Raman/Cr3+ fluorescence mapping of a melt-grown Al2O3/GdAlO3 eutectic

The paper reports on the Raman/fluorescence study of a melt-grown Al2O3/GdAlO3 eutectic composite. Raman bands from the α-alumina and gadolinium perovskite phases identified by X-ray diffraction were systematically observed together in the optically visible domains, 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.