In this study, we investigated the type of dislocation loops formed in the proton-irradiated uranium-nitrogen-oxygen (U-N-O) system, which involves uranium mononitride (UN), uranium sesquinitride (α-U₂N₃), and uranium dioxide (UO₂) phases. The dislocation loop formation is examined using specimens irradiated at 400°C and 710°C. Based on the detailed transmission-based electron microscopy characterization with i) the morphology-based on-zone and ii) the invisibility-criterion based two-beam condition imaging techniques, only a single type of dislocation loop in each phase is found: a/2⟨110⟩, a/2⟨111⟩, or a/3⟨111⟩ dislocation loops in UN, α-U₂N₃, and UO₂ phases, respectively. Molecular statics calculations for the formation energy of perfect and faulted dislocation loops in the UN phase indicate a critical loop size of ∼ 6 nm, above which perfect loops are thermodynamically favorable. This could explain the absence of faulted loops in the experimental observation of the irradiated UN phase at two temperatures. This work will enhance the understanding of irradiation induced microstructural evolution for uranium mononitride as an advanced nuclear fuel for the next-generation nuclear reactors.

在这项研究中，我们研究了在质子辐照的铀-氮-氧 (UNO) 系统中形成的位错环的类型，其中包括一氮化铀 (UN)、倍半氮化铀 (α-U ₂ N ₃ ) 和二氧化铀 ( UO ₂ ) 相。使用在 400°C 和 710°C 下辐照的样品检查位错环的形成。基于详细的基于透射电子显微镜表征与 i) 基于形态的区域和 ii) 基于不可见标准的双光束条件成像技术，在每个阶段只发现一种类型的位错环：a/ UN、α-U ₂ N ₃和 UO _{2 中的}2⟨110⟩、a/2⟨111⟩ 或 a/3⟨111⟩ 位错环相，分别。UN 相中完美和有错位错环的形成能的分子静力学计算表明，临界环尺寸约为 6 nm，超过该尺寸时，完美环在热力学上是有利的。这可以解释在两个温度下辐照 UN 相的实验观察中不存在故障回路。这项工作将增进对作为下一代核反应堆先进核燃料的一氮化铀的辐照诱导微观结构演变的理解。