Uranium nitride is an advanced fuel candidate for a wide variety of advanced nuclear reactors. This work summarizes the first characterization of UN kernels by Raman spectroscopy. First-principles density functional theory calculations were performed to predict the Raman spectra of uranium sesquinitride (UN), uranium dinitride (UN), uranium mononitride (UN), uranium monocarbide (UC), as well as U-N-C (UNC) and a U-N-C-O mixture. A core–shell structure was identified by scanning electron microscopy and Raman spectroscopy imaging. A signal at ∼500 cm was identified on the periphery of the core-shell structure, possibly corresponding to UN and/or UN. This signal broadens and shifts to 470 cm because of the formation of UNC, UNCO or UN structures. The culmination of this work demonstrates the feasibility of using Raman spectroscopy to identify variations in composition and phases in UN kernels.

中文翻译：

---

氮化铀核的拉曼光谱

氮化铀是多种先进核反应堆的先进燃料候选者。这项工作总结了联合国核的拉曼光谱的首次表征。通过第一性原理密度泛函理论计算来预测倍半氮化铀 (UN)、二氮化铀 (UN)、一氮化铀 (UN)、一碳化铀 (UC) 以及 UNC (UNC) 和 UNCO 混合物的拉曼光谱。通过扫描电子显微镜和拉曼光谱成像鉴定了核壳结构。在核壳结构的外围识别出~500 cm处的信号，可能对应于UN和/或UN。由于 UNC、UNCO 或 UN 结构的形成，该信号变宽并移动到 470 厘米。这项工作的最终成果证明了使用拉曼光谱来识别联合国内核中成分和相变化的可行性。