SELF-DIFFUSION IN BODY-CENTERED CUBIC ZIRCONIUM

1961 ◽  
Vol 39 (8) ◽  
pp. 1146-1157 ◽  
Author(s):  
G. Kidson ◽  
J. McGurn
Keyword(s):  
Activation Energy ◽  
Melting Point ◽  
Soviet Union ◽  
Diffusion Process ◽  
Diffusion Coefficients ◽  
Body Centered Cubic ◽  
Exponential Factor ◽  
Considerable Evidence ◽  
Self Diffusion ◽  
The Soviet Union

Self-diffusion coefficients of crystal-bar zirconium have been measured between 1500 °C and 1100 °C, using radioactive Zr95 as a tracer. The results may be represented by[Formula: see text]The pre-exponential factor is about three orders of magnitude smaller than that measured in most close-packed systems and the activation energy about one-half that anticipated from an empirical correlation with the melting point. The results, however, are similar to those of a few other recently studied body-centered cubic (BCC) systems, and agree quantitatively with work in the Soviet Union on zirconium. There is considerable evidence that the diffusion process occurs via vacant lattice sites.

Composition and Pressure Dependence of the Diffusion Coefficients in Binary Liquid Alloys

2010 ◽  
Vol 297-301 ◽  
pp. 1371-1376
Author(s):  
Dezső L. Beke
Keyword(s):  
Activation Energy ◽  
Melting Point ◽  
Pressure Dependence ◽  
Diffusion Coefficients ◽  
The Self ◽  
Interatomic Potentials ◽  
Liquid Alloys ◽  
Diffusion In Solids ◽  
Self Diffusion ◽  
Binary Liquid

There are a number of well-known empirical relations for diffusion in solids. For example the proportionality between the self-diffusion activation energy and melting point or between the entropy of the diffusion and the ratio of activation energy and the melting point (Zener rule) are perhaps the best known ‘rules of thumb’. We have shown earlier in our Laboratory, that these relations are direct consequences of the similarity of interatomic potentials seen by ions in solids. On the basis of this, similar relations were extended for impurity and self diffusion in binary solid alloys. In this paper, results for binary liquid mixtures will be reviewed. First a minimum derivation of the temperature dependence of the self-diffusion coefficient, D, is presented (minimum derivation in the sense that it states only that the reduced (dimensionless) D should be a universal function of the reduced temperature), using the similarity of interatomic potentials and dimensional analysis. Then the extension of this relation for determination of the pressure and composition dependence of the self-diffusion coefficients is described using pressure and composition dependent scaling parameters (melting point, atomic volume and mass). The obtained universal form (valid for binary liquid alloys) is very useful for the estimation of the temperature, composition and pressure dependence of the self-diffusion coefficients. Finally, the relation for the ratio of the impurity and self-diffusion coefficients is derived.

Diffusion of ion-implanted Boron and Silicon in Germanium

2004 ◽  
Vol 809 ◽  
Author(s):  
Suresh Uppal ◽  
A. F. W. Willoughby ◽  
J. M. Bonar ◽  
N. E. B. cowern ◽  
R. J. H. Morris ◽  
...  
Keyword(s):  
Activation Energy ◽  
High Resolution ◽  
Diffusion Coefficients ◽  
Doping Concentration ◽  
Diffusion Mechanism ◽  
Concentration Profiles ◽  
Furnace Annealing ◽  
Temperature Range ◽  
Self Diffusion ◽  
Secondary Ion

ABSTRACTThe diffusion of B and Si in Ge is studied using implantation doping. Concentration profiles after furnace annealing in the temperature range 800–900 °C were obtained using high resolution secondary ion mass spectroscopy (SIMS). Diffusion coefficients are calculated by fitting the annealed profiles. For B, we obtain diRusivity values which are two orders of magnitude slower than previously reported in literature. An activation energy of 4.65(±0.3) eV is calculated for B diffusion in Ge. The results suggest that diffusion mechanism other than vacancy should be considered for B diffusion in Ge. For Si diffusion in Ge, the diffusivity values calculated in the temperature range 750–875 °C are in agreement with previous work. The activation energy of 3.2(±0.3) eV for Si diffusion is closer to that for Ge self-diffusion which suggests that Si diffusion in Ge occurs via the same mechanism as in Ge self-diffusion.

Diffusion in Co-Ni System Studied by Multifoil Technique

2011 ◽  
Vol 312-315 ◽  
pp. 466-471 ◽  
Author(s):  
V.D. Divya ◽  
U. Ramamurty ◽  
Aloke Paul
Keyword(s):  
Activation Energy ◽  
Binary System ◽  
Diffusion Couple ◽  
Diffusion Coefficients ◽  
Impurity Diffusion ◽  
Intrinsic Diffusion ◽  
Exponential Factor ◽  
Temperature Range

Diffusion couple experiments were performed in the Co-Ni binary system for determining inter-, impurity- and intrinsic-diffusion coefficients in the temperature range of 1050 - 1250°C. The activation energy and pre-exponential factor estimated for interdiffusion do not vary significantly with composition. The activation energy calculated for impurity diffusion experiments shows is higher than . Intrinsic diffusion coefficients estimated from the multifoil experiment show that Ni is the fastest diffusing species in this system.

