摘要:

Radiation damage associated with grown-in dislocations in crystals which have been irradiated with neutrons between 200 and 400°C is described. It is proposed that point defects precipitate near climbing grown-in dislocations because the capacity of these dislocations to absorb point defects is limited by the rate at which jogs can be nucleated. This limitation is likely to be important only in the early stages of damage formation when the total line length of dislocation in the crystal is low.

ISSN:0033-7579    

DOI:10.1080/00337577808238800

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Thin silver films (700–1000 Å thick) were bombarded by He+ions (energy-7–10 keV, current density-0.1 μA/cm2) at the temperature range 288–725 K. During the bombardment an increase of a specific film resistance was measured. With the help of transmission electron microscopy a formation of helium bubbles in the films with embedded helium particles was observed. By means of a total evaporation of films in high vacuum the implantation coefficient was determined.

ISSN:0033-7579    

DOI:10.1080/00337577808238801

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Thermal annealing properties of silicon samples implanted at room temperature with P ions have been investigated both in the dark and under high energy electron irradiation and uv excitation at temperatures of 440 and 480°C. A significant increase of electrical activity under ionizing conditions has been observed compared to thermal annealing performed in the dark. The resistivity changes during annealing with ionizing radiation behave in a similar way to the ones in the dark with the exception of larger ion doses. The results obtained suggest that the ionization enhances the annealing of electrically active post-implantation defects compensating the implanted ions.

ISSN:0033-7579    

DOI:10.1080/00337577808238802

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The paper reports on the use of transmission electron microscopy (TEM) for discriminating between the crowdion version of the two-interstitial model and other models of radiation damage. The method is based on the specific prediction of the crowdion model that, as a function of the irradiation temperature, vacancy clusters in heavy-ion-bombarded metals should show an increase in size within a narrow temperature interval around the temperature at which the metastable crowdions undergo thermal conversion into the stable Stage-III interstitial configuration. TEM of vacancy clusters produced by irradiation with 30 kV Cu+ions shows such increases in Ni, Cu, Ag, and Pt, whereas the cluster sizes in Au are independent of the irradiation temperature. These results confirm the crowdion model for Ni, Cu, Ag, and Pt as well as the long-standing prediction that in Au the migration of crowdions is suppressed by thermal conversion. (In contrast to the other fcc metals, in Au the crowdion conversion enthalpyHCCis smaller than the crowdion migration enthalpyHCM.) The estimates ofHCCand of the ranges of collision chains derived from the present data on Ni, Cu, Ag, and Pt are found to be ia good agreement with other experiments.

ISSN:0033-7579    

DOI:10.1080/00337577808238803

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Dehydration and adsorption effects on the parameters of thermally stimulated exoemission (TSE) from ceramic samples of BeO are investigated. Adsorption of active gases increase the emissivity of BeO if it is dehydrated by thermovacuum treatment. For the original hydrated sample the adsorption results in a small decrease of TSE intensity. For recombination proceeding in the mobile surface layer it is necessary that it should have some optimum concentration of adsorbed particles. It is an explanation for the data obtained.

ISSN:0033-7579    

DOI:10.1080/00337577808238804

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Experiments have been conducted to study (a) the development and annealing properties of the latent damage trails produced by radon/thoron alpha particles in plastic Solid State Nuclear Track Detectors (SSNTDs), and (b) the diffusion properties of radon and thoron in various media by using SSNTDs. The information thus obtained has been employed for (a) the optimization of the conditions for the construction of radon/thoron dosimeters for uranium/thorium mines, and (b) the use of SSNTDs for prospection and estimation of uranium and thorium. The results indicate that these gases can diffuse even through rocks, and cellulose nitrate detectors, LR-115 and CA80–15, can be profitably employed in dosimetry, prospection, and for the discrimination between uranium and thorium deposits.

ISSN:0033-7579    

DOI:10.1080/00337577808238805

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Stage II damage rates of lead films have been measured after irradiation with 25 MeV oxygen ions at 7.2 K. The thickness of the samples of 3 μm is smaller than the projected range of 11 μm. The damage rates decreased by three orders of magnitude due to increasing Frenkel pair concentration. A model proposed by Lück and Sizmann fits the experimental data reasonably well over a wide range of defect concentration. It is shown that for defect concentrationsc> 10−4spontaneous recombination processes play a major role in the defect production, whereas free migration of defects is of less importance. The extrapolation of the damage rate to zero seems questionable due to the lack of an appropriate damage rate formula for high defect densities. The annealing behaviour of the irradiated lead samples is compared to that found after irradiation with electrons, deuterons, and neutrons.

ISSN:0033-7579    

DOI:10.1080/00337577808238806

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The temperature dependence of the irradiation-induced displacement of As and Sb atoms into ⟨100⟩ channels in diffused crystals of Si-0.1% As, Si-0.4% As and Si-0.1% Sb has been studied by backscattering of 1–2 MeV He+ions. The maximum displaced fraction and the initial displacement rate varied with irradiation temperature, reaching a maximum at approximately 420 K for the Si-0.1% As crystal. The displaced fractions of As and Sb atoms were reduced by irradiation at 30 K after initial irradiation at 293 K. The results indicate that the solute atom displacement was caused by the trapping of several vacancies at each solute atom.

ISSN:0033-7579    

DOI:10.1080/00337577808238807

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A quantum theory of heavy-particle channeling is used to make predictions of channeling effects for a realistic model of a vibrating crystal. The quantum theory requires the total wave function for a screened-Coulomb potential, which is developed using an eikonal method. The shapes of predicted back-scattering dips are shown to depend on two-body effects due to blocking of Fresnel diffraction peaks, and thus to depend sensitively on spatial correlations between the vibrating lattice atoms; corresponding classical calculations contain no analogous effect. Using a Debye model, calculations are compared with data on back scattering of 300 keV protons in silicon, with limited success. Proposals are made for similar experiments in which the effects of correlations should be considerably enhanced.

ISSN:0033-7579    

DOI:10.1080/00337577808238808

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

From Mössbauer measurements onAl57Co samples irradiated above stage I with 2.8 MeV electrons it is found that the temperature dependence of the Debye-Waller factor of57Co impurities having trapped interstitials becomes weaker with increasing number of interstitials trapped at a57Co atom. This behaviour is explained by a linear superposition of two phenomena: The dynamics of57Co impurities with only one trapped interstitial (mixed dumbbell) is determined by jumps in an octahedral cage. When two or more interstitials are trapped, the cage jumps are suppressed and the mixed dumbbells can only perform low frequency vibrations.

ISSN:0033-7579    

DOI:10.1080/00337577808238809

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor