摘要:

Earlier studies of the ion bombardment induced ripple morphology on the surfaces of amorphous solids when compared with geomorphological effects are shown to possess many similar features. The present study, with 40 keV Ar+ion bombarded Si suggests that analogies are incomplete, however, and that greater similarities with the process of macroscopic sandblasting (corrasion) exist. It is shown that the genesis of wave like structures on Si is from isolated features, which have the appearance of ripple trains, which are faceted. It is suggested that these features result from particle flux enhancement processes near surface dimples generated by stress induced surface lifting.

ISSN:0033-7579    

DOI:10.1080/00337577708237469

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The SiC synthesis was performed in both natural diamond and silicon as a result of the Si and C ion implantation, respectively, followed by annealing at temperatures in the range from 500° to 1200°C. The ion energy 40 keV and doses 3.7 · 1017and 4.1 · 10 cm−2were used at a dose rate of about 2μA cm−2.

ISSN:0033-7579    

DOI:10.1080/00337577708237470

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Measurements have been made of the least electron energy required to cause visible displacement damage in specimens of iron of various orientations. The results are compared with theoretical predictions of the displacement energy1and earlier experiments.2,3The relevance of such observations to the understanding of the displacement energy surface is critically discussed.

ISSN:0033-7579    

DOI:10.1080/00337577708237471

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Channeling measurements have been utilized to investigate the reordering of amorphous layers produced by implantation of 100 keV Zn or 400 keV Se ions at a dose of 3 × 1013ions/cm2into GaAs substrates at LN2temperatures. Annealing was carried out at temperatures between 200 and 600°C for <100>, <111> and <110> oriented substrates. From the results of annealing experiments we conclude that reordering of amorphous layers is not a simple epitaxial regrowth process as is found for implanted Si and Ge. Analysis with X-ray diffraction and TEM techniques show that the reordered layer is epitaxial on the underlying substrate but appreciable disorder in the form of sub-structure is present.

ISSN:0033-7579    

DOI:10.1080/00337577708237472

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Stopping power measurements have been made for4He,12C,14N,16O,20Ne,28Si, and40Ar ions in gold for energies 50–500 KeV. The first Z1oscillation appears to have a larger amplitude in gold than in carbon for projectile velocitiesV= 0.91V0and 0.63V0.

ISSN:0033-7579    

DOI:10.1080/00337577708237473

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Track registration and retention characteristics of natural quartz and its synthetic counterpart Vitreosil (fused silica) have been studied. Tests have been carried out at high temperatures (200–1000°C) and the detectors subjected to intense γ-ray fields of up to 250 MRads, with a view to establishing their suitability for high temperature in-core neutron fluence measurements. Both the major crystallographic axes of natural quartz reveal registration efficiencies of the order of unity showing little or no anisotropy when etched in boiling 65% NaOH, although superficial etching anisotropy of the track openings is highly evident. Whereas quartz shows residual tracks of fission fragments at ≃950°C, in both the major axes, tracks in vitreosil anneal out at 650°C. Annealing studies of the track ranges have not established preferential annealing relative to either axes, and the measurements of the reaction rates have yielded probable activation energies for annealing of 3.83 eV, and 0.85 eV for quartz and vitreosil respectively. Natural quartz can therefore be used as a neutron monitor in the extreme conditions of temperature and background radiation of the reactor core.

ISSN:0033-7579    

DOI:10.1080/00337577708237474

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Results on optical absorption and thermoluminescence of KF coloured by γ rays are reported in this paper. With optical bleaching, F centre absorption maxima shifted from 455 nm to 475nm. The shift was accompanied by the appearance of additional peaks in glow curves. These changes are attributed to deformational effects.

ISSN:0033-7579    

DOI:10.1080/00337577708237475

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

We have studied solute clustering arising from fission-fragment (FF) irradiation of a Au-Fe alloy (17 at.%) by measuring the magnetic ordering temperature through Mössbauer spectroscopy. Up to about 3 × 10−3displacements per atom (dpa) and a dose rate of about 3 × 10−7dpa/s, the FF-irradiation results are very similar to those obtained by neutron irradiation. At high-dose, high-dose-rate FF irradiations, a large and rather abrupt increase in the magnetic ordering temperature was observed, suggesting a fundamental change in the microstructure of the alloy. This change is apparently submicroscopic, as preliminary electron transmission microscopy showed some coarsening of the grains, but no evidence of segregation. Although requiring further development, fission-fragment damage experiments are very promising as a technique for achieving very high dpa levels in conveniently short times.

ISSN:0033-7579    

DOI:10.1080/00337577708237476

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The effect of carbon on void formation in neutron-irradiated high purity nickel was investigated using transmission electron microscopy. After irradiation to fluences ranging from 4.0 × 1018to 2.0 × 1020n/cm2(E > 0.1 MeV) at 500 and 710°C, voids were found in specimens containing up to 84 wppm carbon, whereas void formation was not observed in specimens with 600 wppm carbon. The present results have thus revealed a pronounced suppressing effect of interstitial carbon atoms on void formation. A quantitative analysis on void size and density indicates that the effect of carbon is mainly on void nucleation, not on void growth. A trapping mechanism, based on a relatively large divacancy-carbon atom complex binding energy of 0.86 eV, is proposed in which the dissolved carbon atoms are assumed to effectively trap at least two vacancies per carbon atom. This trapping mechanism is dynamic in nature because “free” interstitial carbon atoms are quite mobile in the nickel lattice at and above 500°C.

ISSN:0033-7579    

DOI:10.1080/00337577708237477

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337577708237478

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor