The evolution of the passivating layer (during the first reduction/reoxidation cycle, in function of the number of reduction/reoxidation cycles and with the storage of the electrode in the electrolyte) formed at the surface of a lithiated carbon electrode in LiCF3SO3/carbonates mixture electrolyte has been followed by using 1 MeV 4He+ induced Rutherford Backscattering Spectrometry (RBS). Two RBS simulation codes "RUMP" and "PERM" , whose approaches are different, have been applied to the treatment of the RBS data and have allowed to obtain informations about the structure (thickness and atomic elemental composition) of the passivating layer. These two codes provide similar results. The passivating layer has a thickness in the range 20-30 nm. Its structure appears to be complex with the presence of two different sublayers respectively composed of the reduction products of the salt in the inner sublayer (with the main presence of fluorine and sulphur indicating the possible existence of LiF and Li2S) and reduction products of the solvents in the outer sublayer (with a high concentration in oxygen indicating the presence of Li2CO3 and RCO3Li where R is an alkyl radical).

The aqueous corrosion behavior of lanthanide aluminosilicate glasses has been studied under static conditions (T=96°C, duration=1 and 3 months, glass surface area/leachate volume, S/V=0.3 cm−1) by means of solution and solid analyses. It was found that these glasses exhibit a high chemical durability. The influence of yttrium, magnesium and nitrogen, which are supposed to improve the mechanical properties, on the chemical durability, has been investigated. After a one-month experiment, lanthanum and yttrium releases were found to be about 10−7 mol l−1, while silicon and aluminum releases were about 10−5 mol l−1. Yttrium seems to improve the chemical durability. The presence of nitrogen does not seem to modify the glass constituents releases, but seems to improve the surface state of the altered glass. XPS experiments reveal that lanthanum and yttrium are more concentrated near the surface (20–30 Å) of the glass after the leaching test.

Contributors Preface Part I Topological Models for the Crystalline and Amorphous Phases (a) Description of the Atomic Arrangement in SiO-2 Polymorphs Chapter 1 The Topology of Silica Networks (by L. W. Hobbs, C. E. Jesurum and B. Berger) Chapter 2 Low-Pressure Crystalline Phases of SiO-2 (by G. Dolino) Chapter 3 Theoretical Investigations of the Structure of Amorphous SiO-2 at Elevated Pressure (by L. Stixrude) (b) Experimental Analysis of SiO-2 Atomic Networks Chapter 4 Nuclear Magnetic Resonance as a Structural Probe of SiO-2 (by R. Dupree) Chapter 5 Neutron and X-Ray Scattering Studies of Vitreous Silica (by A. C. Wright and R. N. Sinclair) Part II Electronic Structure of the Si-O-2 Bond and the Extended Network (a) Calculations and Modelling of the Electronic Structure Chapter 6 Molecules as a Basis for Modeling the Force Field of Silica (by G. V. Gibbs, F. C. Hill, M. B. Boisen, Jr, and R. T. Downs) Chapter 7 First Principles Calculation of the Electronic Structures of Crystalline and Amorphous Forms of SiO-2 (by W. Y. Ching) Chapter 8 The Electronic Structure of Silica Using Ab Initio Pseudopotentials (by J. R. Chelikowsky and N. Binggeli) (b) Experimental Analysis of the Electronic Structure Chapter 9 X-Ray Absorption Near Edge Structures of SiO-2 (by F. Jollet) Chapter 10 Electron Energy Loss Structures of SiO-2 (by M. Gautier-Soyer) Part III Macroscopic and Point Defects Chapter 11 Theory of Electronic and Structural Properties of Point Defects in SiO-2 (by A. H. Edwards, W. B. Fowler and J. Robertson) Chapter 12 Radiation-Induced Defects and Electronic Modification (by P. Paillet, J. L. Leray and H. J. von Bardeleben) Chapter 13 Transient Defects and Electronic Excitation (by N. Itoh, A. M. Stoneham and K. Tanimura) Chapter 14 Radiation-Induced Defects and Structural Modifications (by E. Dooryhee, J.-P. Duraud and R. A. B. Devine) Part IV Processing and Applications of Crystalline and Amorphous Phases Chapter 15 Quartz Oscillators (by J. R. Vig) Chapter 16 Science and Technology of Silica Lightguides for Telecommunications (by C. R. Kurkjian and D. M. Krol) Chapter 17 Microstructure, Surface Chemistry, and Properties of Silica Gels (by C. J. Brinker, W. L. Warren and S. Wallace) Index

