Stability and isolation of uranium carbide phases in thin film systems

Polycrystalline uranium carbide (UC x ) and epitaxial single crystal uranium monocarbide (UC) thin films have been synthesised using DC magnetron sputtering. By correlating X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements, it was revealed that UC x surfaces maintained a NaCl-type cubic structure whilst exhibiting a range of UC stoichiometries. Epitaxial [001]-oriented UC was isolated and stabilised upon the [001] ∥ [1 1 ̄ 02] Nb/Al 2 O 3 system, with in- and out-of-plane lattice parameters of a ( 024 ) = 4.9875(5) Å and a ( 002 ) = 4.96546(7) Å, respectively. Through XPS area analysis of the U- 4 f and C- 1 s core levels, this sample was found to be stoichiometric within experimental uncertainty. This methodology presents a route to explore the physical structure and fundamental chemical properties of individual carbide phases. • We show the fabrication of uranium carbide phases by DC magnetron sputtering. • Uranium monocarbide films were epitaxially matched to [1 1 ̄ 02] Al 2 O 3 . • X-ray diffraction and x-ray spectroscopy was used to analyse each phase.