This project aims at the study of the structure and materials transport properties of nanocrystalline materials. Diffusion is a determining feature of a number of application-oriented properties of nanocrystalline materials, such as enhanced ductility, diffusion-induced magnetic anisotropy, enhanced ionic mass transport, and improved catalytic activity. In order to gain insight into structure-property relationships, the diffusion studies are combined with a comprehensive structural characterization including the techniques of x-ray diffraction and positron annihilation. Positron lifetime spectroscopy has proven a versatile tool for the study of interfacial structural free volumes and lattice vacancies in nanocrystalline materials. Chemical sensitivity is achieved by making use of coincident Doppler broadening measurements of the positron-electron annihilation photons. With this background reduced Doppler broadening new potentials emerge for a chemical characterization of structural complex materials on an atomistic scale.