Nanostructured materials are not immune from surface segregation, as can be shown for solid samples made from nanosized BaFe_(12-2x)Co_xTi_xO_(19) barium ferrite particles and a variety of free clusters. Both theory and experiment provide ample demonstration that very limited dimensions of very small clusters does not necessarily impart stability against surface and grain boundary segregation. In fact, with the larger surface to volume ratio in small clusters and lower average atomic coordination, we anticipate that compositional instabilities in small clusters will readily occur.
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