Yttrium segregation and intergranular defects in alumina

International audienceIntergranular segregation of yttrium is investigated in a rhombohedral twin grain boundary of alumina. The deviation from the exact coincidence 7 is compensated by a periodic arrangement of intergranular dislocations. TEM tools (CTEM, EDXS, EFTEM and EELS/ELNES) have been used to characterize changes in chemical and electronic environments along this twin. Within the experimental limits, no Y is detected in the perfect twin parts. On the other hand, Y segregation occurs very locally in the dislocation cores on about four atomic planes perpendicularly to the GB which in fact corresponds to the step height associated with the interfacial dislocation. By comparison with an undoped bicrystal, both the dislocation distribution and the Y segregation localisation confirm the influence of Y on the dislocation mobility. Furthermore, in the Y-rich defects, high spatial resolution analysis of the energy loss near edge structures (ELNES) of the Al-L23 absorption edge brings some enlightenments about the Al3+ cation environment, provided the effects of local radiation damage are fully considered and under control

Relationship between serotypes, disease characteristics and 30-day mortality in adults with invasive pneumococcal disease

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