Zinc Diffusion Rates and Profiles in AlGaAs Alloys

1991 ◽  
Vol 240 ◽  
Author(s):  
F. T. J. Smith
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Zinc Concentration ◽  
Diffusion Rate ◽  
Strong Dependence ◽  
Concentration Profiles ◽  
Diffusion Front ◽  
Activation Energy For Diffusion ◽  
Zinc Diffusion ◽  
Diffusion Rates

ABSTRACTThe diffusion rate of Zn in AlxGa1−xAs alloys has been determined, for values of x up to 1.0, as a function of temperature. At 625°C the diffusion coefficient shows a strong dependence on x, reaching a maximum at about 65% Al. A similar rapid increase in diffusion coefficient with x is seen at 700°C. The zinc concentration profiles are similar for all values of x, showing a very abrupt diffusion front. The activation energy for diffusion decreases with increasing x.

Investigation of interdiffusion in (SimGen)p superlattices and Gen buried layers by Raman and X-ray techniques

1992 ◽  
Vol 70 (10-11) ◽  
pp. 852-859 ◽  
Author(s):  
D. J. Lockwood ◽  
J.-M. Baribeau ◽  
H. J. Labbé
Keyword(s):  
Diffusion Coefficient ◽  
Molecular Beam ◽  
Diffusion Rate ◽  
Effective Diffusion ◽  
Atomic Diffusion ◽  
X Ray ◽  
Diffusion Rates ◽  
Buried Layers ◽  
Interface Mixing ◽  
Anneal Temperature

Two thin pseudomorphic (SimGen)p superlattices with m = n = 4 and p = 5 and vice versa were prepared at 350 °C by molecular beam epitaxy on (100) Si to investigate interdiffusion upon annealing. A Raman scattering and X-ray reflectometry study of the as-grown specimens indicated significant interdiffusion at the Si–Ge interfaces. The Raman investigations of specimens annealed for 20 s at temperatures up to 750 °C showed that atomic diffusion across the Si–Ge interfaces had occurred at an anneal temperature of 600 °C. After a 20 s 700 °C anneal. Raman and X-ray techniques showed that the superlattices modulation was destroyed consistent with a diffusion coefficient of about 10−21 m2/s. Both techniques revealed that 100 s anneals at temperatures of 750–950 °C introduced a slower diffusion rate (10−20 m2/s at 950 °C), but also strain relief, in Gen (n < 12) epilayers buried in Si. The differences in the effective diffusion rates for the two types of heterostructure are attributed to a different degree of interface mixing during growth.

Mobility of Ag Atoms in the Binary System Ag2Se-Ag2S: A Molecular Dynamics Study

1997 ◽  
Vol 481 ◽  
Author(s):  
A. Smith ◽  
R. Ravelo ◽  
N. Pingitore
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Binary System ◽  
Arrhenius Plot ◽  
Diffusion Mechanism ◽  
Experimental Measurements ◽  
End Points ◽  
Activation Energy For Diffusion

ABSTRACTThe compounds in the binary system Ag2Se-Ag2S are known to undergo a phase transition to a superionic phase at a temperature which varies with concentration. The diffusion mechanism of Ag ions have been studied in a Molecular Dynamics formalism. We have calculated the diffusion coefficient as function of temperature and concentration and have calculated the activation energy for diffusion from the Arrhenius plot of DAg vs temperature. Results obtained for the end points Ag2Se and Ag2S agree with experimental measurements.

Diffusion Rate of Na+ and Cs+ in Hydrous Titanium(iv) Oxide

1994 ◽  
Vol 353 ◽  
Author(s):  
Fuminori Kasuga ◽  
Hiromichi Yamazaki ◽  
Yasushi Inoue
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficients ◽  
Diffusion Rate ◽  
Activation Energies ◽  
Acid Base ◽  
Base Property ◽  
The Matrix ◽  
Diffusion Rates ◽  
The Difference ◽  
Acid Base Property

AbstractThe diffusion rates of Na+ and Cs+ in two types of hydrous titanium(IV) oxide, precipitated at pH 6 (exchanger A) and pH 13 (exchanger B), were determined radiochemically. The rate of Cs+ in exchanger A is faster than that of Na+; diffusion coefficients are 4.9xl0-11 and 1.9xl0-11 m2 s-1 for Cs+ and Na+, respectively (pH 12, 5.0 °C). The activation energy for Cs+ diffusion is 21 kJ mol-1 and slightly smaller than that for Na+ diffusion, 29 kJ mol-1. The rates of these ions in exchanger B are much slower than those in exchanger A, and can be explained by assuming the existence of two kinds of independently diffusing ions (fast and slow species) in the exchanger. The diffusion coefficients are of the order of 10-12 and 10-13 m2 s-1 for the fast and the slow species, respectively. The activation energies are 48–60 kJ mol-1 for Na+ diffusion and 32–33 kJ mol-1 for Cs+ diffusion (pH 12). The marked difference in kinetics between two exchangers was interpreted in terms of the difference in the acid-base property and in the microstructure of the matrix.

scholarly journals PENGARUH KONSENTRASI DAN SUHU LARUTAN GULA PADA PROSES DEHIDRASI OSMOTIK BUAH NAGA (Hylocereus sp.)