CALCULATIONS OF SELF-DIFFUSION PROCESS AND COEFFICIENT IN ORDERED B2 AlCo

2013 ◽  
Vol 27 (19) ◽  
pp. 1341034
Author(s):  
ZHI-SHENG NONG ◽  
JING-CHUAN ZHU ◽  
YONG CAO ◽  
XIA-WEI YANG ◽  
ZHONG-HONG LAI ◽  
...  
Keyword(s):  
Diffusion Process ◽  
First Principles ◽  
Diffusion Coefficients ◽  
Density Functional ◽  
Nearest Neighbor ◽  
The Self ◽  
First Principles Calculations ◽  
Self Diffusion ◽  
Diffusion Mechanisms ◽  
Semi Empirical

The self-diffusion process in B2 type intermetallic compound AlCo has been investigated by the first-principles calculations within the frame work of density functional theory (DFT). The obtained mono-vacancy formation, migration and activation energies for four self-diffusion mechanisms, the next-nearest-neighbor (NNN) jump, [110] six-jump cycle (6JC), straight [100] 6JC and bent [100] 6JC diffusion show that the NNN jump mechanism of Co vacancy requires the lowest activation energy (Q = 6.835 eV ) in these diffusion mechanisms, which indicates that it is the main way of self-diffusion in AlCo . The electronic structure including the electron density difference on (-1 1 0) plane as well as atomic Mulliken populations were calculated, and the change of bonding behavior during the [110] 6JC process was discussed in detail. Finally, the self-diffusion coefficients of NNN jump and 6JC mechanisms for AlCo were also studied via the first-principles calculations and semi-empirical predictions, which indicates that the self-diffusion coefficients for NNN jump of Co vacancy show the highest value than the others.

Tracer diffusion of Ba and Y in YBa2Cu3Ox

1992 ◽  
Vol 7 (9) ◽  
pp. 2308-2316 ◽  
Author(s):  
Nan Chen ◽  
S.J. Rothman ◽  
J.L. Routbort ◽  
K.C. Goretta
Keyword(s):  
Activation Energy ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Self Diffusion ◽  
Speed Up ◽  
Large Anisotropy

Tracer self-diffusion of Ba and Y and the diffusion of Dy, Ho, and Gd, which substitute for Y, have been measured in polycrystalline YBa2Cu3Ox over temperature and oxygen partial pressure ranges of 850 to 980 °C and 103 to 105 Pa, respectively. The diffusion of Ba is slower than that of oxygen or copper, with a high activation energy of about 890 ± 80 kJ/mole. Large anisotropy has also been observed, with diffusion along the c-axis being more than three orders of magnitude slower than diffusion in randomly oriented polycrystals. Diffusion coefficients of Ba were, within experimental uncertainty, independent of oxygen partial pressure over the range measured. The diffusion coefficients of the Y-site species were nearly identical and an activation energy of about 1.0 MJ/mole was estimated, in agreement with that for high-temperature deformation. Attempts to speed up the kinetics through creation of point defects on the Y site by doping proved to be unsuccessful. These results are compared to cation diffusion in cubic perovskites and simple oxides.

Self-diffusion in Molten Silver Iodide

1971 ◽  
Vol 26 (2) ◽  
pp. 329-330 ◽  
Author(s):  
Dan Andréasson ◽  
Anders Behn ◽  
Carl-Axel Sjöblom
Keyword(s):  
Melting Point ◽  
Einstein Equation ◽  
Diffusion Coefficients ◽  
Silver Iodide ◽  
The Self ◽  
Friction Coefficients ◽  
Self Diffusion

Abstract The self-diffusion coefficients of the cation (D+) and of the anion (D-) have been measured in molten silver iodide be­ tween 580 °C and 620 °C with the porous-frit technique. At 610 °C it is found that D+ = D-=5A × 10-5 cm2 s-1. At the melting point (556 °C) D+ melt (4.4 × 10-5 cm2 s-1) is very close to D+ solid (4.3 × 10-5 cm2 s-1) . The Klemm friction coefficients do not indicate the existence of complex entities. D+ and D- calculated according to the Nernst-Einstein equation agree with observed data within 20%.

