摘要:

When the atoms of simple metals condense from the gas phase to give a solid, the valence electron wavefunctions are strongly modified by their overlap. At first sight this strong overlap might be expected to produce a complex situation, difficult to treat quantitatively. Yet the simple metals are perhaps the best understood of all solids and the reason is that the electron wavefunctions are plane-wave-like to a first approximation and deviations can be treated by perturbation theory.

ISSN:0033-7579    

DOI:10.1080/00337578008207107

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The energies of formation and migration of various rare gas-point defect complexes in an f.c.c. nickel lattice have been calculated for He, Ne, Ar, Kr, and Xe. Formation energies of rare gas atoms at interstitial sites are compared with those in substitutional sites. Binding energies are presented for self-interstitials and vacancies trapped to the various rare gas substitutionals. We also present migration energies and migration paths for various rare gas interstitials and substitutionals with and without trapped vacancies and self-interstitials. The migration energies are compared with the breakup energies for the corresponding complexes. We find that divacancy-rare gas complexes are rather stable and will migrate at relatively low energies compared to other substitutional rare gas migration processes.

ISSN:0033-7579    

DOI:10.1080/00337578008207108

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The different roles played by the valencesanddelectrons in determining the bulk properties of pure transition metals is described. In the light of this the expected behaviour of the inert gas-metal and metal-metal interatomic potentials is discussed.

ISSN:0033-7579    

DOI:10.1080/00337578008207109

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

This contribution aims to summarize the present theoretical methods used in treating gas migration in UO2, and to review briefly the extent to which predictions of such theories for the case of Xe in UO2, are compatible with experiment. The theory has two components: first the statistical mechanical treatment of gas trapping and migration; and secondly the calculation by computational methods of those energy terms which are shown by the statistical mechanics to be significant. The applicability of the results to the analysis of the experimental data depends upon certain crucial assumptions concerning the extent of thermodynamic control of the system. These problems will be described after our account of the theory which we present in the next section.

ISSN:0033-7579    

DOI:10.1080/00337578008207110

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

This paper reviews the basic theoretical description of the solubility and diffusion of rare gas atoms in crystalline solids. It then shows how this description can be used in conjunction with atomistic calculations to understand experimental observations. This understanding is particularly good for ionic compounds and a brief summary of the present situation is given for three main classes, namely those with the rocksalt structure, the fluorite structure and the caesium chloride structure.

ISSN:0033-7579    

DOI:10.1080/00337578008207111

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Most diffusion phenomena in solids can be understood (or sometimes misunderstood) on a purely classical model. For light interstitials (hydrogen isotopes, the positive muon, and potentially He) there may be anomalous temperature dependences, isotope effects and in the response to electric fields and temperature gradients. Some of these anomalies are quantal in origin, and will be discussed.

ISSN:0033-7579    

DOI:10.1080/00337578008207112

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The title of this symposium and proceedings, and of the other papers presented, reveals not only the general interest in the behaviour of rare gases in solids but some of the technological reasons why knowledge of such behaviour is important. Clearly basic information is required to understand fission gas generation and its consequence for swelling and embrittlement in fission reactors, for understanding and controlling first wall problems in fusion reactors and for attempting to design storage for active gas waste. In all of these areas the rare gas atoms are generated with kinetic energy and may thus interact differently, during their slowing down, with the solid than if they had been introduced more gently (e.g. via diffusion) into the solid. An important method of simulating the behaviour of such energetic rare gas atoms in solids is via external irradiation of the solid with rare gas ions of appropriate species and energies and it is the purpose of this review to evaluate studies of this nature.

ISSN:0033-7579    

DOI:10.1080/00337578008207113

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Cavity (void) formation and swelling in non-fissile materials during neutron irradiation and charged particle bombardments are reviewed. Helium is the most important inert gas and is primarily active as a cavity nucleant. It also enhances formation of dislocation structure. Preimplantation of helium overstimulates cavity nucleation and gives a different temperature response of swelling than when helium is coimplanted during the damage process. Helium affects, and is affected by, radiation-induced phase instability. Many of these effects are explainable in terms of cavity nucleation on submicroscopic critical size gas bubbles, and on the influence of the neutral sink strength of such bubbles. Titanium and zirconium resist cavity formation when vacancy loops are present.

ISSN:0033-7579    

DOI:10.1080/00337578008207114

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Transmission electron microscopy is used to investigate the spatial arrangement of the small gas bubbles produced in several fcc metals by 30 keV helium ion irradiation to high dose at 300 K. In what is a new result for this important class of metals it is found that the helium gas bubbles lie on a superlattice having an fcc structure with principal axes aligned with those of the metal matrix. The bubble lattice constantal, is measured for a helium fluence just below the critical dose for radiation blistering of the metal surface (∼4 ± 1017He/cm2). Implantation rates are typically ∼ 1014He ions cm−2sec−1. The values ofalobtained for copper, nickel and stainless steel are (7.6 ± 0.3) nm, (6.6 ± 0.5) nm and (6.4 ± 0.5) nm respectively. Above the critical dose the bubble lattice is seen to survive in some blister caps as well as in the region between blisters. Bubble alignment is also observed in the case of hydrogen bubbles produced in copper by low energy proton irradiation to high fluence at 300 K. The presentation of this data was accompanied by a cine film illustrating the behaviour of the gas bubble lattice in copper during post-irradiation annealing in the electron microscope. A summary of the film is given in the appendix.

ISSN:0033-7579    

DOI:10.1080/00337578008207115

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A brief survey is presented of mechanisms by which irradiation induced gas bubbles may grow and it concentrates on those processes, not directly dependent on continuing irradiation, which can cause rapid growth, including the situations where the gas pressure may exceed, be equal to, or be less than the surface energy restraint.

ISSN:0033-7579    

DOI:10.1080/00337578008207116

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor