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Excess point defects created by irradiation in metallic alloys diffuse and annihilate at sinks available in the microstructure, such as grain boundaries, dislocations, or point defect clusters. Fluxes of defects create fluxes of alloying elements, leading to local changes of composition near the sinks and to a modification of the properties of the materials. The direction and the amplitude of this radiation-induced segregation, its tendency to produce an enrichment or a depletion of solute, depend on a set of transport coefficients that are very difficult to measure experimentally. The understanding of radiation-induced segregation phenomena has, however, made significant progress in recent years, thanks to the modeling at different scales of diffusion and segregation mechanisms. We review here these different advances and try to identify the key scientific issues that limit the development of predictive models, applicable to real alloys. The review addresses three main issues: the calculation of the transport coefficients from ab initio calculations, the modeling of segregation kinetics at static point defects sinks—mainly by kinetic Monte Carlo or diffusion-reaction models—and the more challenging task of modeling the dynamic interplay between radiation-induced segregation and sink microstructure evolution, especially when this evolution results from annihilation of point defects. From this overview of the current state-of-the-art in this field, we discuss still-open questions and guidelines for what constitutes, in our opinion, the desirable future works on this topic. [ABSTRACT FROM AUTHOR]

X-ray emission and absorption spectroscopy (XES and XAS, respectively) are important and powerful techniques for determining the electronic properties of materials. Both are used to study magnetic circular dichroism (MCD) which is especially useful for analyzing the magnetic properties of materials. We present XAS and XES measurements and a MCD model study of two thin film layered samples containing SmCo layers in order to report on the applicability of soft x-ray spectroscopic techniques to determine the composition, layer thickness, and electronic structure of such materials. Using a transmission by fluorescence attenuation (TFA) technique we determined the composition and thickness of the SmCo layer to be consistent with the intended composition and thickness. We also confirmed the thickness of the other layers by comparing the XES from the thin film with that of a bulk sample. We showed by a model study that TFA could be used to obtain MCD, and thus the anisotropy of the sample, for film thicknesses between about 400 and 800 Å. [ABSTRACT FROM AUTHOR]

First principles calculations of Zn11X1S12 supercells in the zincblende structure, where X is a magnetic ion, show that when X=Cr, Fe, and Ni the materials are calculated to be half metallic and ferromagnetic, i.e., the densities of states of these bulk materials at the Fermi energy is calculated to be 100% spin polarized and the exchange interaction is ferromagnetic. This behavior persists even when on-site Coulomb “Hubbard U” potentials are applied. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]