摘要:

The effect of α-recoil damage in natural zircon has been studied by infrared spectra of the silicate vibrations, single crystal x-ray diffraction, and polarized visible and near infrared spectra of absorptions due to tetravalent uranium. Contrary to some previously expressed views, α-recoil damage in natural zircon appears to be a progressive process, with increasing α-recoil dosage. No crystalline phases of zirconia or silica were detected by x-ray diffraction and measurements of U4+spectra, in any but some very severely damaged zircons. The end product, in the limit of very high α-recoil doses, would seem to be a glass, rather than a mixture of SiO2and ZrO2. The Si-O bonding in the glass would appear to be rather similar to that in vitreous SiO2.

ISSN:0033-7579    

DOI:10.1080/00337577508239470

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Temperature dependence of self-sputtering in germanium has been determined for the Ge (110), Ge (111) and Ge (100) surfaces. At room temperature the sputtering yield is 8 atoms/ion for all three surfaces bombarded by 50 keV Ge ions. At about 300°C the yield drops to 2.5 atoms/ion for the Ge (110) and Ge (111) surfaces and 2.9 atoms/ion for the Ge (100). The transition is caused by a change in the crystal order. A comparison with current sputtering theories is made.

ISSN:0033-7579    

DOI:10.1080/00337577508239471

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The internal friction and shear modulus of polycrystalline Al + 3 at.% Mg was studied as a function of temperature after fast neutron irradiation, at liquid nitrogen temperature (78 K). The initial increase of shear modulus after irradiation is mainly due to the dislocation pinning of the irradiation induced defects. The further increase of shear modulus during annealing is caused by the bulk-effect. The recovery of shear modulus up to room temperature is similar to that of the residual electrical resistivity after a low temperature neutron irradiation. However, we may point out that in contrast to stage II, in stage III we observe a recovery of shear modulus that is distinctly more pronounced than that of electrical resistivity. The temperature dependence of internal friction, before irradiation, shows a peak at 230 K. After neutron irradiation we observe no peak in the temperature region, from 90 K to 300 K.

ISSN:0033-7579    

DOI:10.1080/00337577508239472

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

High purity polycrystalline wires of β-tin have been irradiated at 5 K by 0.7 to 2.0 MeV electrons. Damage was monitored by electrical resistance measurements taken at 4.2 K From a comparison of energy-dependent damage rate measurements with electron displacement cross section curves based on the calculations of O. S. Oen, a threshold displacement energy of 22 ± 2 eV was found.

ISSN:0033-7579    

DOI:10.1080/00337577508239473

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

In this article, we calculate the cross section for atomic displacement as a function of proton penetration into Type 316 stainless steel. The cross section at a given penetration is reduced from that used in our past work. This is the result of new information on proton range, modification of the cross section calculations, and adoption of a higher displacement threshold energy. Swelling, void size, and void density data we have previously published are plotted against recalculated displacement damage. In general, the data are merely shifted to lower damage levels, and only one conclusion drawn in a previous publication appears to need modification. We also include a short discussion on the effect of voids on proton energy and displacement cross section as a function of proton penetration.

ISSN:0033-7579    

DOI:10.1080/00337577508239474

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

40 keV Ne, A, Kr and Xe ions have been used to bombard Ge single crystals at perpendicular incidence to (110) under clean target conditions. The temperature, dose and dose rate dependences of the accumulation of disorder have been determined. In a low temperature interval, 50–150°C, small temperature and dose rate effects on the accumulation of disorder were detected for Ne and A but for the other ions there was no such dependence. At temperatures above 150°C the temperature and dose rate for all types of ions used influence the accumulation of disorder. Different temperatures for the transition from a crystalline to a disordered region were detected for the various dose rates and ions used. Activation energies of 1.45 ± 0.15 eV for the observed defects have been calculated.

ISSN:0033-7579    

DOI:10.1080/00337577508239475

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Ge (110) single crystals heated to a temperature of 228°C have been bombardment disordered by 40 keV ions at a dose rate of 6 × 1011ions/cm2sec. The enhanced annealing caused by 40 keV Ge ions at a dose rate of 6 × 1011ions/cm2sec was studied as a function of dose by measuring the secondary electron yield. The depth distribution of damage was determined by the channeling technique using 500 keV He ions. It is shown that enhanced annealing occurs at the inner part of the damage region and proceeds outwards towards the crystal surface. The dose necessary to completely anneal a disordered layer is about 3.0 × 1015ions/cm2. A model for the annealing process is discussed. The maximum path length of the secondary electrons emitted from Ge during the bombardment with 40 keV Ge ions has been determined to be equal to approximately 40 A.

ISSN:0033-7579    

DOI:10.1080/00337577508239476

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Single crystals of Ge (110) were bombarded by 40 keV Ge ions at a dose rate of 6.0 × 1013ions/cm2sec in the temperature region 50–500°C. The secondary electron emission yield was used to study the state of disorder. In accordance with Chadderton's damage center nucleation model the growth of disorder can be divided into several dose intervals. Radiation enhanced and thermal annealing characteristics have also been studied using a probe ion beam of dose rate 6.0 × 1011ions/cm2sec. Evidence for both bombardment enhanced and thermal annealing are established. The bombardment enhanced annealing of a continuous disordered layer occurs at the inner region of the layer. The temperature dependence of the bombardment enhanced annealing indicates that a thermal step is included in the annealing process.

ISSN:0033-7579    

DOI:10.1080/00337577508239477

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A simple technique for the study of the spatial distribution of the damage produced by ion implantation of silicon has been developed. The damage depth distribution for 40 keV boron ions in silicon has been studied at irradiation doses from 7 × 1011to 3.9 × 1014ions/cm2and the relative defect peak depthRd/Rp= 0.85 determined. An increase of layer conductivity as the surface part of the implanted layer is removed has been revealed. This effect is caused by the presence of radiation defects in the surface region of the layer. The “electrical” cluster diameter is about 28 A and the overlapping cluster dose is close to 1 × 1013ions/cm2.

ISSN:0033-7579    

DOI:10.1080/00337577508239478

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Much research has been devoted to the understanding of the channeling of high-energy ions in crystals. This communication presents a preliminary experimental result on the ion chnnelling along thec−axis ([0001] axis] of pyrolytic graphite by the use of wide-angle Rutherford scattering.

ISSN:0033-7579    

DOI:10.1080/00337577508239479

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor