The critical role of hydrogen on the stability of oxy-hydroxyl defect clusters in uranium oxide
The critical role of hydrogen on the stability of oxy-hydroxyl defect clusters in uranium oxide
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DOI：
10.1039/c8ta02817f
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发表时间：
2018-06
影响因子：
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通讯作者：
Joseph M. Flitcroft;M. Molinari;Nicholas A. Brincat;Nicholas R. Williams;M. Storr;G. C. Allen;S. C. Parker
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文献类型：
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作者：
Joseph M. Flitcroft;M. Molinari;Nicholas A. Brincat;Nicholas R. Williams;M. Storr;G. C. Allen;S. C. Parker
尽管大量的工作应用从头算技术来模拟缺陷对氧化物的机械、结构和电子特性的作用，但几乎没有关于被困氢的作用的研究，尽管它几乎总是存在的。我们提出了一个识别可逆和不可逆氢阱的框架。我们证明了氧羟基缺陷的热力学稳定性是由形成能和结合能的相互作用决定的。这一框架适用于所有氧化物，是描述氢在宏观水平上的溶解度和扩散性所必需的。对于核能中最重要的锕系氧化物氧化铀，氢显著影响氧缺陷团簇的稳定性，随着局部氢浓度的增加，形成不可逆陷阱。至关重要的是，氢稳定了孤立的威利斯星团，以其发现者的名字命名，最初于1963年报道，随后所有的从头计算都预测它是不稳定的，但当然，没有一个考虑到氢。
Despite considerable work applying ab initio techniques to model the role of defects on mechanical, structural and electronic properties of oxides, there has been little on the role of trapped hydrogen, despite it being virtually always present. We propose a framework for identifying reversible and irreversible hydrogen traps. We demonstrate that the thermodynamic stability of oxy-hydroxyl defects is defined by an interplay of formation and binding energies. This framework is applicable to all oxides and is essential for describing the solubility and diffusivity of hydrogen at the macroscopic level. For the most important actinide oxide in nuclear energy, uranium oxide, hydrogen significantly impacts the stability of oxygen defect clusters, and with increased local hydrogen concentration it forms irreversible traps. Crucially, hydrogen stabilises isolated Willis clusters, named after their discoverer and originally reported in 1963, which all subsequent ab initio calculations have predicted to be unstable, but of course, none considered hydrogen.