Grain boundary and surface segregation of Bi in Cu were investigated under identical conditions. Cu bicrystals containing deliberately made internal cavities at the interfaces were doped with Bi, annealed at different temperatures, and broken in an Auger microprobe. The segregation level at the free surfaces was found to be higher than that at grain boundaries. Grain-boundary and surface segreg...

Nanostructured materials are not immune from surface segregation, as can be shown for solid samples made from nanosized BaFelz.2xCoxTix019 barium femte 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, w...

Context. The observed presence of pure CO2 ice in protostellar envelopes, revealed by a double peaked 15 μm band, is often attributed to thermally induced ice segregation. The temperature required for segregation is however unknown because of lack of quantitative experimental data and this has prevented the use of ice segregation as a temperature probe. In addition, quantitative segregation stu...

We propose a new kinetic model for surface segregation during vapor phase growth that takes into account multiple mechanisms for segregation, including mechanisms for inter-layer exchange and surface diffusion. The resulting behavior of the segregation length shows temperature and velocity dependence, both of which have been observed in experiments. We compare our analytic model to experimental...

Surface segregation in wide band-gap nitride alloys was studied using ab initio calculations. In agreement with recent experiments we find that AlxGa12xN $0001% surfaces prefer Ga termination, and GaxIn12xN and AlxIn12xN $0001% prefer In termination. The segregation energy is found to depend critically on the type of surface reconstruction. For cation-terminated reconstructions on both the ~000...