Affiliation:
1. Department of Physics, National University of Defense Technology 1 , Changsha 410073, China
2. Department of Physics and Engineering Physics, University of Saskatchewan 2 , Saskatoon, Saskatchewan S7N 5E2, Canada
3. International Center for Computational Method and Software, College of Physics, Jilin University 3 , Changchun 130012, China
Abstract
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.
Funder
National Key Research and Development Program of China
NSAF Joint Fund
National Natural Science Foundation of China
Science and Technology Innovation Program of Hunan Province under Grant
Postdoctoral Science Foundation of China under Grant
Subject
General Physics and Astronomy
Cited by
1 articles.
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