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石墨和纳米碳中缺陷和电子密度随温度的变化
引用本文:黄宇阳,郝文博,岳丽,黄乐,胡益丰,邓文. 石墨和纳米碳中缺陷和电子密度随温度的变化[J]. 低温物理学报, 2006, 28(3): 242-245
作者姓名:黄宇阳  郝文博  岳丽  黄乐  胡益丰  邓文
作者单位:广西大学物理科学与工程技术学院,南宁,530004;广西大学物理科学与工程技术学院,南宁,530004;广西大学物理科学与工程技术学院,南宁,530004;广西大学物理科学与工程技术学院,南宁,530004;广西大学物理科学与工程技术学院,南宁,530004;广西大学物理科学与工程技术学院,南宁,530004
基金项目:国家自然科学基金,广西大学校科研和教改项目
摘    要:测量了石墨和纳米碳在不同温度下的正电子寿命谱,研究了石墨和纳米碳中缺陷和电子密度随温度的变化.结果表明,纳米碳中缺陷的开空间和缺陷浓度分别大于和高于石墨晶体;纳米碳的平均自由电子密度低于石墨晶体.当温度从25K升至295K时,石墨和纳米碳中的平均自由电子密度随温度的升高而下降:石墨晶体中的自由电子密度随温度的升高变化较小;纳米碳的自由电子密度随温度的升高变化较大.随着温度的升高,石墨和纳米碳中的热空位数量增多,而且这些空位可迁移至微孔洞的内表面使微孔洞的开空间增大.

关 键 词:正电子湮没  石墨  纳米碳  微观缺陷  电子密度
收稿时间:2005-11-15
修稿时间:2005-11-15

VARIATION OF DEFECTS AND ELECTRON DENSITY IN GRAPHITE AND NANOCRYSTALLINE CARBON WITH TEMPERATURES
Huang Yu-Yang,Hao Wen-Bo,Yue Li,Huang Le,Hu Yi-Feng,Deng Wen. VARIATION OF DEFECTS AND ELECTRON DENSITY IN GRAPHITE AND NANOCRYSTALLINE CARBON WITH TEMPERATURES[J]. Chinese Journal of Low Temperature Physics, 2006, 28(3): 242-245
Authors:Huang Yu-Yang  Hao Wen-Bo  Yue Li  Huang Le  Hu Yi-Feng  Deng Wen
Affiliation:Huang Yu-Yang Hao Wen-Bo Yue Li Huang Le Hu Yi-Feng Deng Wen~ 1
Abstract:Positron lifetime spectra for graphite and nanocrystalline carbon at different temperatures have been measured. The variation of defects and electron density in graphite and nanocrystalline carbon with temperatures has been studied. The results show that the concentration and open volume of defects in nanocrystalline carbon is higher/larger than that in graphite; the mean free electron density in nanocrystalline carbon is lower than that in graphite. As the temperature increases from 25K to 295K, the mean free electron density of nanocrystalline and graphite decrease: the magnitude of the decrease of the mean free electron density of nanocrystalline is higher than that of graphite. With the increase of temperature, the amount of thermal vacancies of nanocrystalline and graphite increase, furthermore, these thermal vacancies may migrate to the inner surfaces of microvoids and increase the open volume of the microvoids.
Keywords:Positron annihilation   graphite   nanocrystalline carbon   defects   electronic density
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