First-principles study of hydrogen capacity in Li2TiO3 crystal

• Published in: International journal of modern physics. C, Computational physics, physical computation Vol. 35; no. 8
• Main Authors: Li, Yan-Wei, Zhang, Yong-Shuai, Meng, Shuai, Yang, Wen, Li, Kun
• Format: Journal Article
• Language: English
• Published: Singapore World Scientific Publishing Company 01.08.2024; World Scientific Publishing Co. Pte., Ltd
• Subjects: Atomic properties; Crystal defects; First principles; Hydrogen; Lattice vacancies; Nuclear fusion; Trapping; Tritium; Li2TiO3; first-principles; hydrogen; vacancy; capacity
• ISSN: 0129-1831; 1793-6586
• DOI: 10.1142/S0129183124500967

Understanding the hydrogen (H) capacity, which represents the tritium capacity in Li2TiO3 crystal has become an important aspect of the tritium release process of nuclear fusion. In this work, a systematic density-functional-theory (DFT) study is performed to investigate the trapping and accumulation of H in Li2TiO3 crystal. In perfect crystal, the H adsorption properties are investigated and the maximum number of trapped H atoms are obtained. In the defect models, by calculating the trapping energy and Bader charge, we find that a Li vacancy can capture four H atoms while the capacity of a Ti vacancy is seven and then other H atoms tend to be trapped by interstitial sites outside the vacancy. Then the H capacity both inside and outside the vacancy in the defect models is studied and analyzed. According to our calculations, crystals containing a vacancy present stronger H trapping abilities than perfect crystals, especially for the crystal with a Ti vacancy. In addition, the increase of H atoms in the vacancy facilitates the formation of the neighboring vacancy so that more H atoms can be accommodated in the crystal with vacancy. Our results reveal the H capacity of different Li2TiO3 models, which provide theoretical support for related tritium release experiments.