Grain-boundary diffusion in nanocrystals with a time-dependent diffusion coefficient

2003 ◽  
Vol 45 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
A. A. Nazarov
Keyword(s):  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Time Dependent

Grain Boundary Diffusion in Co/Cu and Co/Cr Magnetic Thin Films

1993 ◽  
Vol 313 ◽  
Author(s):  
John G. Holl-Pellerin ◽  
S.G.H. Anderson ◽  
P.S. Ho ◽  
K.R. Coffey ◽  
J.K. Howard ◽  
...  
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Photoelectron Spectroscopy ◽  
Boundary Diffusion ◽  
Magnetic Thin Films ◽  
Grain Boundary Diffusion ◽  
X Ray ◽  
Before And After

ABSTRACTX-ray photoelectron spectroscopy (XPS) has been used to investigate grain boundary diffusion of Cu and Cr through 1000 Å thick Co films in the temperature range of 325°C to 400°C. Grain boundary diffusivities were determined by modeling the accumulation of Cu or Cr on Co surfaces as a function of time at fixed annealing temperature. The grain boundary diffusivity of Cu through Co is characterized by a diffusion coefficient, D0gb, of 2 × 104 cm2/sec and an activation energy, Ea,gb, of 2.4 eV. Similarly, Cr grain boundary diffusion through Co thin films occurs with a diffusion coefficient, Do,gb, of 6 × 10-2cm2/sec and an activation energy, Ea,gb of 1.8 eV. The Co film microstructure has been investigated before and after annealing by x-ray diffraction and transmission electron Microscopy. Extensive grain growth and texturing of the film occurred during annealing for Co deposited on a Cu underlayer. In contrast, the microstructure of Co deposited on a Cr underlayer remained relatively unchanged upon annealing. Magnetometer Measurements have shown that increased in-plane coercivity Hc, reduced remanence squareness S, and reduced coercive squareness S* result from grain boundary diffusion of Cu and Cr into the Co films.

Zinc Self-Diffusion in ZnO

2005 ◽  
Vol 237-240 ◽  
pp. 163-168 ◽  
Author(s):  
M.A.N. Nogueira ◽  
Antônio Claret Soares Sabioni ◽  
Wilmar Barbosa Ferraz
Keyword(s):  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Volume Diffusion ◽  
Grain Boundary Diffusion ◽  
Polished Surface ◽  
Self Diffusion ◽  
Zinc Diffusion ◽  
Diffusion Profiles

This work deals with the study of zinc self-diffusion in ZnO polycrystal of high density and of high purity. The diffusion experiments were performed using the 65Zn radioactive isotope as zinc tracer. A thin film of the tracer was deposited on the polished surface of the samples, and then the diffusion annealings were performed from 1006 to 1377oC, in oxygen atmosphere. After the diffusion treatment, the 65Zn diffusion profiles were established by means of the Residual Activity Method. From the zinc diffusion profiles were deduced the volume diffusion coefficient and the product dDgb for the grain-boundary diffusion, where d is the grain-boundary width and Dgb is the grain-boundary diffusion coefficient. The results obtained for the volume diffusion coefficient show good agreement with the most recent results obtained in ZnO single crystals using stable tracer and depth profiling by secondary ion mass spectrometry, while for the grain-boundary diffusion there is no data published by other authors for comparison with our results. The zinc grain-boundary diffusion coefficients are ca. 4 orders of magnitude greater than the volume diffusion coefficients, in the same experimental conditions, which means that grain-boundary is a fast path for zinc diffusion in polycrystalline ZnO.

Pressure, temperature, water content, and oxygen fugacity dependence of the Mg grain-boundary diffusion coefficient in forsterite

2018 ◽  
Vol 103 (9) ◽  
pp. 1354-1361 ◽  
Author(s):  
Hongzhan Fei ◽  
Sanae Koizumi ◽  
Naoya Sakamoto ◽  
Minako Hashiguchi ◽  
Hisayoshi Yurimoto ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Water Content ◽  
Oxygen Fugacity ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Boundary Diffusion Coefficient ◽  
Temperature Water

Boron Diffusion in Polycrystalline Silicon

1986 ◽  
Vol 76 ◽  
Author(s):  
Moustafa Y. Ghannam ◽  
Robert W. Dutton ◽  
Steven W. Novak
Keyword(s):  
Grain Size ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Boundary Diffusion ◽  
Crystalline Silicon ◽  
Unit Area ◽  
Grain Boundary Diffusion ◽  
Boron Diffusion

ABSTRACTThe diffusion of boron in ion implanted LPCVD polycrystalline silicon is shown to be dominated by grain boundary diffusion at low and moderate concentrations. The diffusion coefficient is 2 to 3 orders of magnitude larger than its value in crystalline silicon. In preannealed polysilicon, the boron diffusion coefficient is found to be 30% smaller than in polysilicon annealed after implantation. This reflects the effect of the grain size in the diffusion coefficient since preannealed polysilicon has larger grains and smaller density of grain boundaries per unit area.

About Fe Diffusion in Cu

2012 ◽  
Vol 323-325 ◽  
pp. 171-176 ◽  
Author(s):  
D. Prokoshkina ◽  
A.O. Rodin ◽  
V. Esin
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Temperature Dependence ◽  
Boundary Diffusion ◽  
Bulk Diffusion ◽  
Grain Boundary Diffusion ◽  
Radiotracer Technique ◽  
Exponential Factor ◽  
Temperature Range

The temperature dependence of the bulk diffusion coefficient of Fe in Cu is determined by EDX in the temperature range from 923 to 1273 K, , m2/s. These results are different from that obtained earlier by radiotracer technique: activation energy is less by 30 kJ/mol and pre-exponential factor is 50 times smaller. Deviations from ideality of investigated solutions do not explain the differences; consequently, the thermodynamical factor would not responsible for such an effect. Fast grain boundary diffusion of Fe in Cu was not observed in the temperature range from 823 to 1073 K.

Retardation Effect of Grain Boundary Segregation on Grain Boundary Diffusion

2006 ◽  
Vol 249 ◽  
pp. 167-172 ◽  
Author(s):  
Boris S. Bokstein ◽  
Alexey Rodin ◽  
A.N. Smirnov
Keyword(s):  
Solid Solution ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Boundary Diffusion ◽  
Boundary Segregation ◽  
Solute Concentration ◽  
Grain Boundary Diffusion ◽  
Grain Boundary Segregation ◽  
Retardation Effect ◽  
Ordering Transition

The effect of grain boundary segregation (GBS) on grain boundary diffusion (GBD) is analyzed in frame of the new model. This model supposes the formation of the specific “nuclei” in a grain boundary (GB) solid solution. Their composition is close to that of the nearest phase in grain in equilibrium with solid solution in grain. These GB “nuclei” form after the same solubility as in the bulk is reached. The size of these “nuclei” is close to an atomic size and consequently the new interfaces inside the two-dimensional GB are not formed. As the solute concentration in the bulk increases the solute concentration in GB increases as well, but only due to the increase of the “nuclei” fraction. At the same time the solute concentration in a disordered part of GB solid solution remains constant. The fraction of this part decreases. The retardation effect of GBS on GBD is connected with the ordering transition, the “nuclei” formation. A diffusion coefficient (D) in an ordered part of solid solution is close to the diffusion coefficient in a bulk phase. As a rule, it is less than a diffusion coefficient in a disordered part. The growth of an ordered part of GB solid solution (the fraction of the “nuclei”) leads also to the dependence of D on the solute concentration and to the additional curvature of the diffusion profiles.

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