First-principles Study of Hydrogen Behaviors in Plutonium Oxides

doi:10.19596/j.cnki.1001-246x.8118

Abstract

Abstract: In-depth investigation of hydrogen behaviors in Pu-oxide overlayers (mainly PuO₂ and α-Pu₂O₃) is critical for modeling complex induction period of Pu hydriding. Within DFT+U and DFT-D3 schemes, systematic first-principles calculations and ab initio thermodynamic evaluations reveal that hydrogen absorption, dissolution behaviors, and diffusion mechanism in PuO₂ are quite different from those in α-Pu₂O₃, among which highly endothermic absorption and dissolution of hydrogen are primary hydrogen resistance mechanism of PuO₂. Since its difficult recombination, atomic H is preferred existence state in PuO₂, but H will recombine spontaneously in α-Pu₂O₃. In PuO₂, H diffusion is always clinging to O anions, whereas in α-Pu₂O₃, H₂ prefers to migrate along O vacancies with higher barriers. Based on a series of theoretical studies, we conclude that the main interactions between hydrogen and Pu-oxide overlayers are not involved with chemical reactions and intact PuO₂ can effectively inhibit hydrogen permeation.The hydrogen dissolution in α-Pu₂O₃ can be reasonably described by an ideal solid solution model.

Key words: Pu-hydriding, Pu-oxides, hydrogen diffusion and dissolution, first-principles

CLC Number:

ZHANG Le, SUN Bo, SONG Haifeng. First-principles Study of Hydrogen Behaviors in Plutonium Oxides[J]. CHINESE JOURNAL OF COMPUTATIONAL PHYSICS, 2020, 37(5): 595-602.

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