• 文献标题:   Carbon materials with quasi-graphene layers: The dielectric, percolation properties and the electronic transport mechanism
  • 文献类型:   Article
  • 作  者:   LU MM, YUAN J, WEN B, LIU J, CAO WQ, CAO MS
  • 作者关键词:   multiwalled carbon nanotube, quasigraphene layer, dielectric propertie, percolation
  • 出版物名称:   CHINESE PHYSICS B
  • ISSN:   1674-1056
  • 通讯作者地址:   Beijing Inst Technol
  • 被引频次:   9
  • DOI:   10.1088/1674-1056/22/3/037701
  • 出版年:   2013

▎ 摘  要

We investigate the dielectric properties of multi-walled carbon nanotubes (MWCNTs) and graphite filling in SiO2 with the filling concentration of 2-20 wt.% in the frequency range of 10(2)-10(7) Hz. MWCNTs and graphite have general electrical properties and percolation phenomena owing to their quasi-structure made up of graphene layers. Both permittivity epsilon and conductivity sigma exhibit jumps around the percolation threshold. Variations of dielectric properties of the composites are in agreement with the percolation theory. All the percolation phenomena are determined by hopping and migrating electrons, which are attributed to the special electronic transport mechanism of the fillers in the composites. However, the twin-percolation phenomenon exists when the concentration of MWCNTs is between 5-10 wt.% and 15-20 wt.% in the MWCNTs/SiO2 composites, while in the graphite/SiO2 composites, there is only one percolation phenomenon in the graphite concentration of 10-15 wt.%. The unique twin-percolation phenomenon of MWCNTs/SiO2 is described and attributed to the electronic transfer mechanism, especially the network effect of MWCNTs in the composites. The network formation plays an essential role in determining the second percolation threshold of MWCNTs/SiO2.