arXiv subjects

Gwénael Gouadec

Publications and source records attributed to Gwénael Gouadec.

3 recordsLinked to original sources

arXiv2007

Raman Spectroscopy of Nanostructures and Nanosized Materials

The interest of micro and tip-enhanced Raman spectroscopy to analyze nanosized and nanostructured materials, chiefly semiconductors, oxides and pristine or functionalized carbon nanotubes, is reviewed at the light of the contributions to this special issue. Particular attention is paid to the fact that chemical reactions, size or shape distribution, defects, strain and couplings may add to nano-dimensionality in defining the Raman signature.

cond-mat.mtrl-sci↗

arXiv2007

Non-Destructive Mechanical Characterization of Sic Fibers by Raman Spectroscopy

The paper provides a comprehensive study on Raman spectroscopy versatility as a fast and non destructive tool for the prediction of the mechanical properties of SiC fibers derived from a polymeric precursor (NLM, Hi, Hi-S, SA and Sylramic grades) or produced by CVD (SCS-6 fiber), including in situ analysis in CMCs or MMCs. We show how the results of very simple spectra fitting are correlated with Young's modulus, tensile strength and micro-hardness. The reason why such a correlation exists, the common dependency of Raman signal and mechanical behavior to the micro/nanostructure of ceramics, is discussed.

cond-mat.mtrl-sci↗

arXiv2007

Raman/Cr3+ Fluorescence Mapping of Melt-Grown Al2o3/Gdalo3 Eutectics

The paper reports on the Raman/fluorescence study of melt-grown Al2O3/GdAlO3 eutectic composites. Raman bands from the -alumina and gadolinium perovskite phases identified by X-ray diffraction were systematically observed together in the domains optically visible, even when the latter were much larger than the Raman probe. This suggests a more complex interlocking pattern than appearing on SEM or optical microscopy images. The polarization of alumina and GdAlO3 Raman bands evidenced the preferential orientation of Al2O3 phase with respect to the sample growth direction, in agreement with TEM results. In addition, the position of chromium impurity fluorescence bands was used to map the residual stress in alumina phase. It is a compression in the 200-300 MPa range.

cond-mat.mtrl-sci↗