摘要:

Different dilute Al-Ge and Al-Ga alloys, of Ge and Ga from 200 to 20,000 ppm, have been irradiated in the reactor at helium temperature. The total neutron dose was 1.5 × 1018n/cm2.

ISSN:0033-7579    

DOI:10.1080/00337577608237440

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The backscattering-channeling method was used to investigate the interactions between irradiation-induced defects and solute atoms of Ag, Sb and Au in dilute copper alloys. Since the solute atoms were not displaced appreciably from lattice sites by irradiation with ∼10161.5 MeV He+ions/cm2at 40 or 70 K, it is concluded that the Cu self- interstitials created by the irradiation retained their identity when trapped by the solute atoms. During subsequent annealing between 180 and 270 K, the solute atoms were displaced from lattice sites. The irradiation-induced increase in dechanneling recovered only ∼30% in this temperature range. Further low temperature irradiations reduced the solute atom displacements. These results are consistent with multiple trapping of vacancies at the solute atoms.

ISSN:0033-7579    

DOI:10.1080/00337577608237441

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The intensity/time plots of the photon emission of excited Na atoms recorded during the continuous removal of thin Na2O-containing glassy layers by an ion beam allow for the analysis of the Na2O concentration profiles in these layers. Different intensity/time plots were obtained when changing the angle of incidence β of the ions or applying different constant β during the ablation of thin Na2O-containing glassy layers by positive 5.6 keV Ne+, Ar+and Xe+ions. These differences indicated that the concentration of Na is changed by a drift of Na+ions caused by a positive space charge below the ion-bombarded surface. The field strength of the space charge was greatest for Ne+ions, smallest for Xe+ions. Simultaneously, a repulsive or an attractive field strength acts on positive Na ions within the thin layer if the value of the dielectric constant e in the thin layer is greater or smaller than in the substrate respectively. The influence of the drift on the profiles could be separated from that of the disintegration of Na at the surface and the displacements of Na in the collision cascade reported earlier. For glasses containing the oxides of heavy elements, an additional influence of the back-scattering of Na atoms moved in the collision cascade from the interface between the glass substrates and layers on the intensity/time curves was also observed for Xe+ions. The shapes of the recorded Na profiles are distinctly different for different stimulation depth distributions of the projectile ions. The different spatial extensions of the stimulation depths for Na moved in the collision cascade below the surface were estimated for 5.6 keV Xe+ions at β = 20° and β = 70°. The consequences of the various findings for the quantitative analysis by ion-beam-induced radiation are considered.

ISSN:0033-7579    

DOI:10.1080/00337577608237442

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Channeling effect measurements using MeV4He ions were used in the study of the anneal of implantation disorder in <111> Si. The Si was implanted at LN2temperature with arsenic or boron to dose levels sufficient for the formation of amorphous layers. We found that the residual disorder depends upon the previous annealing procedures. Samples annealed directly at temperatures up to 950°C exhibited high levels of disorder. The measurements suggest that the disordered layers can contain regions misoriented at small angles to the original substrate. Samples with sequential anneals from 450 up to 950 in 100°C increments, were essentially damage free from channeling viewpoint. We suggest that this thermal history is responsible for of some of the conflicting viewpoints in the literature.

ISSN:0033-7579    

DOI:10.1080/00337577608237443

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The attachment behaviour of xenon and krypton following (n, γ) events on sintered thoria powders of particle size 105–125 μm, 63–75 μm, 37–45 μm and less than 10 μm has been studied at different gas pressure ranging from 9.33 × 102to 6.67 × 104Pa. The attachment efficiency of Xe-125 is maximum compared to other isotopes of xenon. It has been observed that for powders of particle size less than 10 μm, the attachment efficiency is independent of gas pressure, but for larger particle size it decreases at higher pressures (> 4 × 104Pa).

ISSN:0033-7579    

DOI:10.1080/00337577608237444

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

The results of experimental study of 30 keV energy argon ions scattering by the (100) face of a copper crystal are presented. Measurements have been made in a wide range of azimuthal angles of target rotation. The relationship between the ion focussing effect and the channelling effect is discussed.

ISSN:0033-7579    

DOI:10.1080/00337577608237445

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

It is well known that radiation (both particle and photon) can cause substantial density changes in certain solids. In cases where the radiation damage is non-uniformly distributed, these changes are manifested as gradients of residual stress. With ion bombardment, where penetrations under accelerating voltages of several hundred thousand volts are typically on the micrometre scale, one may reasonably describe the mechanical damage in terms of a lateral “surface stress.” Now if the irradiated material is brittle, the possibility exists of such stresses causing incipient surface flaws (so-called Griffith flaws, present in abundance on all typical brittle surfaces)1to grow into dangerous large-scale cracks. Measurements on a number of brittle solids2–6reveal a general tendency for the level of radiation-induced surface stress to increase steadily with fluence up to a maximum, beyond which saturation (or even decline) sets in. Of the solids investigated, fused is unique in that the surface stress is tensile, indicative of a structural compaction; silicate glasses might accordingly be expected to show a particularly high susceptibility to radiation-enhanced cracking.

ISSN:0033-7579    

DOI:10.1080/00337577608237446

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

Bombardment-induced structural changes in non-metallic solids are known to occur in three forms: amorphization, crystallization or stoichiometry changes. A versatile technique to study the formation and annealing of structural changes is to produce the damage with rare gas ions and to use the release of these rare gas ions as a probe for damage annealing.1Other techniques include electron diffraction,1measurement of range profiles,2of solubility3or electrical conductivity.4

ISSN:0033-7579    

DOI:10.1080/00337577608237447

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor

摘要:

It is generally meaningless to extract a measurement of the “number of disordered atoms” from a backscattering experiment. The only case where this is a measurable quantity is that of amorphous regions imbedded in a perfect crystal. In all other cases (particularly in metals), a backscattering experiment can yield only an indication about the degree of lattice disorder.

ISSN:0033-7579    

DOI:10.1080/00337577608237448

出版商:Taylor & Francis Group    

年代:1976

数据来源: Taylor