Proton-induced X-ray emission (PIXE) and light element analysis have been performed with the nuclear microprobe at the Laboratoire Pierre Süe (Saclay-France) in glass inclusions of the carbonaceous chondrites: Allende, Kaba and Renazzo, and in the achondrite meteorite: Chassigny. Carbon contents in olivine of chondrules are below the nuclear reactions analysis (NRA) detection limit, however, glasses from glass inclusions hosted by these grains, contain an appreciable and highly variable quantities of carbon (200–1600 ppm). This could indicate variable amounts of C trapped during glass inclusion formation. On the other hand, nitrogen is present in highly variable amounts in glasses of both, chondrites and achondrites minerals. Its abundance, correlated with depth from the section surface which suggests loss of N during analyses and therefore the possible existence of a very mobile (volatile?) species. A chondritic Rb/Sr and K/Rb ratio obtained by PIXE analyses in the glass-bearing inclusions of the Chassigny meteorite points towards a primitive source for the glass precursor of Chassigny inclusions.

Micro-PIXE and micro-Synchrotron X-ray fluorescence (SXRF) are powerful techniques dedicated to the study of trace elements in different matrices. However they do not give access to the chemical states of elements. By combining micro-X-Ray Absorption Near Edge Structure (XANES) and micro-SXRF using synchrotron radiation, the point analysis of an element and its proportion in different chemical states become possible. Moreover the shape and fine structures of the edge give information concerning its local structure (inter-atomic distances and coordination number). After a short presentation of both the experimental and the basic principles of μ-XANES, the study of iron oxidation states will be given to illustrate the case of geological samples. Such a study at a micrometer scale on coexisting minerals remains a fundamental goal in geochemistry. Particularly in glass inclusions trapped in volcanic minerals, this information enables one to infer the physical and chemical conditions which control the evolution of the magmas. A practical method of quantification has been employed and theoretical simulations are in development simultaneously. First results as well as the capabilities of the method are presented.

This study deals with the sputtering of uranium atoms from UO2 surfaces, induced by high 238U15+ and 116Sn36+ irradiation. The sputtered uranium atoms were collected on mica energy foils which were subsequently irradiated with thermal neutrons in order to fission the 235U. The fission fragments created latent tracks in mica which were revealed by chemical etching. Finally, we determined the track densities as a function of the emission angle in the mica detectors using three microscopy techniques: optical microscopy, SEM and AFM. The total yield of uranium emission and the angular distribution are given for both projectiles.

The kinetics of the growth of copper clusters on the alumina (0001) surface was studied as a function of surface structure, using EXAFS at the Cu K edge. Equivalent Cu coverages ranging from 0.5 to 4 equivalent monolayers were deposited in situ, at room temperature, on alumina (0001) surfaces exhibiting the (1×1) or the (31 x 31) reconstructed structure. The evolution of mean cluster size with deposition time was followed from the mean Cu coordination number in the clusters deduced from the EXAFS data. The increase of the mean cluster radius with deposition time is characteristic of a coalescence mechanism on both surfaces. The growth is quicker on the reconstructed surface, likely due to different surface diffusion properties of both surfaces.

Na and Ca diffusion was induced in glasses by intense microbeams of swift protons. By contrast with previous studies using macrobeams (semi-infinite geometry), the geometry of the interaction is cylindrical which offers new directions for diffusion. Furthermore, we explored the influence of high current densities. The main results show that Na migrates towards the surface in the irradiated zone, and is then spread around this region. The Ca signal variation is not interpreted as a diffusion process, but only as a reflection of the change in matrix density. The Na migration is shown to be driven by an electric field created in the irradiated cylindrical zone.

