摘要:

The association of optical absorption, channeling and conversion electron Mössbauer techniques has been applied to the study of high dose iron implantation (6 × 101657Fe+.cm−2) phenomena in MgO single crystals. After implantation defects in the oxygen sublattice (F-type centers) and in the magnesium sublattice (V−-centers) have been observed as well as superparamagnetic iron precipitates (size ∽20 Å) and Fe2+ions. After thermal annealing for one hour at 700°C in argon atmosphere, all the iron species are converted mainly into Fe3+ions contributing to the stabilization of F-type centers. A part of them is magnetically ordered even at room temperature, the other remaining paramagnetic down to 4.2 K. This could correspond to a bipartition in the Fe2O3particle sizes: 50 to 80 Å and <20 Å respectively. Preliminary results in LiF implanted with 2 × 101657Fe+ions. cm−2are also reported

ISSN:0033-7579    

DOI:10.1080/00337578008210024

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The influence of the anisotropy of the momentum recoil density of collision cascades in solids on the energy and angular distribution of sputtered particles is considered. Various sputtering mechanisms are discussed. For some of those mechanisms this anisotropy leads to deviations from a ε−2asymptotic form in the energy distribution and to an asymmetry in the angular distribution as a function of the angle of incidence of the projectile.

ISSN:0033-7579    

DOI:10.1080/00337578008210025

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Radiation initiated post-polymerisation of trioxane has been studied by irradiating the super dry monomer at dry ice temperature and annealing them at higher temperatures. The mode of termination is presumed to be predominantly by chain transfer to the monomer. Kinetic expression has been derived for the same. Using the rate constant ratioktr/kpfrom the data on in-source polymerisation the molecular weights were calculated to be of the order of 3.6 × 105. This was experimentally observed for various conversions.

ISSN:0033-7579    

DOI:10.1080/00337578008210026

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

By means of IR-absorption measurements the dose dependencies of the concentrations of vacancy-oxygen complexes (VO), interstitial oxygen atoms (QI), substitutional carbon atoms (CS) and interstitial carbon-oxygen complexes (CIOI) inn- andp-type silicon irradiated with 1.1 MeV electrons have been investigated. The observed increase of the production rate of VO-complexes with the rise of carbon and boron atoms concentrations (these impurities act as sinks for silicon interstitial atoms) has been explained in terms of annihilation of the vacancies and interstitials on the oxygen atoms. The results obtained show that boron atoms are more effective sinks than carbon atoms for the interstitial silicon atoms. That seems to be connected not only with the higher probability of boron injection into interstitial position but also with the further capture of interstitial silicon atoms on the interstitial boron. i.e. with the interstitial cluster formation.

ISSN:0033-7579    

DOI:10.1080/00337578008210027

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The physical fact that diamond is electrically insulating while amorphous carbon and graphite are conducting is used in the present work to study the local damage that each implanted ion creates around its track and to conclude about the processes through which implanted diamond turns amorphous. Experimental data for the conductivity of Sb implanted diamond for various gometries, energies and doses are analyzed by the use of percolation theory. It seems that the amorphization of implanted diamond proceeds gradually with no well defined amorphous regions formed around the ion track. Amorphization in implanted diamond seems to occur in a way different than is believed to be the case for implanted silicon, where some direct amorphization around an ion track is suggested. This major difference can be attributed to the abnormally large change in densities between diamond and amorphous carbon or graphite which suppresses the growth of local amorphous regions in diamond.

ISSN:0033-7579    

DOI:10.1080/00337578008210028

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Theoretical considerations are presented which deal with the possibility of application of contactless microwave conductivity measurements in the studies of implantation effects. It is shown that, to certain extent, microwave measurements can serve as easy and practical testing method complementary to other measuring techniques. Practical formulae for dielectric constant and sheet resistivity determination are given and the applicability range of the method is estimated.

ISSN:0033-7579    

DOI:10.1080/00337578008210029

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A theory of the diffusion interaction of vacancy voids in a many-particle system, i.e. that consisting of N-voids is constructed. The void interaction results from the diffusion exchange of point defects, which are present in the concentration cloud around every void. For a metal containing impurities, dislocations etc. an expression for the growth rate of an individual void of an arbitrary size is obtained within the framework of this model, taking into account the effect of the other voids in it. It is shown that the diffusion interaction in the void system has a certain screening radius, which depends on the total number of voids and additional sinks for point defects in a metal. Using the diffusion interaction of the vacancy voids we have studied the kinetic stability of the lattice void distribution both under continuous irradiation and ordinary temperature annealing. The criterion for the existence of a stable lattice of vacancy voids is obtained in a real crystal containing dislocations and impurity atoms under irradiation conditions. In the void lattice instability range the laws governing the variation in the average void size and dispersion of the void size distribution in a lattice are derived. The estimates of the typical void lattice instability time are presented.

ISSN:0033-7579    

DOI:10.1080/00337578008210030

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Recent experiments on the erosion of condensed gases and alkali halides by incident ions have renewed interest in the description of thermal spikes. In such spikes a localized, transiently heated region produced by incident radiation may induce activated processes like evaporation of atoms or molecules from a surface. In this paper are presented useful expressions to describe the thermal sputtering for materials having a temperature dependent thermal diffusivity, using a heat capacity and thermal conductivity which vary asC=C0Tn–1andK=K0m–1, respectively, and assigning a width to the initial temperature distribution.

ISSN:0033-7579    

DOI:10.1080/00337578008210031

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The method of electron Auger-spectrometry is used to study the composition of the sputtered A(111) and B(―1―1―1) faces of InSb dendrites and the deposits sputtered from them. The obtained noticeable anisotropy of the In and Sb distribution within ejection angles ± 50° to <111> directions has been found to be in good qualitative agreement with the results of computer calculations. It has been shown that the observed compositions of the dendrites and films vary depending on sputtering time.

ISSN:0033-7579    

DOI:10.1080/00337578008210032

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A velocity spectrum of neutral sputtered particles as well as a low resolution mass spectrum of sputtered molecular ions has been measured for 4.74 MeV19F+2incident on UF4. The velocity spectrum is dramatically different from spectra taken with low energy (keV) bombarding ions, and is shown to be consistent with a hot plasma of atoms in thermal equilibrium inside the target. We propose a “thermalized ion explosion” model for high energy sputtering which is also expected to describe track formation in dielectric materials. The model is shown to be consistent with the observed total sputtering yield and the dependence of the yield on the primary ionization rate of the incident ion.

ISSN:0033-7579    

DOI:10.1080/00337578008210033

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor