›› 2014, Vol. 23 ›› Issue (12): 126105-126105.doi: 10.1088/1674-1056/23/12/126105

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

Raman spectrum study of graphite irradiated by swift heavy ions

翟鹏飞a, 刘杰a, 曾健a b c, 姚会军a, 段敬来a, 侯明东a, 孙友梅a, Ewing Rodney Charlesd   

  1. a Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China;
    b University of Chinese Academy of Sciences, Beijing 100049, China;
    c School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China;
    d Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305-2115, USA
  • 收稿日期:2014-03-26 修回日期:2014-06-27 出版日期:2014-12-15 发布日期:2014-12-15
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 11179003, 10975164, 10805062, and 11005134).

Raman spectrum study of graphite irradiated by swift heavy ions

Zhai Peng-Fei (翟鹏飞)a, Liu Jie (刘杰)a, Zeng Jian (曾健)a b c, Yao Hui-Jun (姚会军)a, Duan Jing-Lai (段敬来)a, Hou Ming-Dong (侯明东)a, Sun You-Mei (孙友梅)a, Ewing Rodney Charlesd   

  1. a Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China;
    b University of Chinese Academy of Sciences, Beijing 100049, China;
    c School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China;
    d Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305-2115, USA
  • Received:2014-03-26 Revised:2014-06-27 Online:2014-12-15 Published:2014-12-15
  • Contact: Liu Jie E-mail:j.liu@impcas.ac.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 11179003, 10975164, 10805062, and 11005134).

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摘要： Highly oriented pyrolytic graphites are irradiated with 40.5-MeV and 67.7-MeV 112Sn-ions in a wide range of fluences: 1× 1011 ions/cm2–1× 1014 ions/cm2. Raman spectra in the region between 1200 cm-1 and 3500 cm-1 show that the disorder induced by Sn-ions increases with ion fluence increasing. However, for the same fluence, the amount of disorder is greater for 40.5-MeV Sn-ions than that observed for 67.7-MeV Sn-ions, even though the latter has a slightly higher value for electronic energy loss. This is explained by the ion velocity effect. Importantly, ～ 3-cm-1 frequency shift toward lower wavenumber for the D band and ～ 6-cm-1 shift toward lower wavenumber for the 2D band are observed at a fluence of 1× 1014 ions/cm2, which is consistent with the scenario of radiation-induced strain. The strain formation is interpreted in the context of inelastic thermal spike model, and the change of the 2D band shape at high ion fluence is explained by the accumulation of stacking faults of the graphene layers activated by radiation-induced strain around ion tracks. Moreover, the hexagonal structure around the ion tracks is observed by scanning tunneling microscopy, which confirms that the strains near the ion tracks locally cause electronic decoupling of neighboring graphene layers.

关键词: Raman spectroscopy, swift heavy ions, highly oriented pyrolytic graphite, strain, ion velocity effect

Abstract: Highly oriented pyrolytic graphites are irradiated with 40.5-MeV and 67.7-MeV 112Sn-ions in a wide range of fluences: 1× 1011 ions/cm2–1× 1014 ions/cm2. Raman spectra in the region between 1200 cm-1 and 3500 cm-1 show that the disorder induced by Sn-ions increases with ion fluence increasing. However, for the same fluence, the amount of disorder is greater for 40.5-MeV Sn-ions than that observed for 67.7-MeV Sn-ions, even though the latter has a slightly higher value for electronic energy loss. This is explained by the ion velocity effect. Importantly, ～ 3-cm-1 frequency shift toward lower wavenumber for the D band and ～ 6-cm-1 shift toward lower wavenumber for the 2D band are observed at a fluence of 1× 1014 ions/cm2, which is consistent with the scenario of radiation-induced strain. The strain formation is interpreted in the context of inelastic thermal spike model, and the change of the 2D band shape at high ion fluence is explained by the accumulation of stacking faults of the graphene layers activated by radiation-induced strain around ion tracks. Moreover, the hexagonal structure around the ion tracks is observed by scanning tunneling microscopy, which confirms that the strains near the ion tracks locally cause electronic decoupling of neighboring graphene layers.

Key words: Raman spectroscopy, swift heavy ions, highly oriented pyrolytic graphite, strain, ion velocity effect

中图分类号:  (Radiation effects on specific materials)

  • 61.82.-d
61.72.Ff (Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)) 61.72.Hh (Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.))