Kuganathan Navaratnarajah, Chroneos Alexander, Grimes Robin W
Department of Materials, Imperial College London, London, SW7 2AZ, UK.
Faculty of Engineering, Environment and Computing, Coventry University, Priory Street, Coventry, CV1 5FB, UK.
Sci Rep. 2019 Sep 20;9(1):13612. doi: 10.1038/s41598-019-50089-0.
The nanoporous oxide 12CaO·7AlO (C12A7) can capture large concentrations of extra-framework species inside its nanopores, while maintaining its thermodynamical stability. Here we use atomistic simulation to predict the efficacy of C12A7 to encapsulate volatile fission products, in its stoichiometric and much more effective electride forms. In the stoichiometric form, while Xe, Kr and Cs are not captured, Br, I and Te exhibit strong encapsulation energies while Rb is only weakly encapsulated from atoms. The high electronegativities of Br, I and Te stabilize their encapsulation as anions. The electride form of C12A7 shows a significant enhancement in the encapsulation of Br, I and Te with all three stable as anions from their atom and dimer reference states. Successive encapsulation of multiple Br, I and Te as single anions in adjacent cages is also energetically favourable. Conversely, Xe, Kr, Rb and Cs are unbound. Encapsulation of homonuclear dimers (Br, I and Te) and heteronuclear dimers (CsBr and CsI) in a single cage is also unfavourable. Thus, C12A7 offers the desirable prospect of species selectivity.
纳米多孔氧化物12CaO·7AlO（C12A7）能够在其纳米孔内捕获高浓度的骨架外物种，同时保持其热力学稳定性。在此，我们使用原子模拟来预测C12A7以其化学计量形式以及更有效的电子化物形式封装挥发性裂变产物的效果。在化学计量形式下，虽然氙、氪和铯未被捕获，但溴、碘和碲表现出很强的封装能，而铷仅以原子形式被弱封装。溴、碘和碲的高电负性使其以阴离子形式稳定封装。C12A7的电子化物形式在溴、碘和碲的封装方面有显著增强，这三种元素均以阴离子形式从其原子和二聚体参考态稳定存在。多个溴、碘和碲以单个阴离子形式连续封装在相邻笼中在能量上也是有利的。相反，氙、氪、铷和铯未被束缚。单个笼中同核二聚体（溴、碘和碲）和异核二聚体（溴化铯和碘化铯）的封装也是不利的。因此，C12A7提供了物种选择性的理想前景。
