摘要:

The analytical expression for the sputtering yield of fine-grained targets by heavy multicharged ions derived previously by the authors is discussed. Experimental yields are given for the sputtering of fine-grained islet-like gold layers and for bulk gold foil by 45–65 MeV fission fragments. A comparison of the experimental yields with those obtained by calculation is made. Existing models of sputtering of targets by heavy multicharged ions are considered. Some assumptions on the sputtering mechanism are made.

ISSN:0033-7579    

DOI:10.1080/00337578308207391

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A model of replacement sequence (RS) evolution in a crystal has been developed. The calculation results of the RS characteristics are compared with the data obtained by the molecular dynamics method. The estimations of the temperature effect on the RS mean lengths showed that this effect is small; at least up to 500 K.

ISSN:0033-7579    

DOI:10.1080/00337578308207392

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The passivation of argon sputter-etch induced electrically active defects on Ge, Si, and GaAs surfaces by reaction with atomic hydrogen has been observed using deep level transient spectroscopy. A broad band of defect states, giving rise to non-linear Arrhenius plots, appears to be associated with the induced damage centres. Forn-type Ge andp-type Si, a 20-min exposure to atomic hydrogen at 180°C is shown to neutralize the damage created by a 5-min, 6 kV (DC), Ar gas sputter-etch. Forn-type GaAs a 1-h exposure at 250°C was sufficient, whilstn-type Si required a 1-h exposure to the hydrogen plasma at 300°C to passivate the damage. In each case, to remove the sputter-etch damage by thermal annealing required temperatures approximately 100°C higher, for periods of approximately 2 h.

ISSN:0033-7579    

DOI:10.1080/00337578308207393

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Transformation behaviour in thin foils of a Ni-12 at.% Ti alloy was investigated by means ofin situaging and electron irradiation experiments inside a high voltage electron microscope. It is shown experimentally that the mode or the morphology of precipitation and ordering reactions in the thin foils differ somewhat from that observed in the bulk material. In the thicker part of the thin foils agedin situat 873–973 K, a periodic modulated structure is observed to consist of a periodic array of cuboidal coherent particles along the [100] crystallographic directions. The development of ordering within the solute enriched particles appears to be much slower than in the bulk specimen In the thinner part of the foil or in the near-surface regions, no precipitation or ordering occurs and so-called precipitate-free zones (PFZs) are observed. At a higher temperature of 1073 K, precipitation takes place preferentially at the foil surfaces Electron irradiation at elevated temperatures is found to disturb the formation and growth of a metastable modulated structure. and alter the distribution and the morphology of precipitate particles initially present.

ISSN:0033-7579    

DOI:10.1080/00337578308207394

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A new approximation for the continuous interaction potentials of atomic planes and strings with channeled electrons and positrons in crystals is proposed. A model in which atomic electron distributions within a certain atomic subshell are assumed to be exponentially decaying is used. Contrary to the Thomas-Fermi (TF) and Thomas-Fermi-Dirac (TFD) models this approach takes into account the shell structure of atoms in reasonably good agreement with the Hartree-Fock method (HF). Simple analytical expressions for the continuous plane (string) potentials are given. Calculations of several planar potentials for positrons channeled in silicon and tungsten are presented. Results are compared with widely known Lindhard and Molière approximations. Some estimates of the Kumakhov spontaneous radiation intensity under positron planar channeling conditions in the classical approximation are also given.

ISSN:0033-7579    

DOI:10.1080/00337578308207395

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The effect of electron irradiation with an energy of 1.0–2.3 MeV on the structure-phase stability of austenitic chromium-nickel and chromium-manganese stainless steels has been studied. It is shown that following electron irradiation with a displacement rate of about 10−8dpa/s minor clusters of atoms (with an average magnitude of ∼60 Å) occur in SS316L and EP838 stainless steels. These clusters may be seen with the help of small-angle X-ray scattering and electron microscopy. Their formation process is subject to thermal activation and is accompanied by growth of the specific electrical resistance. The activation energy of this process has been determined to be 0.30 and 0.33 eV for EP838 and SS316L steels, respectively. Thermal ageing activation energies in these steels are 0.53 and 0.59 eV, respectively. Additionalin situirradiation with high rate electrons (∼10−3dpa/s) in a high voltage electron microscope up to a rate of 0.2 dpa resulted in precipitate coarsening and in partial growth of the above clusters (segregations or G.P. zones) up to a magnitude of 150–200 Å. The volume density of the clusters following the additional irradiation was about ∼0.2%.

ISSN:0033-7579    

DOI:10.1080/00337578308207396

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Computer simulation methods have been used to study threshold radiation damage structures in rutile. It was found Ti ions have threshold energies much larger than O ions. Basal plane displacements for oxygen were shown to be complex, and focuson behaviour was only found at energies several times the threshold energy. Oxygen ions do not have simple interstitials or vacancies, but rather a three-ion crowdion and divacancy-interstitial combination were found, respectively. Threshold energies were found to be highly dependent on crystallographic direction, being as low as 10 eV in one instance, but often much higher. Oxygen ions were seen to defocus along thec-axis.

ISSN:0033-7579    

DOI:10.1080/00337578308207397

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

High purity iron (residual resistance ratio ∼5000) and similar iron doped with carbon (15 at. ppm and 67 at.ppm) have been irradiated with 3 MeV electrons at low temperatures. The resistivity recovery of these specimens has been investigated in some detail.

ISSN:0033-7579    

DOI:10.1080/00337578308207398

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The defects in n-GaP crystals irradiated by 2.3 MeV electrons up to 1 × 1019cm−2at RT were studied by means of positron annihilation (angular correlation) and electrical property measurements. It was found that positrons are trapped in some radiation-induced vacancy-type defects (acceptors) but that the effect saturates at high electron fluences (D1 × 1018cm−2). The trapping rate in irradiated samples increases with temperature in the range 77–300 K. Post-irradiation isochronal annealing reveals the positron traps clustering at about 200–280°C. All positron sensitive radiation-induced defects disappear upon annealing up to 500°C.

ISSN:0033-7579    

DOI:10.1080/00337578308207399

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A computer simulation of low energy implantation is presented. The method of calculation takes into account the inelastic processes and vacancies in the crystal lattice.

ISSN:0033-7579    

DOI:10.1080/00337578308207400

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor