ISSN:0033-7579    

DOI:10.1080/00337577808233238

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The recovery spectra of the heavy rare earths Gd, Tb, Dy, Ho, Er and Tm were determined after irradiation with electrons at low temperatures. In the cases of Er and Tm, strong thermal cycling phenomena were observed and attributed to hydrogen atoms changing configurations and interacting with the magnetic structure of the metal. After elimination of these effects in Er and Tm, all the spectra—together with those of the earlier treated Lu—had rather similar form: several close-pair peaks followed by a broad complex substage resembling the stageIDin f.c.c metals and attributed to long-range interstitial migration. A correlation is found between the temperature of the maximum of this substage (normalized to the melting temperature) and thec/a-ratio of the metals.

ISSN:0033-7579    

DOI:10.1080/00337577808233239

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Heavy impurities implanted in metals may occupy different sites. In general a substitutional site is possible, as well as sites associated with defects. The interaction of the impurities with the defects produced during the slowing down process is thought to be the reason for the population of the different sites. The incoming atoms are interacting with the correlated damage—interaction with the own damage cascade—and with the uncorrelated damage. The correlated interaction is responsible for the major part of the landing behaviour of the impurities, only the uncorrelated interaction describes the transitions between different sites. With these ideas the evolution of the site populations may be described by means of a set of differential equations. We have solved the equations for the case where all defects are immobile. In order to do so we have introduced spontaneous trapping volumes around every defect configuration. The solutions of these equations produce the evolution of the site populations as a function of dose, trapping volumes, potential between incoming and target atoms, mean displacement energy and range. The site populations are independent of dose rate.

ISSN:0033-7579    

DOI:10.1080/00337577808233240

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The angular and energy distributions of fast ionized recoils produced under both single-crystalline and polycrystalline copper bombardment by 10–35 keV energy noble gas ions have been investigated. The distributions have been found to be strongly affected by regular arrangement of the target atoms. The obtained results are discussed in terms of the simple models of the process.

ISSN:0033-7579    

DOI:10.1080/00337577808233241

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Thermal instabilities due to the recombination of the Frenkel defects have been theoretically studied. The release of the energy stored in the Frenkel pairs leads to a temperature increase which, in its turn, accelerates the process of thermally activated recombination. For sufficiently small heat conductivity and heat transfer to the cryostat this “feed-back” process can lead to a jump-like temperature increase. The criteria for the occurrence of such thermal instabilities have been obtained for the case of the annealing the sample after irradiation and for the case of high defect production rate during irradiation. The criteria depend essentially on the value of the activation energy,W, for the process of recombination; sample size, a; heat transfer coefficient,h;and the concentration of the recombining Frenkel defects,f.

ISSN:0033-7579    

DOI:10.1080/00337577808233242

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Ion-implantation range distributions in inhomogeneous media are calculated with angular deflections included in theP1approximation. The calculations assume power cross sections and neglect electronic stopping. The natural length scale found earlier in the path-length approximation is shown to be general. Attention is concentrated on a two-medium target, but the method may be generalized in an obvious manner to any number of layers of different target media. Results are more explicit when the source and the interface coincide, and are examined in greater detail when the medium behind the coincident source and interface is the vacuum. In this case the mean range within a semi-infinite medium and the reflection coefficient are calculated. The results are expected to be valid for slow light ions on a heavy-atom target. The reflection coefficient is in good agreement with earlier calculations when the target-atom/projectile mass ratio is large.

ISSN:0033-7579    

DOI:10.1080/00337577808233243

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Power-law range, damage, and ionization distributions are calculated analytically in the path-length approximation for the equal-mass case. An analytic expression is given for the asymptotic (large-depth) behaviour of the distributions, and the form of the small-depth behaviour is given. Also, the entire distribution is calculated as an inverse Mellin transform, both by numerical integration and by a numerical application of the stationary-phase method. The asymptotic expression is useful only in the extreme tail of the distribution, the numerical integration is generally valid, and the numerical stationary-phase method is useful except at very small depths. Results are shown for the power parameterm= 0.055, 0.311 and 0.48.

ISSN:0033-7579    

DOI:10.1080/00337577808233244

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Nous avons mesuré une énergie seuil de déplacement moyenne dans le bismuth á 20 K. Elle est de (13 ± 2) eV. La résistivité de 1% de paire de Frenkel a été trouvée égale á 7500 ± 2000 μΩcm, ce qui est très élevé si on compare cette valeur à ceiles mesurées dans les métaux ou données par la règle de Lucasson et Walker.

ISSN:0033-7579    

DOI:10.1080/00337577808233245

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A fully dynamic rate theory for modeling the behavior of point defects in metals during time dependent irradiations has been formulated. The state variable approach has been used to determine the microstructure and defect concentrations as a function of time. The resulting system of stiff non-linear first order ordinary differential equations is solved by the GEAR Program and incorporated into a FORTRAN Computer Code, TRANSWELL. This code has been developed to solve the previous system of equations under a variety of irradiation conditions. It is shown that the point defect and microstructural behavior during the transient phase of an irradiation is quite different than that found after steady state operation.

ISSN:0033-7579    

DOI:10.1080/00337577808233246

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Experimental results obtained by exposure of commercial optical fibers to CO66γ-ray irradiation, are reported. The possibility of utilizing these fibers as far as a total dose of 6000 rad in the light spectrum is shown. It is also shown that it is possible to obtain total recovery of irradiated fibers by annealing at 500°C

ISSN:0033-7579    

DOI:10.1080/00337577808233247

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor