Symington A R, Molinari M, Brincat N A, Williams N R, Parker S C
1 Department of Chemistry , University of Bath , Claverton Down , Bath BA2 7AY , UK.
2 Department of Chemistry , University of Huddersfield , Queensgate , Huddersfield HD1 3DH , UK.
Philos Trans A Math Phys Eng Sci. 2019 Aug 26;377(2152):20190026. doi: 10.1098/rsta.2019.0026. Epub 2019 Jul 8.
An important challenge for modelling transport in materials for energy applications is that in most applications they are polycrystalline, and hence it is critical to understand the properties in the presence of grain boundaries. Moreover, most grain boundaries are not pristine stoichiometric interfaces and hence dopants are likely to play a significant role. In this paper, we describe our recent work on using atomistic molecular dynamics simulations to model the effect of doped grain boundaries on oxygen transport of fluorite structured UO. UO, much like other fluorite grain boundaries, are found to be sinks for oxygen vacancy segregation relative to the grain interior, thus facilitating oxygen transport. Fission products further enhance diffusivity via strong interactions between the impurities and oxygen defects. Doping produces a striking structural alteration in the Σ5 class of grain boundaries that enhances oxygen diffusivity even further. This article is part of a discussion meeting issue 'Energy materials for a low carbon future'.
对于为能源应用而对材料中的输运过程进行建模而言，一个重要的挑战在于，在大多数应用中它们都是多晶的，因此了解晶界存在时的特性至关重要。此外，大多数晶界并非纯净的化学计量界面，所以掺杂剂很可能发挥重要作用。在本文中，我们描述了我们最近关于使用原子分子动力学模拟来模拟掺杂晶界对萤石结构UO₂氧输运影响的工作。UO₂与其他萤石晶界类似，相对于晶粒内部而言，被发现是氧空位偏析的汇，从而促进了氧的输运。裂变产物通过杂质与氧缺陷之间的强相互作用进一步提高扩散率。掺杂会在Σ5类晶界中产生显著的结构改变，进而进一步提高氧扩散率。本文是“低碳未来的能源材料”讨论会议专题的一部分。