Pro Food ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 440
Author(s):  
Spetriani Spetriani
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Moisture Content ◽  
Osmotic Dehydration ◽  
Initial Moisture Content ◽  
Moisture Diffusivity ◽  
Solution Temperature ◽  
Dragon Fruit ◽  
Activation Energy For Diffusion ◽  
Osmotic Solution

ABSTRACTOsmotic dehydration is a water removing process that carried out on a object by immersing the object into an hyper-tonic (osmotic) solution. The process is commonly applied on pre-drying of fruit. The purpose of this research is to investigate the effect of concentration and temperature of osmotic solution on moisture content change, total dissolved solids change and to determine of water diffusion coefficient and solid diffusion coefficient during the process of osmotic dehydration of dragon fruit. Factorial design was used with 2 factors, each consisting of 3 levels with 3 replication. The treatment on this research are : solution consentration of 30 °Brix, 50 °Brix, and 70 °Brix and solution temperature of 30 °C, 40 °C, and 50 °C were applied to this research. The osmotic dehydration process lasts for 8 hours. Initial moisture content of dragon fruit used for the research between 511.17-665.97 (% db). Moisture and solid diffusivities were in the range of 2.810 x 10-8 m²/s - 7.003 x 10-8 m²/s and 0.973 x 10-8 m²/s until 4.734 x 10-8 m²/s. The activation energy for diffusion of water to the concentration of 30 °Brix, 50 °Brix, and 70 °Brix respectively is 9.963 kJ/mol, 3.249 kJ/mol, and 5.372 kJ/mol. While the activation energy for diffusion of solids is 24.946 kJ/mol, 8.908 kJ/mol, and 27.343 kJ/mol. Keywords: dragon fruit, moisture diffusivity, osmotic dehydration, solid diffusivity ABSTRAK Dehidrasi osmotik adalah suatu proses pengeluaran air yang dilakukan terhadap suatu bahan dengan cara merendam bahan tersebut ke dalam suatu larutan hipertonik. Proses ini pada umumnya diaplikasikan untuk pra-pengeringan buah-buahan. Tujuan penelitian ini adalah untuk mengkaji pengaruh perlakuan konsentrasi dan suhu terhadap perubahan kadar air, perubahan total padatan terlarut dan untuk menentukan nilai koefisien difusi air dan difusi padatan selama proses dehidrasi osmotik pada buah naga. Digunakan rancangan faktorial dengan 2 faktor yang masing-masing terdiri atas 3 taraf dengan 3 kali ulangan. Perlakuan yang digunakan pada penelitian ini adalah variasi konsentrasi larutan 30 °Brix, 50 °Brix, dan 70 °Brix dan suhu larutan 30 °C, 40 °C, dan 50 °C. Proses dehidrasi osmotik berlangsung selama 8 jam. Kadar air awal buah naga yang digunakan untuk penelitian berkisar antara 511,17-665,97 (%db). Nilai difusivitas air antara 2,810 x 10-8 m²/s – 7,003 x 10-8 m²/s dan difusivitas padatan antara 0,973 x 10-8 m²/s - 4,734 x 10-8 m²/s. Energi aktivasi untuk difusi air untuk konsentrasi 30 °Brix, 50 °Brix, dan 70 °Brix secara berurutan adalah 9,963 kJ/mol, 3,249 kJ/mol, dan 5,372 kJ/mol. Energi aktivasi untuk difusi padatan adalah 24,946 kJ/mol, 8,908 kJ/mol, dan 27,343 kJ/mol. Kata kunci: buah naga, dehidrasi osmotik, difusivitas air, difusivitas padatan

Particle Coarsening of Dispersoids In Rapidly Solidified Ti-5Sn-3Y

1985 ◽  
Vol 58 ◽  
Author(s):  
Y.Z. Lu ◽  
B.C. Giessen ◽  
S.H. Whang
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Rare Earth ◽  
Elevated Temperature ◽  
Growth Kinetics ◽  
Diffusion Rate ◽  
Earth Metal ◽  
Ti Alloys ◽  
Rapidly Solidified ◽  
Determining Factor

ABSTRACTRapidly solidified Ti alloys containing rare earth metal dispersoids, such as La or Er, have excellent resistance to coarsening at elevated temperature (700–900°C). In particular, the coarsening of the dispersoid particles in RSP Ti-5Sn-3Y was studied; these particles were found to be Y5Sn3. The measured growth kinetics were found to be compatible with the modified LSW model; it was concluded from the observed parameters that in this alloy the diffusion rate of Y is the rate determining factor, providing a measurement of the diffusion coefficient of Y in a Ti matrix and yielding its activation energy Q = 272 kJ/mole.

