The growth and structure of titanium dioxide films on a Re(10−10) surface: Rutile(011)-(2×1)

Rosenthal, Dirk; Zizak, Ivo; Darowski, N.; Магкоев, Т. Т.; Christmann, K.

doi:10.1016/j.susc.2006.04.017

Cited by 13 publications

(21 citation statements)

References 42 publications

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“…the second lowest after the (110) surface with 71 meVÅ -2 [10]. The rutile TiO 2 (101) surface in grown films and single crystals also possess a (1x2) reconstruction [34,35]. In analogy to a model for this rutile TiO 2 (101)-(1x2) surface [35,36] {110} and {100} facets.…”

Section: Ruo 2 As Bulk Phasementioning

confidence: 96%

On the CO-Oxidation over Oxygenated Ruthenium

Rosenthal¹,

Girgsdies

Timpe

et al. 2009

Zeitschrift Für Physikalische Chemie

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The oxidation of carbon monoxide over polycrystalline ruthenium dioxide (RuO 2 ) powder was studied in a packed-bed reactor and by bulk and surface analytical methods. Activity data were correlated with bulk phases in an in-situ X-ray diffraction (XRD) setup at atmospheric pressure. Ruthenium dioxide was pre-calcined in pure oxygen at 1073 K. At this stage RuO 2 is completely inactive in the oxidation of CO. After a long induction period in the feed at 503 K RuO 2 becomes active with 100% conversion, while in-situ XRD reveals no changes in the RuO 2 diffraction pattern. At this stage selective roughening of apical RuO 2 facets was observed by scanning electron microscopy (SEM). Seldom also single lateral facets are roughened. EDX indicated higher oxygen content in the following order: flat lateral facets > rough lateral facets > rough apical facets. Further, experiments in the packed bed reactor indicated oscillations in the CO 2 formation rate. At even higher temperatures in reducing feed (533-543 K) the sample reduces to ruthenium metal according to XRD. The reduced particles exhibiting lower ignition temperature are very rough with cracks and deep star-shaped holes. An Arrhenius plot of the CO 2 formation rate below the ignition temperature reveals the reduced samples to be significantly more active based on mass unit and shows lower apparent activation energy than the activated oxidized sample. Micro-spot X-ray photoelectron spectroscopy (XPS) and XPS microscopy experiments were carried out on a Ru(0001) single crystal exposed to oxygen at different temperature. Although low energy electron diffraction (LEED) images show a strong 1x1 pattern, the XPS data indicated a wide lateral inhomogeneity with different degree of oxygen dissolved in the subsurface layers. All these and the literature data are discussed in the context of different active states and transport issues, and the metastable nature of a phase mixture under conditions of high catalytic activity.

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Section: Ruo 2 As Bulk Phasementioning

confidence: 96%

On the CO-Oxidation over Oxygenated Ruthenium

Rosenthal¹,

Girgsdies

Timpe

et al. 2009

Zeitschrift Für Physikalische Chemie

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“…Films have the invaluable advantage that they can be prepared in a very clean and electrically conductive fashion and, in addition, be grown by epitaxy in a certain desired crystallographic orientation forced by the lattice parameters of the host surface. In the recent literature there are some detailed reports on the growth and structure of thin titanium dioxide films grown on Ni, Pt, Mo, W, Ru and Re surfaces, [16,17,41,[63][64][65][66][67][68][69][70][71][72][73][74] which we consider in somewhat more detail below. Surface-analytical methods employed were, among others, LEED, Auger electron spectroscopy (AES), ion scattering, X-ray photoelectron spectroscopy (XPS), STM, surface X-ray diffraction and photoemission.…”

Section: (110) Oriented Rutile Thin Filmsmentioning

confidence: 99%

“…Red spheres denote oxygen and white titanium. After Rosenthal et al [41] Reproduced with permission. Figure 2.…”

Section: (110) Oriented Rutile Thin Filmsmentioning

confidence: 99%

“…In one case only, TiO 2 surfaces have been prepared in the form of epitactic thin films with (011) orientation (see Section 2.1.3). [41] Titanium Dioxide on Nickel: Ashworth and Thornton [64] grew thin (~4 ML) titania films on a Ni(110) surface by means of Ti evaporation and subsequent oxidation in a flow of oxygen of 1 10 À7 mbar at 800 K. The film thickness was controlled by…”

Section: (110) Oriented Rutile Thin Filmsmentioning

confidence: 99%

“…The well-known rutile structure is tetragonal, the unit cell (AB 2 type) contains two TiO 2 units, each Ti 4 + ion is coordinated by six oxygen O 2À ions in a slightly distorted octahedron and each O 2À ion is surrounded by three Ti 4 + ions forming an almost equilateral triangle. [40] A ball model taken from previously published work [41] displays the two most abundant surface orientations (110) and (011) and is presented in Figure 1. All following considerations refer to the rutile modification, unless otherwise stated.…”

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confidence: 99%

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Model Studies on CO Oxidation Catalyst Systems: Titania and Gold Nanoparticles

et al. 2010

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The peculiar catalytic activity of Au-supported titanium dioxide surfaces in the CO oxidation reaction has been a focus of interest for more than twenty years. Herein, recent data concerning preparation and structural characterisation of planar catalyst model systems consisting of single-crystalline titania and/or gold nanoparticles deposited thereon is presented and reviewed. We first expand on the deposition and growth of TiO(2) films on selected metal host surfaces and then consider the deposition of Au nanoparticles on these surfaces, including information on their geometric and electronic structures. The second issue is the interaction of these materials with carbon monoxide (one of the essential ingredients of the CO oxidation reaction) which serves as a probe molecule and monitor of the chemical activity of the model catalyst samples. Concerted efforts relating the structural and chemical properties of the respective binary materials (titania support plus deposited gold) can help to tackle and finally resolve the still open problems concerning the high activity of Au-TiO(2) catalysts in the CO oxidation reaction.

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Free vibration of symmetric planar frames via the force method and canonical forms

Kaveh

Arvanaq

2011

Numer Methods Biomed Eng

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SUMMARYIn this paper, the method recently developed for the free vibration of symmetric frames using canonical forms of stiffness matrices is extended to the flexibility matrices. Weighted graphs are associated with the flexibility and mass matrices of the frame structures. Using graph symmetry, the models are decomposed into submodels and a healing process is employed, such that the union of the eigenvalue of the matrices corresponding to the healed submodels contains the eigenvalues of the entire model. This two-step process is termed as the factorization of a weighted graph. The presented method is illustrated through simple examples having different symmetries.

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The growth and structure of titanium dioxide films on a Re(10−10) surface: Rutile(011)-(2×1)

Cited by 13 publications

References 42 publications

On the CO-Oxidation over Oxygenated Ruthenium

On the CO-Oxidation over Oxygenated Ruthenium

Model Studies on CO Oxidation Catalyst Systems: Titania and Gold Nanoparticles

Free vibration of symmetric planar frames via the force method and canonical forms

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