Raman imaging and principal component analysis-based data processing on uranium oxide ceramics

Abstract

A ceramic sample of uranium dioxide is probed by Raman imaging followed by a combined Lorentzian fitting – Principal Component Analysis process. This allows to evidence structural or chemical inhomogeneities of the material, which affect Raman line intensities but also line positions, evidencing local symmetry lowering. The inhomogeneities were observed not only between grain cores and boundaries, but also inside grain cores themselves. Only a part of these intensity inhomogeneities is as expected due to different orientations of the ceramic grains. Besides, a zone noticeably differing from others has been distinguished, presumably due to local strains or to chemical nature (oxygen stoichiometry), showing the sensitivity of the analysis. This underlines the importance to perform Raman analysis in such ceramic materials at least on several points and better, in imaging mode.