We studied in-situ the interaction of sodium metal with UO_2+x (0 ≤ x ≤ 1) using thin films prepared by sputter deposition on Au substrate. X-ray Photoelectron Spectroscopy (XPS) and Grazing Incidence X-Ray Diffraction (GIXRD) characterized films before and after interaction. The results show that sodium does not reduce stoichiometric UO₂ at room temperature. Plasmon loss peaks, observed at the Na-1s photoemission (PE) line, are characteristic of metallic sodium particles, and point to a weak interaction between sodium and UO₂. The oxidation of the sodium at room temperature takes place only on hyper-stoichiometric uranium dioxide films. Indeed, sodium deposition on UO_2+x (0 < x ≤ 1), eventually results in the complete reduction of U(VI) down to U(IV). Molecular and atomic oxygen affect differently the oxidation of uranium and sodium. The wetting of the gold by the sodium is much more important when sodium is oxidised by atomic oxygen. This leads to a shift of the Na-1s core level peak, while molecular oxygen gives a peak broadening without shift. Atomic oxygen seems to play the same role as the interstitial oxygen present in the UO_2+x film. The oxygen dissociation may be the limiting step of sodium oxidation on gold and on UO₂. Heat treatment of sodium on UO₃ at about 773 K leads to the formation of the NaUO₃ film as demonstrated by a quantitative analysis by XPS and GIXRD. The results show also that once U(V) is formed, it stays stable up to at least 973 K, the temperature at which shrinkage of the film is observed.

我们使用在Au基板上溅射沉积制备的薄膜，就位研究了钠金属与UO _{2 + x}（0≤x≤1）的相互作用。X射线光电子能谱（XPS）和掠入射X射线衍射（GIXRD）表征了相互作用前后的薄膜。结果表明，钠在室温下不降低化学计量的UO ₂。在Na-1的光发射（PE）线处观察到的等离子损失峰是金属钠颗粒的特征，并且表明钠和UO ₂之间的相互作用较弱。钠在室温下的氧化仅发生在超化学计量的二氧化铀膜上。实际上，UO _{2 + x}上的钠沉积（0 <x≤1），最终导致U（VI）完全减小到U（IV）。分子氧和原子氧对铀和钠的氧化有不同的影响。当钠被原子氧氧化时，钠对金的润湿作用更为重要。这导致Na-1 s核心能级峰移动，而分子氧给出的峰变宽而没有移动。原子氧似乎与UO _{2 + x}膜中存在的间隙氧具有相同的作用。氧离解可能是钠在金和UO ₂上氧化的限制步骤。在约773 K的UO ₃上对钠进行热处理会形成NaUO ₃如XPS和GIXRD的定量分析所证明。结果还表明，一旦形成了U（V），它就可以稳定到至少973 K（观察到薄膜收缩的温度）。