Die Berechnung der Auflockerungsw�rme der Metalle aus Rekristallisationsdaten

Liempt, J. A. M. van

doi:10.1007/bf01337708

Cited by 101 publications

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“…(68) for several pure metals are compared in Table 1 Because the diffusion processes, in general, are related to the absolute melting temperature of the host, [84] the grain boundary energies should also be thus related. (68) for several pure metals are compared in Table 1 Because the diffusion processes, in general, are related to the absolute melting temperature of the host, [84] the grain boundary energies should also be thus related.…”

Section: Interrelationship Among Grain Boundary Lattice Diffusion Amentioning

confidence: 99%

Diffusion in Bulk Solids and Thin Films

Gupta

2005

Diffusion Processes in Advanced Technological Materials

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Section: Interrelationship Among Grain Boundary Lattice Diffusion Amentioning

confidence: 99%

Diffusion in Bulk Solids and Thin Films

Gupta

2005

Diffusion Processes in Advanced Technological Materials

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“…ii. The activation energy EA is proportional to the melting temperature of the host metal TM within an accuracy of ± 20 %: EA = 34 * TM [20] (given in [kcal/Mol]). iii The pre-exponential factor Do should be within the following values: 0.05 < Do < 5 [cm2 s-' ] These three rules are generally accepted for self-diffusion in most of the metallic lattices.…”

Section: The Diffusion Mechanismmentioning

confidence: 99%

The role of diffusion in ISOL targets for the production of radioactive ion beams

Beyer

Hagebø

Novgorodov

et al. 2003

Nuclear Instruments and Methods in Physics Research Section B:

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On line isotope separation techniques (ISOL) for production of ion beams of short-lived radionuclides require fast separation of nuclear reaction products from irradiated target materials followed by a transfer into an ion source. As a first step in this transport chain the release of nuclear reaction products from refractory metals has been studied systematically and will be reviewed. High-energy protons (500 -1000 MeV) produce a large number of radionuclides in irradiated materials via the nuclear reactions spallation, fission and fragmentation. Foils and powders of Re, W, Ta, Hf, Mo, Nb, Zr, Y, Ti and C were irradiated with protons (600 -1000 MeV) at the Dubna synchrocyclotron, the CERN synchrocyclotron and at the CERN PS-booster to produce different nuclear reaction products.The main topic of the paper is the determination of diffusion coefficients of the nuclear reaction products in the target matrix, data evaluation and a systematic interpretation of the data. The influence of the ionic radius of the diffusing species and the lattice type of the host material used as matrix or target on the diffusion will be evaluated from these systematics. Special attention was directed to the release of group I, II and III-elements. Arrhenius plots lead to activation energies of the diffusion process. Results:1. 2.A strong radius determined diffusion behaviour was found: Rare earth elements diffuse as Me3+-species.Within the host elements of one period of the periodic table the diffusion of the DVIB'3. In a given target trace elements of group I and II of a lower period diffuse faster than the corresponding elements of the higher period of the periodic table. 132nd period > DSth period > 136th period (DBe >> DSr > DBa)• The diffusion determined transport rate of nuclear reaction products in solid target materials is often satisfactory, and consequently several refractory metals are suited as targets for fast on-line separation of short lived nuclear reaction products. The delay times measured in on line mode at ISOLDE, however, are significantly shorter. An enhancement of the diffusion under radiation condition is considered, subject for further systematic studies. The results obtained in this systematic study may also be applied in the development of alternative separation technologies in medical radionuclide production.

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“…Let us notice than Braune doesn't refer to Arrhenius (Physicists are not well up on the works of Chemists!). Moreover Braune observed that the ratio Q/T m is practically a constant -at least for solids of the same structure, a correlation generally known as Van Liempt rule, Q = 17 RT m in metals -whose paper dates only of 1935 [9]! A renewal of tentative of modelling the temperature dependence of diffusivity in solids didn't appear before 1949, thanks to C. Wert and C.Zener [10] who were looking at the diffusion of interstitials in BCC metals.…”

Section: Physical Modelsmentioning

confidence: 99%

Some Thoughts and/or Questions about Activation Energy and Pre-Exponential Factor

Philibert

2006

DDF

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The first part of this paper presents a brief historical account of the Arrhenius law, starting from the seminal paper by Arrhenius (1889) up to theoretical developments mainly based on the rate theory. The second part describes the so called compensation rule (Meyer-Neldel rule), a correlation between activation enthalpy and entropy (or between pre-exponential factor and activation energy) , and discusses whether this correlation is trivial or bears some physical meaning.

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Die Berechnung der Auflockerungsw�rme der Metalle aus Rekristallisationsdaten

Cited by 101 publications

References 0 publications

Diffusion in Bulk Solids and Thin Films

Diffusion in Bulk Solids and Thin Films

The role of diffusion in ISOL targets for the production of radioactive ion beams

Some Thoughts and/or Questions about Activation Energy and Pre-Exponential Factor

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