Structural investigation of xenon-ion-beam-irradiated glassy carbon.
Structural investigation of xenon-ion-beam-irradiated glassy carbon.
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DOI：
10.1103/physrevb.50.5905
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发表时间：
1994-09
期刊：
影响因子：
--
通讯作者：
D. McCulloch;S. Prawer;A. Hoffman
中科院分区：
文献类型：
--
作者：
D. McCulloch;S. Prawer;A. Hoffman
利用拉曼光谱、横截面透射电子显微镜和电子能量损失光谱监测了在5x1012和6x1016离子/ cm2剂量范围内的320 kev Xe离子辐照玻璃碳的离子束诱导转变。结果表明：(1)离子束使玻璃碳结构非晶化；（ii）非晶化伴随着玻璃碳从初始密度1.55到2.2±0.2 g/ cm3的压实；(3)玻璃碳中约15%的类石墨键在非晶化过程中转化为类金刚石键。玻璃碳向无定形态的转变作为离子剂量的函数发生在两个不同的阶段。对于每原子位移（dpa）达到0.2的损伤水平，离子束的作用是减小石墨晶体的平均尺寸。在0.2 dpa以上，键长和键角偏离理想的石墨三层配位，导致高剂量下完全非晶化。注入层中的非晶化、压实和<s:1> 15% sp - 3键的存在使其表面比生长的玻璃碳具有更强的耐磨性。
Raman spectroscopy, cross-sectional transmission electron microscopy, and electron-energy-loss spectroscopy have been used to monitor the ion-beam-induced transformation in glassy carbon irradiated with 320-keV Xe ions to doses between 5× 10 12 and 6× 10 16 ions/cm 2. It was found that (i) the ion beam amorphizes the glassy carbon structure;(ii) the amorphization is accompanied by a compaction of the glassy carbon from an initial density of 1.55 to 2.2±0.2 g/cm 3; and (iii) approximately 15% of the graphitelike bonds in glassy carbon are converted to diamondlike bonds in the amorphization process. The transformation of glassy carbon to an amorphous state occurs in two distinct stages as a function of ion dose. For damage levels up to 0.2 displacements per atom (dpa) the effect of the ion beam is to decrease the average graphitic crystallite size. Above 0.2 dpa, disorder in bond length and bond angle away from ideal graphitic threefold coordination occurs leading to complete amorphization at high doses. The amorphization, compaction, and presence of≊ 15% sp 3 bonds in the implanted layer of glassy carbon results in a surface layer which is significantly more resistant to abrasion than as-grown glassy carbon.