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  • 11
    Electronic Resource
    Electronic Resource
    XPS study of irradiated polycrystalline TiO2 (1986)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 9 (1986), S. 248-248 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740090412
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  • 12
    Electronic Resource
    Electronic Resource
    Chemical changes in titanate surfaces induced by Ar+ ion bombardment (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 19 (1992), S. 286-290 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The reduction effects and compositional changes induced by 3.5 keV Ar+ bombardment of several titanates (i.e. SrTiO3, Al2TiO5 and NiTiO3) have been quantitatively investigated by XPS.In all the samples studied here the original Ti4+ species were reduced to lower oxidation states (i.e. Ti3+ and Ti2+), although to a lesser extent than in pure TiO2. On the contrary, whereas Sr2+ and Al3+ seem to remain unaffected by Ar+ bombardment, in agreement with the behaviour of the respective oxides (i.e. SrO and Al2O3), Ni2+ appears more easily reducible to Ni0 in NiTiO3 than in NiO. In addition, other specific differences were observed between the titanates, which reveal the existence of interesting chemical effects related to the presence of the different counter-ions in the titanates.In the case of Al2TiO5, its Ar+-induced decomposition to form TiO2 + Al2O3 could be followed by XPS.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740190154
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  • 13
    Electronic Resource
    Electronic Resource
    Use of XPS and Ar+ depth profiling to determine the dispersion degree of Ni in Ni/TiO2 and Ni/SiO2 catalysts (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 19 (1992), S. 508-512 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Two series of Ni/TiO2 and Ni/SiO2 catalysts prepared by different methods have been characterized by XPS and Ar+ sputtering. Depth profiles have been obtained from the intensity of the Ni 2p photoelectron peaks as a function of the sputtering time. The analysis has been carried out for samples in their precursor, calcined and reduced states, in order to obtain information on the changes in dispersion of the active phase through the whole activation process. In the case of reduced Ni/SiO2 catalysts, comparison with results by other techniques (i.e. H2 chemisorption, x-ray diffraction and transmission electron microscopy) has shown that the sputtering method may give a semi-quantitative assessment on the dispersion degree of nickel. However, for Ni/TiO2 catalysts in the SMSI state after reduction in H2 at 773 K only the Ar+ sputtering method was able to provide information on the distribution of nickel. In this case the depth profiles were consistent with partial solution of the nickel in the TiO2 matrix.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740190194
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  • 14
    Electronic Resource
    Electronic Resource
    Use of XAS and chemical probes to study the structural damage induced in oxide ceramics by bombardment with low-energy ionsPaper presented at ECASIA 93, Catania, Sicily, 4-8 October 1993. (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 418-424 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A preliminary study by x-ray absorption spectroscopy (XAS) of the structural modifications induced in mixed oxides by low-energy (1-5 keV) Ar+ bombardment is presented in this paper. The analysis of the extended x-ray adsorption fine structure (EXAFS) and x-ray adsorption near-edge structure (XANES) spectra recorded for bombarded Al2TiO5 and BaTiO3 has shown the randomization of the atomic network and the formation of TiO2 in the outermost layers of these materials. On the other hand, SO2 is proposed as a probe molecule to asess semiquantitatively the extent of structural damage in the surface layers of bombarded oxides. The incorporation of sulphur into this zone has been proved by depth profiling with XPS and Ar+ ions of 0.5 keV. In BaTiO3 the incorporation of sulphur increases with the energy of the primary ions. This fact suggests that the concentration of defects increases with the energy of the Ar+ beam and that the most disordered surface layers are more reactive towards SO2. A similar effect is not observed with TiO2 and Al2TiO5 because in these materials, where a considerable reduction of titanium to Tin+ (n 〈 4) species is produced by the preferential removal of oxygen, an overlay of elemental sulphur is formed by the reaction of SO2 with these species. This overlay prevents the diffusion of SO2 and therefore the incorporation of sulphur into the damaged layer of those samples.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740210617
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  • 15
    Electronic Resource
    Electronic Resource