Oxygen diffusion in La2−x Srx CuO4−y

1988 ◽  
Vol 3 (1) ◽  
pp. 116-121 ◽  
Author(s):  
J. L. Routbort ◽  
S. J. Rothman ◽  
B. K. Flandermeyer ◽  
L. J. Nowicki ◽  
J. E. Baker
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Mass Spectrometer ◽  
Oxygen Diffusion ◽  
Oxygen Vacancies ◽  
Vacancy Concentration ◽  
Concentration Profiles ◽  
Secondary Ion

Diffusion of 18O in the superconductor La2−x Srx CuO4−y has been measured as a function of x (0 to 0.20) between 300 and 500°C at an oxygen partial pressure of ≍ 1 atm. Concentration profiles were obtained using a secondary ion mass spectrometer. The diffusion coefficient decreases with increasing Sr additions from 0.1 to 0.2, primarily because of an increase in activation energy. This result, which is contradictory to the expectation that the diffusion coefficient should increase with increasing vacancy concentration caused by the added Sr, can be explained if oxygen vacancies are bound to Sr clusters. Measurements on samples with x = 0 or 0.05 were unsuccessful, probably because of porosity.

scholarly journals Surface Thermodynamics, Viscosity, Activation Energy of N-Methyldiethanolamine Aqueous Solutions Promoted by Tetramethylammonium Arginate

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1337
Author(s):  
Xiangfeng Tian ◽  
Lemeng Wang ◽  
Pan Zhang ◽  
Dong Fu
Keyword(s):  
Activation Energy ◽  
Surface Tension ◽  
Diffusion Coefficient ◽  
Aqueous Solutions ◽  
Quantitative Relationship ◽  
Viscosity Data ◽  
Surface Thermodynamics ◽  
Surface Entropy ◽  
Operation Conditions ◽  
Surface Enthalpy

The surface tension and viscosity values of N-methyldiethanolamine (MDEA) aqueous solutions promoted by tetramethylammonium arginate ([N1111][Arg]) were measured and modeled. The experimental temperatures were 303.2 to 323.2 K. The mass fractions of MDEA (wMDEA) and [N1111][Arg] (w[N1111][Arg]) were 0.300 to 0.500 and 0.025 to 0.075, respectively. The measured surface tension and viscosity values were satisfactorily fitted to thermodynamic models. With the aid of experimentally viscosity data, the activation energy (Ea) and H2S diffusion coefficient (DH2S) of MDEA-[N1111][Arg] aqueous solution were deduced. The surface entropy and surface enthalpy of the solutions were calculated using the fitted model of the surface tension. The quantitative relationship between the calculated values (surface tension, surface entropy, surface enthalpy, viscosity, activation energy, and H2S diffusion coefficient) and the operation conditions (mass fraction and temperature) was demonstrated.

scholarly journals Metamorphism of Air Bubbles in a Snow Crystal

1967 ◽  
Vol 6 (46) ◽  
pp. 561-564
Author(s):  
Norikazu Maeno ◽  
Daisuke Kuroiwa
Keyword(s):  
Activation Energy ◽  
Diffusion Processes ◽  
Atomic Diffusion ◽  
Mechanical Relaxation ◽  
Air Bubbles ◽  
A Value ◽  
Snow Crystal ◽  
Activation Energy For Diffusion ◽  
Snow Crystals ◽  
Natural Snow

RésuméObservations have been made of the modification produced by a temperature gradient in the shape of air bubbles in natural snow crystals, and also of the shrinkage of the bubbles with time. The rate of shrinkage is governed by a constant which is strongly temperature dependent with an activation energy of about 15.1 kcal./mole, a value sufficiently similar to the activation energy for diffusion of tritium, dielectric relaxation and mechanical relaxation to suggest that atomic diffusion processes may be responsible for all of these phenomena.

scholarly journals Unexpected Role of Electronic Coupling between Host Redox Centers in Transport Kinetics of Lithium Ions in Olivine Phosphate Materials

2021 ◽  
Author(s):  
Yu Gao ◽  
Jun Huang ◽  
Yuwen Liu ◽  
Shengli Chen
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Lithium Ion ◽  
Transport Kinetics ◽  
Electronic Coupling ◽  
Lithium Ions ◽  
Kinetics Of ◽  
Olivine Phosphate ◽  
Redox Centers

The discrepancy between the trend in the diffusion coefficient of lithium ion (DLi+) and that in the activation energy of ion hopping signals hidden factors determining ion transport kinetics in...

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