Discussion of “self-diffusion coefficients of carbon in Fe3C at 723 K via the kinetics of formation of this compound

A study has been made of the kinetics of the diffusion of anhydrous FeC1, in graphite. I t was found that this process can be represented for stages between 50 and 100 per cent. saturation of the graphite and at temperatures in the range 200 to 360 OC by a relation of the type δc/δt = D(δ2c/δr2 + δc/δ/r), providing the diffusion coefficient D is assigned several values for concentrations of occluded FeCl3 above and below a critical concentration. The value of the latter was found to be about two-thirds the saturation concentration of FeCl3 in graphite, this value apparently being the point at which open hexagonal packing of intercalated ferric ions is complete and a closer hexagonal packing commences. Values of the activation energies of occlusion for concentrations above and below two-thirds saturation were found from the relations of corresponding values of diffusion coefficients to temper- ature. The small difference between these activation energies which were of the order of 2 to 3 kcal is attributed to a cancelling of effects, thus the energy necessary to separate carbon lamellae in early stages of occlusion is offset in later stages by hindrance imposed on diffusing molecules by those already occluded. Reduction of particle size of graphite accelerated the occlusion of FeCl3.

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Molecular Dynamics Study of Mass Transport Properties of Liquid Cu-Ag Alloys

Diffusion Foundations ◽

10.4028/www.scientific.net/df.9.58 ◽

2016 ◽

Vol 9 ◽

pp. 58-72 ◽

Cited By ~ 2

Author(s):

U. Sarder ◽

Alexander V. Evteev ◽

Elena V. Levchenko ◽

A. Kromik ◽

I.V. Belova ◽

...

Keyword(s):

Molecular Dynamics ◽

Mass Transport ◽

Transport Properties ◽

Diffusion Coefficients ◽

Md Simulations ◽

Embedded Atom Method ◽

Self Diffusion ◽

Phenomenological Coefficient ◽

Embedded Atom ◽

Kinetics Of

In this study, mass transport properties of liquid Cu-Ag alloys are investigated over wide temperature and composition ranges. The calculations are performed within the framework of the Green-Kubo (GK) formalism by using equilibrium molecular dynamics (MD) simulations along with one of the most reliable embedded-atom method potentials for this system developed by [P. Williams et al.: Modell. Simul. Mater. Sci. Eng. vol. 14 (2006), p. 817]. The approach employed allows for evaluation of the components’ self-diffusion coefficients as well as the phenomenological coefficient for mass transport Lcc. The results obtained in this study can be used to predict the kinetics of solidification of real liquid Cu-Ag alloys.

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Kinetics and Mechanism of MAg4I5 Formation in the Solid-State Reactions Between β-Agl and MI (M = K, Rb, NH4)

Zeitschrift für Naturforschung A ◽

10.1515/zna-1975-6-731 ◽

1975 ◽

Vol 30 (6-7) ◽

pp. 909-910

Author(s):

Giorgio Flor ◽

Vincenzo Massarotti ◽

Riccardo Riccardi

Keyword(s):

Solid State ◽

Diffusion Coefficients ◽

The Self ◽

Solid State Reactions ◽

Contact Method ◽

Self Diffusion ◽

Rate Determining Step ◽

Kinetics Of ◽

Wagner’S Theory ◽

Counter Diffusion

Abstract The kinetics of MAg4I5 (M=K, Rb, NH4) formation from β-AgI and MI are investigated on pellets by the contact method. For all the three reactions involved, the governing mechanism is found to be the cation counter-diffusion while the rate-determining step is the diffusion of M+ . On the basis of Wagner's theory the self-diffusion coefficients of K+ , Rb+ and NH4+ are evaluated in the three compounds.

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An Explanation of the Influence of the Order-Disorder B2-B.C.C Transformation of the Self-Diffusion Behaviour in Alloys

MRS Proceedings ◽

10.1557/proc-21-319 ◽

1982 ◽

Vol 21 ◽

Author(s):

H. Bakker

Keyword(s):

Diffusion Coefficients ◽

Isotope Effects ◽

Tracer Diffusion ◽

The Self ◽

Disorder Transition ◽

Self Diffusion ◽

Kinetics Of ◽

Diffusion Behaviour

ABSTRACTTheories describing the kinetics of ordered B2 and disordered b.c.c. alloys are applied to the effect of the order-disorder transition on tracer diffusion. Both tracer self-diffusion coefficients and isotope effects in βCuZn and equiatomic FeCo are considered.