Nowadays, nuclear microprobes are commonly used in Earth Sciences as an analytical tool to detect a large number of trace elements in geological samples. However, radiation damages induced in natural glasses during an analysis by ionization are not completely controlled. Some difficulties remain in defining the appropriate analytical conditions without modifying the alkaline distribution in the matrix. Our approach consists of using a synthetic glass to quantify these modifications. With a 2 MeV proton microbeam, the Na and Ca signal evolution has been followed as a function of the deposited charge. Na and Ca distribution maps in and around the beam impact evidence a complex remobilization of both elements. The use of three different proton energies (1.32 MeV, 2 MeV and 3 MeV) permits the Na and Ca distribution profiles to be realized for increasing depth layers. A similar behavior of alkaline elements has been found within complex natural glasses.

We show that SEXAFS can be used to determine the growth law of subnanometric particles. In the case of copper deposited on alumina the dynamic scaling of the mean cluster size distribution, in the radius range 2-10 A, is demonstrated. This scaling is explained by the coalescence of copper clusters, as in breath figures due to the condensation of liquid droplets. This growth law can be fitted by a power law with an exponent 1.2 and is fairly well reproduced by a purely stochastic coalescence model.

We present a time resolved XAS study of the phase transition of tetragonal to orthorhombic lead monoxide PbOα → PbOβ, occuring at 490 °C. XAS experiments were carried out on a fast energy dispersive spectrometer and full Pb L3 XAS spectra were periodically recorded as a function of the sample temperature within the range 100–700 °C. The time resolution is about 1 s. XAS experiments give evidence for a dynamical two-step solid state transformation.The phase transition appears to be initiated by O atom displacements within the PbO4 structural pyramidal unit. Pb atom displacements seem to occur in a second stage of the phase transition.

The course of radiation induced damage produced in alpha-quartz by neutrons, ions, electrons or photons - commonly known as metamictization - has been re-analyzed by careful comparison of available experimental data. Specific interest was devoted to confront experimental metamict state features with current structural models. It comes out that the metamict state of irradiated quartz should exhibit some structural characteristics of the modulated structure proposed for vitreous silica. The metamictization process is consistent with a structural relaxation process of a highly defective quartz matrix. According to this new point defect analysis, structural relaxation should be triggered by a critical concentration of oxygen vacancy point defects likely to significantly lower the connectivity of the SiO2 network. Various experimental results are interpreted by incorporating the influence of the SiO2 crystalline polymorph and the influence of the nature of the irradiating particle to the point defect model.

We have studied the first stages of the growth of copper on two different α-Al2O3 (0001) alumina substrates, presenting respectively a (1 × 1) and a (√31 × √31)R ± 9° LEED (low energy electron diffraction) pattern. The study was realised by means of surface sensitive X-ray absorption spectroscopy (SEXAFS) at the CuK edge. For equal amounts of deposited copper (50% of an equivalent monolayer), we found quite different copper/alumina interfaces as a function of the substrate reconstruction. In the case of the (1 × 1) surface, we noticed the coexistence of copper dimers and very small copper nanoclusters (about 1 shell) weakly bonded to the substrate via the Al surface atoms. In the case of the (√31 × √31)R ± 9° reconstructed substrate, we detected slightly bigger Cu nanoclusters than those present on the (1 × 1) surface. We also observe that some Cu atoms are incorporated to the substrate, occupying the vacancies of the reconstructed surface. No CuO bonds are detected in both interfaces. This result can be understood in the case of the aluminium rich (√31 × √31)R ± 9° surface. However, it is more surprising in the case of the (1 × 1) surface and supports the hypothesis of an Al-terminated (1 × 1) alumina substrate.

Solid mineral surfaces generally present specific vibrational, electronic and atomic properties due to the loss of the bulk symmetry. Under certain circumstances, atomic reconstruction processes can occur. In polymers, the nature of the bonding and the long range organization of the macromolecules make it difficult to define the surface structure, although the recent developments of scanning tunnelling and atomic force microscopy enable one to visualize the surface arrangement. However, when irradiated with an ionizing radiation, the surface layer can be greatly modified, so as to produce a material completely different from the irradiated bulk, as a consequence of bond breaking, chain scissions and the ability to desorb atoms or molecules. The result is a radiation rebuilt surface whose electronic and atomic structures are quite specific, depending on the nature of the radiation and the deposited dose, and leading to original electrical or optical properties. This also enhances the chemical reactivity of the surface, which favours the formation of various interfaces: metal-polymer, polymer-polymer, etc. On the other hand, this radiation fragility must be taken into account in the course of surface analysis using ionizing radiation such as X-rays or energetic light ions.

