Surface degeneration of W crystal irradiated with low-energy hydrogen ions

• Published in: Scientific reports Vol. 6; no. 1; p. 23738
• Main Authors: Fan, Hongyu, You, Yuwei, Ni, Weiyuan, Yang, Qi, Liu, Lu, Benstetter, Günther, Liu, Dongping, Liu, Changsong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.03.2016; Nature Publishing Group
• Subjects: 639/301/1023/1026; 639/301/119/544; Atomic force microscopy; Degeneration; Electron microscopy; Energy; Humanities and Social Sciences; Hydrogen; Hydrogen ions; Irradiation; multidisciplinary; Radiation; Scanning electron microscopy; Science; Surface temperature; Temperature effects
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep23738

The damage layer of a W (100) crystal irradiated with 120 eV hydrogen ions at a fluence of up to 1.5 × 10 25 /m 2 was investigated by scanning electron microscopy and conductive atomic force microscopy (CAFM). The periodic surface degeneration of the W crystal at a surface temperature of 373 K was formed at increasing hydrogen fluence. Observations by CCD camera and CAFM indicate the existence of ultrathin surface layers due to low-energy H irradiation. The W surface layer can contain a high density of nanometer-sized defects, resulting in the thermal instability of W atoms in the surface layer. Our findings suggest that the periodic surface degeneration of the W crystal can be ascribed to the lateral erosion of W surface layers falling off during the low-energy hydrogen irradiation. Our density functional theory calculations confirm the thermal instability of W atoms in the top layer, especially if H atoms are adsorbed on the surface.