摘要:

Radioactive111In-ions were implanted at 400 keV into polycrystalline Al-foils at a maximum concentration of ≤ 10 ppm and a mean depth of 160 nm. In addition, 1016/cm2inert gas ions were implanted partially overlapping with the111In-profile (Xe: 600 keV, Kr: 450 keV, He: 30 keV). Depth profiling of the Xe- or Kr-ions was performed by 900 keV α-Rutherford Backscattering (RBS). Perturbed Angular Correlation (PAC) measurements showed after the inert gas implantation a 40–70% fraction of a well-defined electric field gradient withvQ= 144.4(5) MHz and η = 0.12(2) which agrees with former results for111In-cavity complexes in Al after Ar- and He- irradiations. The fraction depends on the overlap of the implanted In- and inert-gas profiles, the sequence of the ion irradiations, and the heat treatment. The maximum fraction was found after annealing at 200°C. The influence of the111In-correlated damage and the thermal stability of the cavities were investigated.

ISSN:1042-0150    

DOI:10.1080/10420159608211537

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Positron annihilation studies were carried out on single and polycrystals of Zn1−xCuxCr2Se4spinels. The largest average positron lifetime is observed for the single crystals, suggesting that for the spinel structure single crystals contain more vacancies than polycrystals. The positron lifetime connected with vacancies increases with x (copper concentration) as long as the crystals are semiconducting and decreases with x in the metallic region. These effects are probably caused by the different electron densities in the semiconducting and metallic regions of the Zn1−xCuxCr2Se4spinel series together with different vacancy concentrations. In particular, the results are in good agreement with a vacancy model which allows to calculate the vacancy concentration using a single vacancy parameter.

ISSN:1042-0150    

DOI:10.1080/10420159608211538

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A method for displacement damage rate calculations in compound materials under neutron and ion accelerator irradiation is proposed. The method is especially suitable for materials with significantly different masses of species. Range and damage depth profiles in HTSC ceramics for different He-ion projectile energies were calculated. Partial contributions of each species to displacement damage and spectral-averaged partial damage cross sections for two neutron irradiation conditions were also calculated. The developed code provides a quick and reliable way of comparison of the displacement damage under neutron and ion irradiation. Helium ion doses equivalent by dpa to neutron irradiation in ORR and YAYOI reactors were obtained.

ISSN:1042-0150    

DOI:10.1080/10420159608211539

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper we will consider the disorder in some cubic solid solutions consisting of one of the alkaline earth fluorides and one of the rare earth fluorides. This is an attractive group of model materials, because these materials have a rather simple overall cubic structure. We will discuss the most important features of the structure of these solid solutions, which have been obtained using various spectroscopic methods. From these experiments we will conclude that, depending on the radii of the ions in the host alkaline earth fluoride crystal and the trivalent impurities the defect structure varies significantly. In some solid solutions evidence for appreciable preferential clustering has been found. On the other hand there is substantial evidence that for some other materials there is little or no preference towards clustering for impurity concentrations upto even a few mol%; here, the defect structure is determined more or less by statistics.

ISSN:1042-0150    

DOI:10.1080/10420159608211540

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

First, a screw dislocation in an infinite medium is analyzed by the theory of nonlocal elasticity. Then, the nonlocal elastic interaction energy between a screw dislocation and a point defect caused by an interstitial carbon in bcc iron is calculated. The results show very different conclusions between the nonlocal solutions and the classical ones. The value of the elastic interaction energy obtained by nonlocal elasticity has a good agreement with that measured by a method of internal friction. The classical value, however, is greater than the experimental value.

ISSN:1042-0150    

DOI:10.1080/10420159608211541

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The effect of gamma-irradiation on the absorption optical spectra of telluric acid ammonium phosphate single crystals (TAAP) has been studied, in the wave length of 200–600 nm, for samples irradiated by various doses up to 10 Mrad. The results show that the electron phonon coupling constant increases with the irradiation dose.

ISSN:1042-0150    

DOI:10.1080/10420159608211542

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In the present work, CR-39 plastic detectors have been used in alpha and neutron detection studies. Detectors were first treated chemically, before irradiation, for background reduction and registration efficiency improvement. CR-39 detectors etched pre-chemically in 6.25N NaOH solution at 70°C for 10 h were found to be necessary to minimize the background tracks.

ISSN:1042-0150    

DOI:10.1080/10420159608211543

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor