摘要:

The interaction of He atoms with defects in ‘“In-implanted Cu single crystals was investigated by simultaneous perturbed γγ-angular correlation (PAC) and conversion-electron channeling measurements during annealing in the temperature range 300 to 900 K. Below 600 K different He-defect complexes were formed with large fractions of In probe atoms, which are increasing with annealing temperature. No significant displacements of substitutional In atoms occur, however, as concluded from the unchanged electron channeling effects. Above 700 K the channeling effects vanish completely, but a unique quadrupole interaction is observed in the PAC spectra for a large part (25-40%) of the probe atoms. It is proposed that He bubble growth is responsible for the vanishing of the channeling effects and that In atoms are attached to these bubbles on a unique, well-defined site.

ISSN:0033-7579    

DOI:10.1080/00337578708221236

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Abromeit and Poerschke measured radiation enhanced diffusion rates in alpha-brass which were much larger than those we obtained previously under similar irradiation conditions. They state that these discrepancies are due to the large impurity levels of our materials and that, consequently, the interpretation of our data can also be disregarded. They did not notice that i) the materials used in both laboratories were of similar purity and that, ii) the additional enhancement of radiation enhanced diffusion they were reporting is caused by dislocations introduced during mounting in well annealed specimens. This additional enhancement of diffusion is a kind of intrinsic phenomenon and has been carefully studied on alpha copper-aluminium alloys recently.

ISSN:0033-7579    

DOI:10.1080/00337578708221237

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

After an analysis of published experimental results and theoretical models on irradiation creep, the authors of a recent paper [1] conclude that “the strain accumulated in the material of the first wall of fusion reactors due to creep under pulsed irradiation… can reach a inadmissible high level”. This conclusion was reached since recent experimental results [2, 3] have been omitted from the analysis and incorrect input parameters for the theoretical models have been assumed.

ISSN:0033-7579    

DOI:10.1080/00337578708221238

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Using the ACAT code, the bombarding angle-dependence of sputtering yields has been investigated under various surface conditions. Three different models of rough surfaces are employed: (1) the rough surface with randomly distributed vacancies at the topmost layer, (2) the rectangluar-step surface, and (3) the oblique-step surface with the same inclined angle as the angle of incidence. It is found that the ion-bombardment-induced surface roughness greatly influences the bombarding-angle dependences of both the sputtering yield and the particle reflection coefficient. Due to the surface roughness the surface scattering is reduced and this effect results in the shift of the bombarding angle for the maximum sputtering yield to a higher angle of incidence.

ISSN:0033-7579    

DOI:10.1080/00337578708221239

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The calculation model of nucleation of large vacancy clusters in the cascade damage zone formed by means of some mechanisms of spatial vacancy rearrangements in the cooling stage of the energetic cascades has been proposed. Using the Monte-Carlo method, the model describes the clustering of monovacancies, divacancies and larger vacancy clusters migrating in the nonhomogeneous temperature field of the thermal spike (TS).

ISSN:0033-7579    

DOI:10.1080/00337578708221240

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The impurity interstitial interactions in diluteW57Co alloys during 3 MeV electron irradiation at 80 K and subsequent isochronal annealing have been studied using Mössbauer technique and electrical resistivity measurements. During 80 K irradiation, the population of one57Co impurity single interstitial complex, two different trapping sites for di-interstitials and three57Co impurity interstitial cluster complexes could be identified by the appearance of six additional absorption lines in the Mössbauer spectra with isomer shifts of +0.72 to +0.41 mm/s relative to the substitutional line and quadrupol splittings ranging from 1.89 to 0.17 mm/s. The trapping behaviour ofW57Co could be described by a nucleation trap model using a trapping radius ratioro/rv. = 0.25 (57Co atom without captured interstitial/vacancy) and assuming an increase of the trapping radius per trapped interstitial ΔLr = r0. Comparing the Mössbauer data and the resistivity data, we found that on an average only about 23% of the interstitials are trapped in the direct vicinity of the57Co impurities, while about 77% are bound farther on shallow traps.

ISSN:0033-7579    

DOI:10.1080/00337578708221241

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A new edge emission at 454.7nm has been observed in ZnSe crystals implanted with argon and subsequently annealed at 500°C in vacuum. Because this emission was also produced by irradiation of ZnSe with electrons of sufficient energy to displace zinc atoms, and because of its energy, it is attrihuted to Vznacceptor defects. In addition, two new bands peaking at 452.3 and 453.8 nm were found in ZnSe implanted with erbium ions and subsequently annealed at 600°C in vacuum. Annealing at 400°C in vacuum after silver implantation or indium implantation revealed new bands at 451.9 or 452.9 nm respectively. The bands at 452.3, 453.8, 451.9 and 452.9 nrn are believed to be related to complex acceptor centres which also involve zinc vacancies.

ISSN:0033-7579    

DOI:10.1080/00337578708221242

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A critical review of the numerous results on range profiles obtained with our Monte Carlo code TRIM (in its latest version) showed that there exist several, as yet unknown, universal relations between the moments of range and damage profiles. In combination with the well-known PRAL algorithm or other recently developed analytical formulae for the energy-range relation, one may use these relations to obtain improved range and damage profile predictions with a pocket calculator. For dominant nuclear and dominant electronic interactions mostly different relations are found. The influence of the surface on the moments is smaller than commonly assumed.

ISSN:0033-7579    

DOI:10.1080/00337578708221243

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Damage caused by low energy helium implantation in nickel and copper has been investigated for the first time by glancing angle X-ray diffraction technique. The damage confined only to the near surface region, typically few thousands Å, comprises of displacement type damage and implanted species. As X-ray penetration depth (for 99% absorption) can be continuously varied as a function of angle of incidence and X-ray wavelength, accurate lattice parameter measurements (back-reflection) can be used to obtain cumulative information regarding long- and short-range strain field of defects. High purity nickel and copper foils were irradiated at room temperature with 100 keV helium ions to fluence levels ranging from 1016to 1018ions/cm2. The results show: (a) simultaneous presence of two defect complexes of opposite strain field character in both nickel and copper, (b) mobility of vacancies is an important parameter for determining the nature and the strength of defect complex, and (c) local strains due to helium bubbles are considerably relieved after a certain dose in both nickel and copper.

ISSN:0033-7579    

DOI:10.1080/00337578708221244

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Thermal fading of the tracks in solid state nuclear track detectors (SSNTD) is observed in many applications where these detectors are used at elevated temperatures. In the present investigations, annealing out of the252Cf fission fragment tracks has been studied in sodalime glass in the temperature range 32-500°C. The damage trails disappear in the glass samples annealed at 500°C for 10 min and etched for 30 min in 4.8% HF at room temperature. Preannealing etching of 1 min duration renders the subsequent annealing at 500°C for 10 min ineffective and the tracks appear on further etching. Activation energy for the disappearance of the tracks comes out to be 0.6 eV. A vacancy diffusion mechanism responsible for track annealing has been suggested. Diffusion coefficient of 3.1 ± 0.51 × 10−7cm2/sec has been estimated.

ISSN:0033-7579    

DOI:10.1080/00337578708221245

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor