摘要:

The yield for molecular ions desorbed from a valine sample has been measured as a function of the charge state of the incident fast heavy ions. The data can be interpreted in the following way: (i) the yield depends on the square of the primary ion charge, and (ii) desorption takes place not only at the sample surface but also within a layer underneath. The depth of this layer is smaller than the depth needed to achieve charge state equilibrium for the primary ions.

ISSN:0033-7579    

DOI:10.1080/00337578408215795

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Isochronal annealing studies on alpha-irradiated nickel specimens have been performed via the positron annihilation technique using both the Doppler broadening and life-time measurement methods. A two-state trapping model favours the presence of dislocation loops and vacancy clusters like microvoids in the irradiated specimens. The decrease of the positron parameters between 400 and 650 K has been associated with He trapping by vacancy-type defects and He-vacancy complex formation. Above 650 K stabilization of this complex has been observed. The results agree with the model where the He atoms, though initially at interstitial sites, quickly interact with vacancy-type defects and relax to substitutional positions. Present observations favour the idea that a He atom in a metal vacancy (substitutional) acts as a trapping site for positrons.

ISSN:0033-7579    

DOI:10.1080/00337578408215796

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Heavy ions from all groups of the periodic system have been implanted at keV energies into Si at room temperature. The samples have been analyzed in their as-implanted state by high resolution ion backscattering of 0.5 MeV 4He ions. The results show that only elements from groups IIIa, IVa and Va have dominant substitutional occupation, whereas in all other cases interstitial sites are largely preferred. It is concluded that chemical effects govern the selection of lattice sites.

ISSN:0033-7579    

DOI:10.1080/00337578408215797

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Sintered pellets ofCeO2 and UO2, as well as PuO2 powder, have been irradiated with alpha particles emitted from an effectively semi-infinite 238PuO2 source. The lattice parameters of all three materials increased with dose,Dα, according to the expression δa/a0=A[1—exp(—BDα)], in agreement with a previously developed model. The recovery behavior of the lattice defects has been studied by isochronal annealing. Two recovery stages were observed in the temperature range between 50 and 1000°C for each material, and the activation energies were estimated based on previous single crystal studies. Comparisons with self-damage from alpha decay are made, and the behavior of the lattice defects is discussed.

ISSN:0033-7579    

DOI:10.1080/00337578408215798

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337578408215799

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor