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论文类型： 期刊论文

发表时间： 2012-04-01

发表刊物： JOURNAL OF NUCLEAR MATERIALS

收录刊物： SCIE、EI

卷号： 423

期号： 1-3

页面范围： 164-169

ISSN号： 0022-3115

摘要： We report the energetics and diffusion behavior of H, He, O and C impurities in beryllium as fusion materials from first-principles calculations. Among the six interstitial sites in Be, the basal tetrahedral one is most stable for H. He, O while C prefers to occupy an octahedral site. Solution of 0 impurity in Be is an exothermic process with solution energy of 2.37 eV, whereas solution of H, C and He is an endothermic process (solution energy: 1.55 eV, 2.46 eV, and 5.70 eV, respectively). Overall speaking, these impurities prefer to diffuse along longer paths. The H and O impurities share the same out-of-plane diffusion path via basal tetrahedral sites, while the He and C impurities in Be mainly diffuse via basal tetrahedral and octahedral sites along the (001) plane. Diffusion of He in Be is easiest with a lowest barrier of 0.14 eV: whereas H diffusion in Be is also rather fast with migration energies of 0.4 eV. On the contrary, diffusion of C and O impurities is more difficult because of strong bonding with lattice atoms and high energy barriers of 0.42 and 1.63 eV, respectively. Our theoretical results provide the fundamental parameters for understanding the impurity aggregation and bubble formation in early stage of irradiation damage. (C) 2012 Elsevier By. All rights reserved.