Structural study of SiO2TiO2 sol—gel films by X-ray absorption and photoemission spectroscopies

Orignac, Xavier; Vasconcelos, Helena Cristina; Almeida, Rui M.

doi:10.1016/s0022-3093(97)00155-5

Cited by 46 publications

(33 citation statements)

References 17 publications

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“…p* transition, and therefore, the lack of this feature demonstrates that no significant p-bonded oxygen, which would be expected for a double-bonded state, is present. These spectra have identical characteristics with those of amorphous SiO 2 found in the literature [17][18][19] and show no indication of crystalline Si-O bonding or oxides that deviate from the stoichiometry of SiO 2 [20]. NEXAFS spectra were also obtained at the carbon and fluorine edges (data not shown).…”

Section: µMsupporting

confidence: 78%

Characterization of Microscale Wear in a Polysilicon-Based MEMS Device Using AFM and PEEM–NEXAFS Spectromicroscopy

et al. 2009

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Mechanisms of microscale wear in siliconbased microelectromechanical systems (MEMS) are elucidated by studying a polysilicon nanotractor, a device specifically designed to conduct friction and wear tests under controlled conditions. Photoelectron emission microscopy (PEEM) was combined with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and atomic force microscopy (AFM) to quantitatively probe chemical changes and structural modification, respectively, in the wear track of the nanotractor. The ability of PEEM-NEXAFS to spatially map chemical variations in the nearsurface region of samples at high lateral spatial resolution is unparalleled and therefore ideally suited for this study. The results show that it is possible to detect microscopic chemical changes using PEEM-NEXAFS, specifically, oxidation at the sliding interface of a MEMS device. We observe that wear induces oxidation of the polysilicon at the immediate contact interface, and the spectra are consistent with those from amorphous SiO 2 . The oxidation is correlated with gouging and debris build-up in the wear track, as measured by AFM and scanning electron microscopy (SEM).Keywords Microscale wear Á Microelectromechanical systems (MEMS) Á Nanotractor Á Photoelectron emission microscopy (PEEM) Á Atomic force microscopy (AFM)

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Section: µMsupporting

confidence: 78%

Characterization of Microscale Wear in a Polysilicon-Based MEMS Device Using AFM and PEEM–NEXAFS Spectromicroscopy

et al. 2009

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“…Although ethanol can participate in esterification or alcoholysis in the sol-gel reactions [9], it is likely that the final structure of the films after heat treatment, at the atomic level, is not affected by the initial amount of ethanol. This was confirmed experimentally by comparing Si, Ti and O XPS peaks, as well as NEXAFS spectra of two samples with Re equal to 2 and 4 [14].…”

Section: Discussionsupporting

confidence: 64%

Influence of solvent concentration on the microstructure of SiO2−TiO2 sol-gel films

Orignac

Vasconcelos

et al. 1997

J Sol-Gel Sci Technol

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Abstract. Spin-coating is one of the possible methods for the fabrication of optical planar waveguides. These have several applications in integrated optical devices, provided that their optical losses are below ~1 dB/cm. The attenuation is caused in part by surface and bulk scattering. The latter depends on the microstructure of the films and, more particularly, the porosity, which is studied here. A series of SiO2-TiO2 films were prepared from solutions containing different concentrations of ethanol. The influence of the ethanol/(Si + Ti)alkoxides volume ratio on the porosity was investigated by Ellipsometry, Infrared Spectroscopy, and Scanning Electron Microscopy. The porosity volume fraction was found to reach a minimum when the ethanol volume ratio is near 4.

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“…This behavior is attributed to the shorter Ti-O-Ti and Ti-O-Si bonds with respect to the Si-O-Si bonds. 26,27 The sample 100Ti@CMS + TiNPs (trace F) shows an additional shoulder in the WAXS pattern at about 25 that is attributed to the (101) reflection of anatase (see also Fig. 3c, in which the contribution of the amorphous part is subtracted).…”

Section: Mesoporous Nanoparticle Characterizationmentioning

confidence: 96%

All-inorganic core–shell silica–titania mesoporous colloidal nanoparticles showing orthogonal functionality

et al. 2011

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Colloidal mesoporous silica (CMS) nanoparticles with a thin titania-enriched outer shell showing a spatially resolved functionality were synthesized by a delayed co-condensation approach. The titaniashell can serve as a selective nucleation site for the growth of nanocrystalline anatase clusters. These fully inorganic pure silica-core titania-enriched shell mesoporous nanoparticles show orthogonal functionality, demonstrated through the selective adsorption of a carboxylate-containing ruthenium N3-dye. UV-Vis and fluorescence spectroscopy indicate the strong interaction of the N3-dye with the titania-phase at the outer shell of the CMS nanoparticles. In particular, this interaction and thus the selective functionalization are greatly enhanced when anatase nanocrystallites are nucleated at the titania-enriched shell surface.

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Structural study of SiO2TiO2 sol—gel films by X-ray absorption and photoemission spectroscopies

Cited by 46 publications

References 17 publications

Characterization of Microscale Wear in a Polysilicon-Based MEMS Device Using AFM and PEEM–NEXAFS Spectromicroscopy

Characterization of Microscale Wear in a Polysilicon-Based MEMS Device Using AFM and PEEM–NEXAFS Spectromicroscopy

Influence of solvent concentration on the microstructure of SiO2−TiO2 sol-gel films

All-inorganic core–shell silica–titania mesoporous colloidal nanoparticles showing orthogonal functionality

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