    Charging and mixing effects during the XPS analysis of mixtures of oxides (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 111-114 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In this article we present an XPS analysis of mixtures of Al2O3 and TiO2 powders of different relative size in order to study differential charging effects. To illustrate some of the possible situations we have studied the behaviour of three different samples: (1) very large (microns) and porous particles of Al2O3 supporting TiO2 particles of relatively small size (300 Å); (2) Al2O3 and TiO2 particles of similar size (300 Å); and (3) very small particles (20-30 Å) of TiO2 dispersed in Al2O3 particles of 300 Å. The observed effects are then analysed by using Auger parameters and relative binding energies and discussed in terms of the different morphologies of the samples, as determined by TEM. The influence on charging of an electron flood gun and of Ar+ sputtering is also presented. In addition, ion-induced mixing effects have been clearly observed in the case of very small particles of TiO2 dispersed on alumina.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740220127
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  • 16
    Electronic Resource
    Electronic Resource
    Quantitative chemical depth profiles of ZrN/BN multilayers Dedicated to Professor Siegfried Hofmann on the occasion of his 60th birthday. (1998)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 806-814 
    Details
    ISSN: 0142-2421
    Keywords: multilayers ; ZrN ; BN ; AES ; RBS ; depth profiling ; factor analysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Multilayers of ZrN/BN have been deposited on Si(100) using a double ion beam sputtering system. The multilayers have been characterized by transmission electron microscopy, Rutherford backscattering spectroscopy and Auger electron spectroscopy (AES) depth profiles in order to get a quantitative analysis of the components and contaminants in the different layers and at their respective interfaces. Factor analysis is used to deconvolute the different chemical states of the components and to identify secondary phases and compounds that determine the quality of the multilayer. Two secondary phases have been observed at the different interfaces: one is associated with the incorporation of oxygen, mainly in the zirconium layer, and leads to the formation of ZrNxOy. In addition we have observed that Ar bombardment during the AES depth profile leads to the formation of ZrBxNy in all the interfaces. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Size and support effects in the photoelectron spectra of small TiO2 particles (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 392-396 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Three different TiO2 samples in the form of bulk material, colloidal particles and small clusters supported on SiO2 have been studied by extended x-ray adsorption fine structure (EXAFS), UV-visible, transmission electron microscopy (TEM) and XPS. The different values of the Ti 2p binding energies and the Auger parameter of Ti found for each sample show that the photoemission processes in these oxide materials are influenced by size and support effects. A difference in the relaxation energy of -1.1 eV is found for the TiO2/SiO2 sample with respect to TiO2, which is attributed to an effect of the silica support.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740180604
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  • 18
    Electronic Resource
    Electronic Resource
    Substrate Effects and Chemical State Plots for the XPS Analysis of Supported TiO2 Catalysts (1997)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 25 (1997), S. 292-294 
    Details
    ISSN: 0142-2421
    Keywords: XPS ; Auger parameter ; TiO2 ; catalyst ; chemical state plot ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The analysis by XPS of TiO2 deposited on different substrates (SiO2, MgO, Ag, SnO) shows the existence of shifts in the Ti 2p binding energy and Auger parameter values. The magnitude of these shifts is a function of the support and of the coverage. A systematic representation of these shifts is possible with a chemical state plot. The implications of the existence of such shifts for the characterization of catalysts are discussed. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Photoelectron spectroscopy versus absorption spectroscopy for quantitative characterization of nanometric powders coated with an overlayer (1998)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 1016-1026 
    Details
    ISSN: 0142-2421
    Keywords: XPS analysis ; nanoparticles ; XAS ; EELS ; quantitative characterization of powders ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: For the present study we have considered powders made up of small particles (〈1 μm) coated with a uniform overlayer. Different models have been developed to predict the elemental compositions in this kind of sample by x-ray photoelectron spectroscopy (XPS) and absorption spectroscopies: electron energy-loss spectroscopy (EELS) and x-ray absorption spectroscopy (XAS). Isolated spherical or cubic particles, aggregated spherical particles and continuously layered models have been considered to take different possible textures of the samples into account. Theoretical curves have been compared to experimental data obtained for Al2O3/Al ultrafine powders made up of Al metal cores coated with an Al2O3 overlayer. The dependence of both photoelectron and absorption spectroscopy analysis on overlayer thickness and sample texture as a function of particle size is discussed. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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