Lowered tritium diffusivity by decreased site density along Li2TiO3 (001) twin boundary

IF 3.2 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials Pub Date : 2025-08-25 DOI:10.1016/j.jnucmat.2025.156127

Zhonghua Lu , Yanli Shi , Yuchen Liu , Huanhuan Liu , Xiuling Wang , Cong Zhang , Gaoyuan Wang , Jianqi Qi , Tiecheng Lu

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引用次数: 0

Abstract

Li₂TiO₃ is a prominent tritium breeder material with significant potential in the design of nuclear fusion reactors. Given that tritium recovery is closely related to its behavior at grain boundaries (GBs), understanding the dynamics is critical for optimizing the tritium release performance of the breeder material. In this work, we investigate the diffusion of tritium at the Li₂TiO₃ (001) twin GB with density functional theory and kinetic Monte Carlo. Tritium segregation sites are identified and local migration paths between these sites are analyzed. The segregation energies are in the range of -0.43 ∼ 0.06 eV. The activation energies for tritium migration along the a-axis and the b-axis of the GB are 0.54 eV and 0.56 eV, respectively. The diffusion coefficient for tritium along the GB is estimated to be 1.97 × 10^–7 exp(-0.45 eV/K_BT) m²/s. The GB affects tritium diffusivity mainly by raising the activation energy along the b-axis, which consequently lowers the diffusivity by less than one order of magnitude within the 300∼1200 K temperature range compared to the bulk. The decreased tritium site density at the GB compared to bulk is proposed to be the reason for the modified diffusion behaviors by the GB.

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通过降低Li2TiO3（001）孪晶界位密度降低氚扩散系数

Li2TiO3是一种杰出的氚增殖材料，在核聚变反应堆设计中具有重要的潜力。考虑到氚的恢复与其在晶界（GBs）的行为密切相关，了解动力学对于优化增殖材料的氚释放性能至关重要。本文采用密度泛函理论和动力学蒙特卡罗方法研究了氚在Li2TiO3（001）孪晶GB中的扩散。确定了氚的偏析位点，并分析了这些位点之间的局部迁移路径。偏析能在-0.43 ~ 0.06 eV之间。氚沿GB的a轴和b轴迁移的活化能分别为0.54 eV和0.56 eV。氚沿GB的扩散系数估计为1.97 × 10-7 exp(-0.45 eV/KBT) m2/s。GB对氚扩散率的影响主要是通过提高b轴上的活化能来实现的，因此在300 ~ 1200 K温度范围内，与本体相比，其扩散率降低了不到一个数量级。与体块相比，GB处的氚位密度降低，这可能是GB改变扩散行为的原因。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Nuclear Materials 工程技术-材料科学：综合

CiteScore

5.70

自引率

25.80%

发文量

601

审稿时长

63 days

期刊介绍： The Journal of Nuclear Materials publishes high quality papers in materials research for nuclear applications, primarily fission reactors, fusion reactors, and similar environments including radiation areas of charged particle accelerators. Both original research and critical review papers covering experimental, theoretical, and computational aspects of either fundamental or applied nature are welcome. The breadth of the field is such that a wide range of processes and properties in the field of materials science and engineering is of interest to the readership, spanning atom-scale processes, microstructures, thermodynamics, mechanical properties, physical properties, and corrosion, for example. Topics covered by JNM Fission reactor materials, including fuels, cladding, core structures, pressure vessels, coolant interactions with materials, moderator and control components, fission product behavior. Materials aspects of the entire fuel cycle. Materials aspects of the actinides and their compounds. Performance of nuclear waste materials; materials aspects of the immobilization of wastes. Fusion reactor materials, including first walls, blankets, insulators and magnets. Neutron and charged particle radiation effects in materials, including defects, transmutations, microstructures, phase changes and macroscopic properties. Interaction of plasmas, ion beams, electron beams and electromagnetic radiation with materials relevant to nuclear systems.