete structure. The studies carried out make it possible to obtain serogypsum composites with the necessary performance characteristics and to manufacture elements of architectural décor, wall fencing products of increased aesthetics, durability and reliability from them.

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