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Monitoring Therapeutic Response of Metastatic Breast Lesions Using Magnetic Resonance Imaging of Water Self-Diffusion Coefficients

10.21236/ada421349 ◽

2003 ◽

Author(s):

Douglas J. Ballon

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Diffusion Coefficients ◽

Therapeutic Response ◽

Metastatic Breast ◽

Breast Lesions ◽

Resonance Imaging ◽

Self Diffusion

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Kinetics of cyclization of S-ethoxycarbonylmethylisothiouronium chloride to 2-imino-4-thiazolidone

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19790912 ◽

1979 ◽

Vol 44 (3) ◽

pp. 912-917 ◽

Cited By ~ 1

Author(s):

Vladimír Macháček ◽

Said A. El-bahai ◽

Vojeslav Štěrba

Keyword(s):

Hydrochloric Acid ◽

Dilute Hydrochloric Acid ◽

Base Catalysis ◽

General Base ◽

Rate Limiting Step ◽

Limiting Step ◽

Kinetics Of Formation ◽

Acid Catalyzed ◽

Rate Limiting ◽

Kinetics Of

Kinetics of formation of 2-imino-4-thiazolidone from S-ethoxycarbonylmethylisothiouronium chloride has been studied in aqueous buffers and dilute hydrochloric acid. The reaction is subject to general base catalysis, the β value being 0.65. Its rate limiting step consists in acid-catalyzed splitting off of ethoxide ion from dipolar tetrahedral intermediate. At pH < 2 formation of this intermediate becomes rate-limiting; rate constant of its formation is 2 . 104 s-1.

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Cyclization and acid-catalyzed hydrolysis of O-benzoylbenzamidoximes

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19862786 ◽

1986 ◽

Vol 51 (12) ◽

pp. 2786-2797

Author(s):

František Grambal ◽

Jan Lasovský

Keyword(s):

Reaction Rate ◽

Kinetic Isotope ◽

Acid Base Equilibrium ◽

Mineral Acids ◽

Kinetics Of Formation ◽

Acid Catalyzed ◽

Ph Scale ◽

Kinetics Of ◽

Hydrolysis Of ◽

Derivatives Of

Kinetics of formation of 1,2,4-oxadiazoles from 24 substitution derivatives of O-benzoylbenzamidoxime have been studied in sulphuric acid and aqueous ethanol media. It has been found that this medium requires introduction of the Hammett H0 function instead of the pH scale beginning as low as from 0.1% solutions of mineral acids. Effects of the acid concentration, ionic strength, and temperature on the reaction rate and on the kinetic isotope effect have been followed. From these dependences and from polar effects of substituents it was concluded that along with the cyclization to 1,2,4-oxadiazoles there proceeds hydrolysis to benzamidoxime and benzoic acid. The reaction is thermodynamically controlled by the acid-base equilibrium of the O-benzylated benzamidoximes.

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Self-Diffusion Coefficients in the Mixture Dimethylformamide-Benzene, Conclusions Concerning Association

Zeitschrift für Physikalische Chemie ◽

10.1524/zpch.1981.125.1.061 ◽

1981 ◽

Vol 125 (1) ◽

pp. 61-66 ◽

Cited By ~ 4

Author(s):

M. Holz ◽

H. G. Hertz

Keyword(s):

Diffusion Coefficients ◽

Self Diffusion

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Theoretical Modelling of Ion Exchange Processes in Glass: Advances and Challenges

Applied Sciences ◽

10.3390/app11115070 ◽

2021 ◽

Vol 11 (11) ◽

pp. 5070

Author(s):

Xesús Prieto-Blanco ◽

Carlos Montero-Orille

Keyword(s):

Ion Exchange ◽

Diffusion Coefficients ◽

Molten Salts ◽

Theoretical Modelling ◽

Copper Films ◽

Theoretical Frameworks ◽

Self Diffusion ◽

Exchange Processes ◽

The One ◽

Made In

In the last few years, some advances have been made in the theoretical modelling of ion exchange processes in glass. On the one hand, the equations that describe the evolution of the cation concentration were rewritten in a more rigorous manner. This was made into two theoretical frameworks. In the first one, the self-diffusion coefficients were assumed to be constant, whereas, in the second one, a more realistic cation behaviour was considered by taking into account the so-called mixed ion effect. Along with these equations, the boundary conditions for the usual ion exchange processes from molten salts, silver and copper films and metallic cathodes were accordingly established. On the other hand, the modelling of some ion exchange processes that have attracted a great deal of attention in recent years, including glass poling, electro-diffusion of multivalent metals and the formation/dissolution of silver nanoparticles, has been addressed. In such processes, the usual approximations that are made in ion exchange modelling are not always valid. An overview of the progress made and the remaining challenges in the modelling of these unique processes is provided at the end of this review.

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