Li Kun, Yang Wen, Wang Wei-Hua, Li Yong-Tang
Shanxi Key Laboratory of Metal Forming Theory and Technology, School of Material Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China.
Department of Electronic Science and Engineering, and Tianjin Key Laboratory of Photo-Electronic Thin Film Device and Technology, Nankai University, Tianjin 300071, China.
Materials (Basel). 2018 Nov 27;11(12):2383. doi: 10.3390/ma11122383.
Li₂TiO₃ is one of the most significant breeder materials and has potential applications in future fusion reactors. Defect models with three types of lithium vacancies were considered to study the diffusion behavior of tritium in Li₂TiO₃ by the density functional theory calculations. The possible tritium adsorption sites inside the lithium vacancy were examined and analyzed. The energy barrier of all diffusion paths between different adsorption sites was calculated and the minimum energy barrier is about 0.45 eV, which indicates that the tritium atom diffuses freely inside the lithium vacancy; when a tritium diffuses across the crystal in the typical three directions, our results reveal that the tritium atom prefers to move along the [010] direction. Furthermore, we found that the minimum energy barrier for the tritium atom to escape the trap of Li vacancy is 0.76 eV. After the tritium jumping out of the Li vacancy, the minimum energy barrier is 0.5 eV for the tritium atom diffusing in the crystal. Therefore, we predict that tritium can easily escape from the trap of the Li vacancy and then diffuse across the crystal. Such results are beneficial to the tritium release process in Li₂TiO₃ and could provide theoretical guidance for the future applications of the Li₂TiO₃ materials.
Li₂TiO₃是最重要的增殖材料之一，在未来的聚变反应堆中有潜在应用。通过密度泛函理论计算，考虑了具有三种锂空位类型的缺陷模型来研究氚在Li₂TiO₃中的扩散行为。研究并分析了锂空位内部可能的氚吸附位点。计算了不同吸附位点之间所有扩散路径的能垒，最小能垒约为0.45 eV，这表明氚原子在锂空位内部可自由扩散；当氚在典型的三个方向上穿过晶体扩散时，我们的结果表明氚原子更倾向于沿[010]方向移动。此外，我们发现氚原子逃离锂空位陷阱的最小能垒为0.76 eV。氚跳出锂空位后，氚原子在晶体中扩散的最小能垒为0.5 eV。因此，我们预测氚能够轻易地从锂空位陷阱中逸出，然后在晶体中扩散。这些结果有利于Li₂TiO₃中的氚释放过程，并可为Li₂TiO₃材料的未来应用提供理论指导。
