  This paper addresses the structural characterisation of a series of U/Fe,
U/Co and U/Gd multilayers. X-ray reflectivity has been employed to investigate
the layer thickness and roughness parameters along the growth direction and
high-angle diffraction measurements have been used to determine the crystal
structure and orientation of the layers. For the case of uranium/transition
metal systems, the interfaces are diffuse and the transition metals are present
in a polycrystalline form of their common bulk phases with a preferred
orientation along the closest packed planes; Fe, bcc (110) and Co, hcp (001),
respectively. The uranium is present in a poorly crystalline orthorhombic,
alpha-U state. In contrast, the U/Gd multilayers have sharp interfaces with
negligible intermixing of atomic species, and have a roughness, which is
strongly dependent on the gadolinium layer thickness. Diffraction spectra
indicate a high degree of crystallinity in both U and Gd layers with
intensities consistent with the growth of a novel hcp U phase, stabilised by
the hcp gadolinium layers.
