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Hydrogen interstitial

Point defects and complexes exliibit metastability when more than one configuration can be realized in a given charge state. For example, neutral interstitial hydrogen is metastable in many semiconductors one configuration has H at a relaxed bond-centred site, bound to the crystal, and the other has H atomic-like at the tetrahedral interstitial site. [Pg.2885]

Color Changes in Quartz. AH quart2 contains small amounts of substitutional Al, typically 0.01%, as well as similar amounts of interstitial hydrogen or alkah metal ions. When an Al " replaces a one positive charge is missing and electroneutraUty is maintained by or Na", etc. Irradiation ejects one of a pair of electrons on an O adjacent to an Al ... [Pg.223]

Nevertheless it does not change the principle of the mechanism proposed by Scholten and Konvalinka, i.e. the ability to act catalytically of only the superficial palladium centers released from the vicinity of the interstitial hydrogen. Bearing in mind the dynamic character of the equilibrium in a palladium-hydrogen system as a whole is to regard such centers as being mobile in the surface layer of the hydride. [Pg.259]

In the final chapter of this volume, Van de Walle reviews the theoretical information that is available on isolated, interstitial hydrogen and muonium in crystalline semiconductors. Given the limited direct experimental information available on isolated, interstitial hydrogen and the vital contributions that muonium studies have made in confronting this deficit, it is clear that theory is a particularly essential tool for progress on this topic. Van de Walle first reviews the principal calculational techniques... [Pg.28]

To make contact with atomic theories of the binding of interstitial hydrogen in silicon, and to extrapolate the solubility to lower temperatures, some thermodynamic analysis of these data is needed a convenient procedure is that of Johnson, etal. (1986). As we have seen in Section II. l,Eqs. (2) et seq., the equilibrium concentration of any interstitial species is determined by the concentration of possible sites for this species, the vibrational partition function for each occupied site, and the difference between the chemical potential p, of the hydrogen and the ground state energy E0 on this type of site. In equilibrium with external H2 gas, /x is accurately known from thermochemical tables for the latter. A convenient source is the... [Pg.292]

Fig. 28. A floating bond (a) before and (b) after interacting with an interstitial hydrogen. The reverse reaction would involve the release of the hydrogen from the Si—H bond into an interstitial site, with reformation of the floating bond (Pantelides 1987b). Fig. 28. A floating bond (a) before and (b) after interacting with an interstitial hydrogen. The reverse reaction would involve the release of the hydrogen from the Si—H bond into an interstitial site, with reformation of the floating bond (Pantelides 1987b).
One of the earliest studies was an MNDO-cluster treatment by Corbett et al. (1983) of the isolated interstitial hydrogen and the corresponding molecule. In this early study, the isolated H was found to be stable at the M-site in silicon. This is directly between two adjacent C-sites, where the C-site is directly between next-near-neighbor silicons. (We note that in these calculations, the C- and M-site energies are very similar.) It was not known at that time, however, that the BC site is the stable location for neutral isolated interstitial hydrogen (see Chapter 16). In the Corbett study, an H2 molecule was found to be stable (or at least, metastable) in the tetrahedral interstitial site when oriented along a (111) direction. The... [Pg.556]

There is now an extensive and rapidly growing theoretical literature on the nature of hydrogen or muonium defects in silicon and to some extent in other semiconductors (Van de Walle, 1991 DeLeo, 1991). Much of this has dealt with isolated hydrogen or muonium where the most frequent comparisons have been with the muon hyperfine parameters, at least qualitatively, and other features of the muonium centers that can be inferred from /rSR experiments. Isolated interstitial hydrogen or muonium is certainly one of the simplest point defects conceivable. Hence explaining the existence and properties of the two drastically different forms of muonium observed in silicon and several other semiconductors has been a particular challenge to current theoretical methods. [Pg.564]

Theory of Isolated Interstitial Hydrogen and Muonium in Crystalline Semiconductors... [Pg.600]

More recently, hydrogen storage has become important, and interstitial alloys formed by incorporation of hydrogen into metals are of considerable interest. Niobium is typical of these. This metal is able to incorporate interstitial hydrogen up to a limiting composition of approximately NbH0.i-... [Pg.147]

A few general remarks about a group of metal-hydrogen phases have been included in 3.8.4.1 where interstitial hydrogen solutions in metallic structures have been described. However, as previously observed, a number of intermediate phases are also formed in several systems. A short summary of these is shown in Table 5.2 where their formulae very often have only an indicative character and several structure types correspond to more or less extended solid solution ranges. [Pg.331]

We have shown that A) interstitial hydride formation is observed only with partial occupation of the available holes, B) occupation of the interstitial position in isolated polyhedra is not observed, and C) occupation of all the holes in a close-packed lattice cancels metal-metal interactions. Therefore, it seems that interstitial hydrogen can be tolerated only in a fraction of the total number of holes, and with the weakening of metal-metal interactions. This behavior indicates strong competition between metal-metal and metal-hydrogen bonds, which is unique for hydrogen because interstitial carbon can stabilize some unusual arrangements in carbonyl carbide clusters (29, 30). [Pg.13]

The insulator effect on metal-metal bonding for the interstitial hydrogen atom in an octahedral hole can be extended readily to other geometries. Table V shows that a similar effect is expected in a tetrahedral hole. [Pg.15]

This bond-length expansion attributed to the interstitial hydrogen is between the half of the monohydrido trianion containing the interstitial hydrogen (w/H) and the other unoccupied half (wo/H). [Pg.107]

Table II. Mean Distances 1 (A) Involving the Interstitial Hydrogen Atoms Determined from Neutron Diffraction Studies of Compounds 3 and 4... Table II. Mean Distances 1 (A) Involving the Interstitial Hydrogen Atoms Determined from Neutron Diffraction Studies of Compounds 3 and 4...

See other pages where Hydrogen interstitial is mentioned: [Pg.165]    [Pg.303]    [Pg.23]    [Pg.28]    [Pg.71]    [Pg.140]    [Pg.223]    [Pg.293]    [Pg.367]    [Pg.446]    [Pg.448]    [Pg.527]    [Pg.554]    [Pg.557]    [Pg.563]    [Pg.578]    [Pg.596]    [Pg.636]    [Pg.411]    [Pg.51]    [Pg.15]    [Pg.50]    [Pg.425]    [Pg.16]    [Pg.100]    [Pg.101]    [Pg.102]    [Pg.104]    [Pg.107]    [Pg.108]    [Pg.109]    [Pg.111]   
See also in sourсe #XX -- [ Pg.56 , Pg.427 , Pg.429 , Pg.430 , Pg.431 , Pg.432 , Pg.435 , Pg.440 , Pg.585 ]

See also in sourсe #XX -- [ Pg.56 , Pg.427 , Pg.429 , Pg.430 , Pg.431 , Pg.432 , Pg.435 , Pg.440 , Pg.585 ]




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Diffraction interstitial hydrogen atom

Hydrogen interstitials

Hydrogen storage interstitial hydride

Hydrogen tetrahedral interstitial sites

Interstitial hydrogen atoms

Systems with an Interstitial Hydrogen Atom

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