摘要:

A method of calculation of the random fractionXR(l) in a disordered channel containing host and foreign atoms is described. According to this method dechanneling caused by single scattering as well as multiple scattering at defects is calculated taking into account positions of the selfinterstitials and foreign atoms with respect to the lattice rows. The results demonstrate that the transverse energy distribution, flux peaking and, hence,XR(l) and depth profiles of defectsc(l) depend drastically on the defect position, concentration of implanted atoms, their position and the rechanneling process. The method is applied to experimental data for GaAs irradiated by He+and N-implanted Si. The obtainedXR(l) andc(l) are compared with those obtained using other methods.

ISSN:0033-7579    

DOI:10.1080/00337578408206066

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The paper considers radiation of ultrarelativistic electrons in axial channeling initially predicted by Kumakhov.3The consideration is based on the results of solution of the Fokker-Planck equation.28The spectral-angular characteristics of the Kumakhov radiation in thick single crystals are calculated. It is shown that in heavy single crystals the energy losses on radiation can amount to a considerable portion of the initial beam energy. The possibility of a sharp increase of radiation due to a decrease of crystal temperature is discussed. It is shown that radiation intensity in axial channeling is weakly dependent on the initial angle of the electron entrance into the channel if this angle changes within the limits of a critical one.

ISSN:0033-7579    

DOI:10.1080/00337578408206067

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The influence of the non-dipole character of radiation on the spectral characteristics of the Kumakhov radiation has been analysed. It was shown that if γψL≦ 1, the non-dipole character can lead to an increase of the spectral intensity of radiation in its maximum. In heavy crystals the strong non-dipole character of radiation γψL> 1 leads to sharply expressed maximum in spectral distribution of the radiated energy. The influence of the non-dipole character on the temperature dependence of radiation is investigated.

ISSN:0033-7579    

DOI:10.1080/00337578408206068

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Ion beam mixing of Yb coated nickel films has been studied using Kr+and O2+bombardment. The use of a nickel overlayer was found to be effective in protecting the films from oxidation. By assuming the validity of a simple solution of the diffusion equation, effective diffusion coefficients at different Kr+bombardment temperatures were obtained for Yb/Ni mixing. The diffusion was linear with an apparent activation energy of (0.18±0.03) eV. This result is discussed in the light of radiation enhdnced diffusion and cascade mixing theory. No mixing was observed with O2+ bombardment. This indicates that the chemical nature of the ions used is of importance and it is suggested that trapping of oxygen atoms in the impurity film is responsible for this effect.

ISSN:0033-7579    

DOI:10.1080/00337578408206069

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The measurement of the stopping powers and stragglings for 8–300 keV protons in C, Al and Au complete the series of measurements performed with heavy ions under identical conditions. Effective-charge fractions, unaffected by target-thickness uncertainties, are derived and compared to the current theory of Brandt and Kitagawa. The energy-loss stragglings of protons are in good agreement with the Bonderup-Hvelplund theory, whereas the energy-loss stragglings of heavy ions exceed the theoretical predictions. It confirms the influence of non-equilibrium regions of targets on the results of energy-loss experiments performed with slow ions which we observed before.

ISSN:0033-7579    

DOI:10.1080/00337578408206070

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Internal friction and elastic modulus measurements of Cr single crystal after fast neutron irradiation at 5–7 K are made as a function of temperature. The recovery stages are also studied by electrical resistivity measurements.

ISSN:0033-7579    

DOI:10.1080/00337578408206071

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Internal friction and elastic modulus measurements of AI-0.07 at.% Mg single crystal after fast neutron irradiation at 5–7 K are made as a function of temperature. The recovery stages are also studied by electrical resistivity measurements and compared with that of pure Al. Several internal friction peaks and elastic modulus changes due to dislocation pinning are observed. The peaks, observed only in the alloy, could be related to the reorientation of interstitial-solute atom complexes. Symmetry and annealing processes of interstitials and interstitial-solute atom complexes are discussed using ⟨111⟩ and ⟨100⟩ oriented specimens. The relaxation strengths and the activation energies for these peaks are also given.

ISSN:0033-7579    

DOI:10.1080/00337578408206072

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The damage induced by low-temperature proton irradiation in amorphous Pd80Si20prepared by ion implantation is studied via electrical resistivity measurements. Our experimental results concerning the initial damage rate and the resistivity saturation are compared to the results obtained for electron and high energy16O irradiation of amorphous Pd80Si20quenched from the melt. The resistivity curve is analyzed in terms of irradiation-induced “point defects”.

ISSN:0033-7579    

DOI:10.1080/00337578408206073

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Photovoltaïc parameters, minority carrier lifetime and defect characterization have been used to study the degradation of P/N lithium-doped solar-cells irradiated by 1 MeV electrons. This work points out that A centers ([V-01 complexes) and divancancies play a dominant role in the degradation of the cells. Annealing studies in conditions similar to the space conditions show that an important recovery of the cell parameters can be obtained. A rapid disappearance of both A centers and divancancies is observed and a new defect presumably associated with lithium (ΔE=Ec-0.36 eV; σn≈2.10−16cm2) forms simultaneoulsy.

ISSN:0033-7579    

DOI:10.1080/00337578408206074

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Silver and silver-zinc alloys with 5, 10, 20, 25 and 30 at.% Zn were irradiated with 3 MeV electrons at 4.7 K and isochronally annealed up to 573 K. The initial rate of resistivity increase with irradiation dose increases linearly with the Zn concentration. Stage I is strongly suppressed in the concentrated alloys. The first pronounced recovery stage is stage III. This is in agreement with the model proposed by Halbwachs, Hillairet and coworkers that inAgZnthe vacancies are more mobile than the interstitials. The annihilating vacancies change the short-range order of the alloys reducing by this the resistivity far below the value prior to the irradiation. This effect is independent of the irradiation dose, indicating a reaction of second order in stage III. Above 400 K the resistivity of the alloys increases drastically when thermal vacancies contribute in the disordering of the alloys.

ISSN:0033-7579    

DOI:10.1080/00337578408206075

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor