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Structures and properties of uranium– niobium intermetallic compounds under high pressure: A first principles stud

Bao, Nanyun and Tong, Qunchao and Guo, Fangyu and Zhang, Shen and Kang, Dongdong and Akinpelu, A. and Lv, Jian and Yao, Yansun and Dai, Jiayu (2023) Structures and properties of uranium– niobium intermetallic compounds under high pressure: A first principles stud. Journal Applied Physics, 133 (9). ISSN Online ISSN 1089-7550 Print ISSN 0021-8979

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Metallic uranium-based alloys, with d-transition metals such as Nb, Mo, and Zr, are promising candidates for actinide fuel. For this purpose, their behaviors under changing physical stimuli need to be understood. Here, we systematically investigate U–Nb intermetallic compounds and predict new compound formations under different pressures using the first-principles swarm-intelligence structure searching method. Two new compounds (U1Nb6 and U2Nb1) were identified to be thermodynamically stable at ambient and high pressures. U1Nb6 has a triclinic symmetry that is stable in the pressure range of 0–200 GPa, while U2Nb1 has a hexagonal closely packed structure at low pressure and transforms to a simple hexagonal lattice at 20 GPa. Other compounds, particularly U-rich ones (U3Nb1, U4Nb1, U5Nb1, and U6Nb1), are found metastable at ambient and high pressures, and all have orthorhombic structures. The structural, vibrational, electronic, and mechanical properties of predicted U-rich compounds were thoroughly studied using density-functional theory. The results of phonon spectra and elastic constant show that the predicted new structures are dynamically and mechanically stable in the corresponding pressure range. Also, these newly identified U-rich compounds exhibit strong composition dependence, and the pressure-induced enhancements of structural stability and mechanical performances are evident. These findings shall enrich the understanding of U-based alloys and serve as meaningful predictions for experimental research in the future.

Item Type: Article
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Divisions: Faculty of Engineering, Science and Mathematics > School of Physics
Depositing User: nwokealisi
Date Deposited: 07 Jun 2024 15:09
Last Modified: 07 Jun 2024 15:09

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