摘要:

An interatomic potential proposed recently in connection with some planar channelling calculations has been examined with regards to its predictions for the quantities of interest in axial channeling, such as string potential and critical angles. The simplicity of this potential has been found to be of great use in connection with the calculations on effects of dislocations on the energy loss of channelled ions. The quantities of interest in dechannelling, both axial and planar, have also been calculated and compared with those obtained using Lindhard′s potential.

ISSN:0033-7579    

DOI:10.1080/00337577608240821

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The integro-differential equations for moments of range and energy-deposition distributions of heavy ions implanted into amorphous targets are solved by an improved method, allowing accuracy to be retained to higher energies. Correlation of electronic stopping with scattering is found to have negligible effects on the calculated distributions for those scattering cross sections for which uncorrelated-stopping calculations are meaningful; however inclusion of correlation allows a wider range of scattering potentials to be used in the calculations. Effects of varying this potential are explored and it is indicated that a careful study of the collision cascade could provide information about the potential.

ISSN:0033-7579    

DOI:10.1080/00337577608240822

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The proton radiation effects in ferrous chloride are studied by means of the Mössbauer spectroscopy. The irradiation with protons of energy of 0.68 to 1.5 MeV has been found to cause dehydration and chemical decomposition of ferrous chloride. FeCl2·2H2O, and Fe3O4in superparamagnetic and ferromagnetic states, as well as Fe1−xO were formed. The formation of a superparamagnetic phase of Fe3O4within the “spike” regions was verified by low temperature measurements. The effects observed were interpreted in terms of the “thermal spike” model. The calculated temperatures and radii of “spikes” formed by iron, chloride and oxygen ions are in good agreement with observation for superparamagnetic Fe3O4.

ISSN:0033-7579    

DOI:10.1080/00337577608240823

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Two natural semiconducting diamonds were pre-heated at 13SO°C, irradiated at 77°K with approximately 2 × 1016electrons/cm2at an energy of 1 MeV and heated for successively increasing periods of time at temperatures in the range 200 to 1200°C. The annealing of the irradiation damage exhibits at least three direct stages and one reverse stage. Direct and reverse annealing are defined as producing changes, respectively, in the opposite direction to, and in the same direction as, those produced by the irradiation damage.

ISSN:0033-7579    

DOI:10.1080/00337577608240824

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The importance of homogeneous and heterogeneous nucleation in the amorphization of silicon by ion implantation is considered. Previously a homogeneous model involving dose rate had been used to identify neutral vacancy and divacancy annealing as important mechanisms in the amorphization process. In an attempt to verify this dose rate model, experiments which detect the electron spin resonance signal from the amorphous regions have been performed. Both a light ion (N+) and a heavy ion (Kr+) at low (20 keV) and high (180 keV) energy were implanted into silicon at low (80°K) and higher (∼350°K) temperatures. No dose rate dependence was found, and the temperature dependence is not as predicted by the model. In addition, the production rate is not proportional to the dose to the one-half power-a power dependence which has previously been attributed to homogeneous nucleation. Furthermore, since the data agrees with the predictions of a heterogeneous model, it is concluded that homogeneous nucleation is not an important process in the amorphization of silicon by ion implantation.

ISSN:0033-7579    

DOI:10.1080/00337577608240825

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

An approximate analytic solution of the system of equations describing the kinetics of formation and the parameters of radiation defect clusters in crystals is obtained. A model corresponding to the real parameters of Si is assumed as a basis for calculation and it is shown that two types of secondary radiation defect clusters may be realized corresponding to the congealing and spreading of the initial vacancy clusters. The cluster type depends on the incident energy of the particle which creates the effects and on the physical parameters of the crystal under irradiation. For a congealing cluster most of the initial vacancies react within the original volume of the damage cascade and for a spreading cluster the final concentration of divacancies andA-centres within the original cascade volume is much less than the initial vacancy concentration, i.e. most of the vacancies form divacancies andA-centres dispersed throughout the crystal volume.

ISSN:0033-7579    

DOI:10.1080/00337577608240826

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The well-known effects of dissolved oxygen and hydrogen in respectively increasing and reducing the corrosion rate of zircaloys irradiated in high temperature water have been attributed to changes in the course of water radiolysis.1Computer simulation of the growth and decay of radioly tic species produced by β, γ and neutron irradiation of water at 25°C and 305°C has been performed. In general, neutron irradiation leads to greater decomposition of water, and the effect of dissolved oxygen at 305°C is to markedly increase the concentrations of oxidizing radiolytic species. Correlation of zircaloy corrosion behaviour under such conditions with predictions of water radiolysis suggests that either HO2of O−2are significant contributors to the corrosion enhancement phenomenon. Possible enhancement mechanisms are briefly discussed.

ISSN:0033-7579    

DOI:10.1080/00337577608240827

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Using electrical resistivity measurements the recovery of pure lead irradiated at low temperature with electrons has been investigated from 3 K up to 340 K as a function of electron dose and energy. Doping experiments have also been performed. The annealing behaviour of lead is similar to other fcc-metals, except gold. The recovery stage I at about 4 K (first reported by Birtcheret al.6clearly shows the separation of IDand IEdue to the correlated and un-correlated annealing of interstitials. After stage II (5 K to 120 K) the dose dependent recovery stage III has been observed at about 160 K. In this region the single-vacancies should migrate and anneal with an activation energy Qm1v= 0.43 ± 0.03 eV determined by the “change of slope” method. In the last recovery stage usually called stage V at about room temperature vacancy clusters should dissolve. The measured activation energy of this process is about 1.05 eV which is equal to the self-diffusion energy in lead.

ISSN:0033-7579    

DOI:10.1080/00337577608240828

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337577608240829

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337577608240830

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor