Investigation on the effect of surface orientations on helium behavior using first-principles

Abstract

The structure and stability of the Y₂O₃ surface, along with helium (He) behavior near the surface, were investigated using first-principles calculations. Surface energy, dissolution, diffusion, and clustering behaviors were analyzed to explore He bubble nucleation mechanisms. Among the studied surface models, the O-Ter termination of the Y₂O₃ (1 1 1) surface demonstrated the highest stability due to its stoichiometric structure. Dissolution and diffusion analyses revealed that He is most stable at the (4 2 2) surface but is more readily released near the (1 0 0) surface under irradiation. Multi-He cluster configurations near the (1 1 1) surface indicated that a low-dissolution energy region can accommodate up to five He atoms before forming a nucleation center. These clusters initially grow parallel to the surface and later extend perpendicularly, ultimately forming He bubbles. The results provide critical insights into He behavior near Y₂O₃ surfaces in ODS-W materials.