摘要:

The relevant factors which must be considered for the empirical fitting of a two-body interatomic interaction to the elastic moduli and phonon dispersion relations are discussed. It is shown that for nickel and copper there is no necessity to use any more complex interaction than a near-neighbor central force. There is, however, no unique way to determine an appropriate potential from perfect lattice data alone, since the interaction must be known at distances which do not occur in the perfect lattice for the calculation of lattice defect properties. A set of three potentials for copper, all of which are equivalent for the perfect lattice, were used to investigate the sensitivity of vacancy and interstitial formation and migration energies to the details of the potential. Vacancy calculations were not very sensitive, the ratio E v/(E +E v) varying from about 0.4 to 0.5. The interstitial results showed an overall greater sensitivity, as the relative formation energy of different defect configurations, including which defect is the most stable, varied with the potential. In all cases, however, the migration energy remained small. Although the detailed results are dependent on variations in the interactions, the overall picture presented by the calculations is unchanged-vacancy migration energies equal to or slightly less than formation energies, large interstitial formation energies, and small interstitial migration energies. Independent of the details of the potential and in agreement with earlier calculations, this work indicates that radiation damage annealing due to free migration of interstitials occurs in the so-called Stage I region.

ISSN:0033-7579    

DOI:10.1080/00337576908235573

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The present study provides data on the effect of total neutron dose and gas concentration on mobility and release of fission gases in UC, a question that is important for the swelling problem. UC powders with a carbon content of 4.68% were irradiated at reactor ambient temperature to doses between 1.5 × 1014and 1.5 × 1019nvt. The release of fission xenon was measured at a constant temperature of 1000C°. With increasing dose, a pronounced decrease with dose in the apparent diffusion coefficient was observed indicating trapping (i.e. gas-damage or gas-gas interactions). The kinetics of the release and the nature of the traps are discussed. The results are confirmed by additional data using UC single crystals that were labeled with xenon to different concentrations using ion bombardment techniques. The combined results yield a consistent picture of fission gas mobility and trapping in UC.

ISSN:0033-7579    

DOI:10.1080/00337576908235574

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Single crystals of silicon have been bombarded in channeling and random directions by 66–70 keV ions of neon and phosphorous. The resulting radiation damage has been studied as a function of dose up to approx. 1016ions/cm2by successively measuring the dip in X-ray yields which occurs when protons are injected into the ⟨110⟩ channel.

ISSN:0033-7579    

DOI:10.1080/00337576908235575

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Structural measurements of neutron and ion damage annealing in Si and Ge are compared and interpreted in terms of the annealing of identified defects. Either or both of two prominent isochronal annealing stages above room temperature in neutron irradiated Si are exhibited by X-ray, electron microscope, infrared, and electrical measurements. It is shown that the same two annealing stages are observed in Rutherford scattering measurements of ion implanted Si. Two similar prominent annealing stages are also observed for structural measurements of neutron and ion irradiated Ge. For both Ge and Si the center temperatures for the two annealing stages are approximately 0.35 and 0.5 times the melting temperature. The annealing kinetics and activation energies for the lower temperature stage in Si are correlated with the kinetics and activation energies obtained by analyzing previously reported results on the effects of the substrate temperature and the ion irradiation rate. From a comparison of the time and temperature dependences of the annealing of electron, neutron, and ion damage in Si, it is concluded that the lower temperature isochronal annealing stage near 200°C and the annealing that governs the dose rate dependence of the crystalline to amorphous transition is a consequence of the annealing of divacancies. Support for this conclusion is given by recent infrared measurements of the annealing of ion produced divacancies in Si. The high temperature stage is shown to be near the temperature observed for the epitaxial growth of Si on Si crystal substrates and is interpreted to be related to the annealing of amorphous Si.

ISSN:0033-7579    

DOI:10.1080/00337576908235576

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Les résultats expérimentaux que nous présentons concernent les mesures du coefficient d'émission électronique secondaire de différentes cibles métalliques monocristallines (Feα et Cu) sous bombardement d'ions de gaz rares He+, Ne+, A+, Kr+, Xe+dans le domaine d'énergie 10–100 keV. L'anisotropie observée lorsqu'on fait varier l'incidence du faisceau d'ions sur la cible est due aux variations de la transparence du réseau cristallin de la cible. L'étude des variations du coefficient d'émission correspondant à une direction cristallographique donnée, en fonction de l'énergie et de la nature des ions incidents nous permet une meilleure compréhension des mécanismes qui sont à l'origine des électrons secondaires.

ISSN:0033-7579    

DOI:10.1080/00337576908235577

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

When ethylene, containing a small amount of gaseous alcohol, was irradiated by gamma rays, the G(- C2H4) had a maximum value at the addition of ethyl, isopropyl or t-butyl alcohol less than 0.03 electron fraction. The total concentration of mixtures was 1.1 × 10−4mole/cc. On the other hand, the appearance potential of negative ions, formed by dissociative-resonance-electron-capture processes of slow-electron impact, was measured by mass spectrometer. The lowest value for ethanol (2.7 eV) was much lower than that for ethylene (7.9 eV). This fact suggests that slow electrons in the system are more or less captured by alcohols added to retard the neutralization of positive ethylene ions. The enhancement of the ethylene consumption by adding alcohols is, therefore, attributed to the ion-molecule reactions, that is, the ionic polymerization of ethylene.

ISSN:0033-7579    

DOI:10.1080/00337576908235578

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

The basic physical principles underlying the technique of recoil implantation are discussed in some detail. The number of recoils as a function of recoil energy passing from an evaporated layer into the substrate is calculated for a particular case; and the final penetration distribution within the substrate is compared with that expected for a direct implantation. The number and distribution of unwanted contaminant impurities which inevitably recoil into the substrate during direct implantation through an oxide layer, is also discussed.

ISSN:0033-7579    

DOI:10.1080/00337576908235579

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

摘要:

Frenkel defect annihilation induced by sub-threshold irradiation was studied by simulating low energetic atomic collisions in the neighbourhood of a Frenkel defect in computer model calculations. The fcc model crystal contained 446 atoms. The interaction between the atoms was described by a pairwise interaction Morse potential.

ISSN:0033-7579    

DOI:10.1080/00337576908235580

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337576908235581

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337576908235582

出版商:Taylor & Francis Group    

年代:1969

数据来源: Taylor