We have studied the influence of the mean Ce-O distance on the Ce L(3) X-ray absorption spectra (XAS), for a given eight-fold oxygen coordination, like in CeO2 (cubic symmetry). For that purpose, solid solutions of cerium-doped Y2O3 (2 at% and 5 at%) were synthesised. The local atomic arrangement in the solid solutions, as deduced from the EXAFS (Extended X-ray Absorption Fine Structures) measurements, is well represented by a 8-fold oxygen coordination around the cerium atoms like in CeO2, with a Ce-O distance of 2.28 Angstrom as in Y2O3, shorter than in CeO2 (2.34 Angstrom). This shortening of the Ce-O distance increases the Madelung field acting on the electrons of the cerium atoms, and leads to an increase of the charge transfer energy between cerium and oxygen. This affects the shape of the Ce L(3) X-ray absorption spectrum of the solid solutions, compared to that of CeO2. The changes observed can be explained in the framework of the multielectronic configuration-mixing model.

Surface sensitive X-ray absorption spectroscopy at the Cu K edge has been used for studying the Cu/Al2O3 interface. We have prepared in situ both oxidised and reduced alpha-alumina substrates and have evaporated equal amounts of copper (approximate to 80% monolayer) on each. From the analysis of the data we can infer that: (a) The Cu/Al2O3 interface grows via the Volmer-Weber mode whatever the alpha-alumina surface oxidation state. (b) For equal amounts of copper, much larger clusters are found on the reduced alpha-Al2O3 than on the oxidised substrates.

Surface sensitive X-ray absorption spectroscopy has been used for investigating the differences in the environment of copper atoms at the Cu/Al2O3 interface for different oxidation states of the α-alumina substrate. We have prepared in situ both oxidised and reduced α-alumina surfaces and have evaporated equal amounts of copper (∼ 80% monolayer) on each. Under our experimental conditions, we infer that: (a) the interface grows via the Volmer-Weber mode rather than the Stranski-Krastanov mode suggested in the literature. (b) The morphology of supported Cu clusters depends strongly on the oxidation state of the alumina. For equal amounts of copper, much larger clusters are found on reduced Al2O3(0001) substrates than on oxidised substrates.

Reflection electron energy loss experiments were carried out on monocrystalline (101̄0) and (0001) quartz samples. Five bulk single loss structures appear at 10.5, 12.5, 14.3, 17.9 and 21.3 eV. The 10.5 eV peak is due to the SiO2 exciton, the 21.3 eV peak to the SiO2 plasmon, and the three other transitions are interband transitions, as confirmed by the calculated JDOS. Our experiments show that two electronic transitions at 5.1 and 7.2 eV appear in the gap of α-quartz under several excitations: by phonon excitation (UHV heating), by atomic excitation (collision between the 7 keV ions and the nuclei of the surface and near-surface atoms), and by electronic excitation (interaction with the 350 eV electron beam). The defects responsible for these structures are located at the surface and related to the neutral oxygen vacancy that is the precursor of the E$́centre.

Disorder induced by ion beam treatments (irradiation with energetic Au ions or Zr implantation) in the Y2O3 ceramic has been studied. By combining several experimental techniques, we obtained information on electronic distributions and on atomic rearrangements around each species of the matrix. Three types of defects have been investigated. They are the intrinsic defects: on the oxygen and Y sublattices, and an extrinsic defect: the implanted impurity, here Zr, a cation greedy of oxygen. No amorphisation was reached under the experimental beam conditions used here. The whole matrix remained well crystallized, despite the fact that the final disorder around the impurity, located on a substitutional site, was rather large. Oxygen desorption occurred on the ion beam treated depth. We found that (i) oxygen vacancies appeared to be ordered and (ii) there was a competition between energy deposition via atomic collisions which induced O desorption and chemical effects due to Zr implantation which retained O.