This work focuses on PuCO-type phase formation at the surface of δ-Pu at temperatures above 300 °C under low oxygen partial pressure. Its growth was characterised by XRD and XPS and was found to follow parabolic kinetics law. This oxycarbide formation was thermodynamically supported by CALPHAD calculations. XPS investigations of PuCO phase reveal a singular plutonium oxidation state never observed in plutonium oxides (i.e. PuO₂ or Pu₂O₃). Furthermore, the oxycarbide presence on the sample surface strongly impacts the oxidation rate in oxygen atmosphere, reducing drastically the other oxide growth.

中文翻译：

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PuO/PuCO型相的表征及其对δ-钚氧化动力学的影响

这项工作的重点是在 300°C 以上的温度和低氧分压下在 δ-Pu 表面形成 PuCO 型相。其生长通过 XRD 和 XPS 表征并发现遵循抛物线动力学定律。这种碳氧化物的形成得到了 CALPHAD 计算的热力学支持。PuCO 相的 XPS 研究揭示了从未在钚氧化物（即 PuO ₂或 Pu ₂ O ₃）中观察到的单一钚氧化态。此外，样品表面的碳氧化物会强烈影响氧气气氛中的氧化速率，从而大大减少其他氧化物的生长。