Structural properties, thicknesses, and qualities of plutonium oxide thin films prepared by polymer assisted deposition

Abstract

Phase purity, morphology, and defect structures on plutonium oxide surfaces likely influence reactivity of plutonium, and high quality PuO2 crystalline substrates are needed to probe the effects of these properties on a model plutonium oxide surface. Indeed, different thin film thicknesses are required for conducting the range of state-of-the-art measurements available for studying these surfaces. In this Article, modification of a polymer-assisted deposition method is employed to grow various film thicknesses of PuO2 on yttria stabilized zirconia (YSZ) substrates, and measurements are carried out to characterize these films. Phase purity and epitaxial qualities of the films are assessed using thin film X-ray diffraction analysis, and the first Grazing Incidence Extended X-ray Absorption Fine Structure measurements carried out on a PuO2 thin film are reported, providing information about the short-range order of the lattice structure. Elemental purity is measured via X-ray photoelectron spectroscopy. Thicknesses and densities of the films are evaluated using neutron reflectivity, revealing that phase-pure PuO2 thin films of high epitaxial quality are formed. Micro-Raman spectroscopy suggests development of structural agglomerates of PuO2 on the surfaces, likely resulting from defects in the lattice match between the PuO2 film and the YSZ substrate.