Goswami Kamal N, Murphy Samuel T
Engineering Department, Lancaster University, Bailrigg, Lancaster LA1 4YW, U.K.
J Phys Chem C Nanomater Interfaces. 2020 Jun 11;124(23):12286-12294. doi: 10.1021/acs.jpcc.0c02551. Epub 2020 May 13.
Lithium metatitanate, LiTiO, is a leading candidate for application as a tritium breeding material in a future fusion reactor. Following transmutation of lithium, the tritium must escape the crystal in order to be extracted for use in the fusion plasma. The rate-limiting step to release tritium from the LiTiO pebbles is diffusion through the crystal grains. In this work, the activation barriers for tritium diffusion have been calculated using density functional theory. The results show that tritium can diffuse as an interstitial with a barrier of 0.52 eV. However, when a tritium ion becomes bound to a lithium vacancy defect, the energy required to either detrap the tritium from the vacancy or for the cluster to diffuse increases to >1 eV. Overall, these results suggest that the introduction of lithium vacancies due to Li burn-up may lead to an increase in tritium retention in the pebbles.
偏钛酸锂（LiTiO）是未来聚变反应堆中用作氚增殖材料的主要候选物。锂发生嬗变后，氚必须从晶体中逸出才能被提取出来用于聚变等离子体。从LiTiO球粒中释放氚的限速步骤是通过晶粒的扩散。在这项工作中，利用密度泛函理论计算了氚扩散的活化能垒。结果表明，氚可以以间隙原子的形式扩散，能垒为0.52电子伏特。然而，当一个氚离子与一个锂空位缺陷结合时，将氚从空位中解捕或使团簇扩散所需的能量增加到>1电子伏特。总体而言，这些结果表明，由于锂的燃耗而引入的锂空位可能会导致球粒中氚保留量的增加。
