Nano-Graphitization in Amorphous Carbon Films via Electron Beam Irradiation and the Iron Implantation
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0960-N12-04
Nano-Graphitization in Amorphous Carbon Films via Electron Beam Irradiation and the Iron Implantation Eiji Iwamura1 and Tatsuhiko Aizawa2,3 1 R & D Center, Arakawa Chemical Industry, Ltd., Osaka, 538-0053, Japan 2 Department of Materials Science and Engineering, University of Toronto, Toronto, M5S 3E4, Canada 3 AsiaSEED Institute, Tokyo, 104-0033, Japan
ABSTRACT Nano-graphitization from amorphous carbon state is assisted by the electron beam irradiation. An inter-columnar region in the amorphous carbon films with low atomic and electron densities is controlled to have a graphitic structure by relatively low dose electron beam irradiation. This amorphous carbon – beam interaction generates a new type of carbon hybrids where the graphitic inter-columnar network is embedded into amorphous carbon columns. This hybrid film has an exotic mechanical and tribological response: extraordinary reversible deformability up to 8 – 10 % in normal strain, high wearing resistance and low friction at high normal pressure. A combination of iron-ion implantation with this electron irradiation provides us the other method of nano-graphitization process. An amorphous carbon film including the implanted iron atoms is chemically modified to have a columnar graphitic structure by the electron beam irradiation. In this post-implantation electron beam irradiation, the basic graphitic units with 1-2 nm in size are controlled to align vertically along the film thickness. This type of nano-graphitization has a strong dependency on the iron doses before electron beam irradiation. The above two types of nano-graphitization provides us a new tool to explore the functionalized structural thin films in application. INTRODUCTION Carbon is a typical material having two atomic structures: i.e. crystalline structure by graphitization, formation of diamonds or fullerene-structuring [1] and amorphous structure by DLC (Diamond-Like Carbon) coating and formation of glassy carbon [2]. When lattice defects are introduced into a nano-crystalline material, they result in a grain boundary of nano-crystals. No changes occur in the atomic structure. Introduction of defects into glassy solids in the form of glass/glass interfaces is recently high-lighted to control the atomic structure in solid [3]. Through precise molecular dynamics calculations, nano-glasses having the spacing between adjacent glass/glass interfaces in a few nano-meters, play a key to modify the atomic structure on the entire glassy solid. Authors have proposed the surface nano-structuring process to modify the starting amorphous structure and to have nano-columnar structure via the electron beam irradiation and the metallic ion implantation [4-6]. Different from [7], this modification takes place under much lower dose range in electron beam irradiation than experienced in use of SEM and TEM. In the present paper, this nano-structuring is revisited as a new processing to modify the entire atomic structure by utilizing defects in the amorphous solid and by introducing defects
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