Self-Diffusion in Isotopically Controlled Heterostructures of Elemental and Compound Semiconductors

1998 ◽  
Vol 527 ◽  
Author(s):  
H. Bracht ◽  
E. E. Haller ◽  
K. Eberl ◽  
M. Cardona ◽  
R. Clark-Phelps
Keyword(s):  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Secondary Ion Mass Spectrometry ◽  
Activation Enthalpy ◽  
Exponential Factor ◽  
Self Diffusion ◽  
Diffusion Studies ◽  
Exponential Factors ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTWe report self-diffusion studies of silicon between 855 and 1388°C in highly enriched epitaxial 28Si layers. Diffusion profiles of 30Si and 29Si are determined with high resolution secondary ion mass spectrometry (SIMS). The temperature dependence of the Si self-diffusion coefficients is accurately described with an activation enthalpy of 4.76 eV and a pre-exponential factor of 560 cm2s-1. The single activation enthalpy indicates that Si self-interstitials dominate self-diffusion over the whole temperature range investigated. Self- and interdiffusion in buried Al71GaAs/Al69GaAs/71GaAs isotope heterostructures with different Al composition is measured between 800 and 1160°C. Ga self-diffusion in AlGaAs and interdiffusion of Al and Ga at the AlGaAs/GaAs interface show that Ga diffusion decreases with increasing Al composition and that the interdiffusion coefficient depends linearly on Al concentration. Furthermore Al is found to diffuse more rapidly into GaAs than Ga diffuses in GaAs. The temperature dependence of Ga and Al diffusion in GaAs and of Ga diffusion in AlGaAs is described by a single activation enthalpy in the range of 3.6±0.1 eV, but by different pre-exponential factors. Differences found for Ga and Al diffusion in GaAs and for Ga diffusion in AlGaAs with different Al concentrations are discussed.

Computer Simulation of Diffusion of Pb-Bi Eutectic in Liquid Sodium by Molecular Dynamics Method

2002 ◽  
Author(s):  
Yingxia Qi ◽  
Minoru Takahashi
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Process ◽  
Diffusion Coefficients ◽  
The Self ◽  
Molecular Dynamics Method ◽  
Pure Liquid ◽  
Empirical Equations ◽  
Potential Candidate ◽  
Self Diffusion ◽  
Dynamics Method

Lead-bismuth eutectic is a potential candidate for coolant of secondary loops of sodium-cooled fast breeder reactors (FBR). The studies on the diffusion of liquid Pb-Bi in liquid Na are carried out corresponding to the case that liquid Pb-Bi leaks to liquid Na by accident. As the diffusion processes are the results of atomic motions, molecular dynamics method has been used to study the diffusion process. The self-diffusion coefficients of pure liquid Pb and Na, and liquid Pb-Bi are calculated and compared with ones by the empirical equations. The discrepancy between them could be eliminated by changing the densities of the liquids. The diffusion of lead-bismuth in sodium is simulated based on the changed densities under which the self-diffusion coefficients of individual liquid metals are close to those by the empirical equations. The simulation results show that the diffusion process of liquid Pb-Bi in liquid Na is a heat releasing process and the density of ternary liquid Na-Pb-Bi is higher than the average value of the densities of liquid Na and liquid Pb-Bi. It is also found that the diffusion coefficients of liquid Pb-Bi in liquid Na are much higher than their self-diffusion coefficients, indicating that liquid Pb-Bi are easy and quickly to diffuse in liquid Na. However, the diffusion coefficient of liquid Na is decreased due to the existence of liquid Pb-Bi, implying that liquid Na-Pb-Bi have a higher viscosity than that of pure liquid Na.

Grain boundary self-diffusion in Ni: Effect of boundary inclination

2005 ◽  
Vol 20 (5) ◽  
pp. 1146-1153 ◽  
Author(s):  
Mikhail I. Mendelev ◽  
Hao Zhang ◽  
David J. Srolovitz
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Boundary Plane ◽  
The Self ◽  
High Symmetry ◽  
Exponential Factor ◽  
Self Diffusion ◽  
Arrhenius Function ◽  
Self Diffusion Coefficient

We examined the influence of the boundary plane on grain-boundary diffusion in Ni through a series of molecular dynamics simulations. A series of 〈010〉 ∑5 tilt boundaries, including several high symmetry and low symmetry boundary planes, were considered. The self-diffusion coefficient is a strong function of boundary inclination at low temperature but is almost independent of inclination at high temperature. At all temperatures, the self-diffusion coefficients are low when at least one of the two grains has a normal with low Miller indices. The grain boundary self-diffusion coefficient is an Arrhenius function of temperature. The logarithm of the pre-exponential factor in the Arrhenius expression was shown to be nearly proportional to the activation energy for diffusion. The activation energy for self-diffusion in a (103) symmetric tilt boundary is much higher than in boundaries with other inclinations. We discuss the origin of the boundary plane density–diffusion coefficient correlation.

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