S. Iijima

Faculty of Science and Technology, Meijo University,

National Institute of Advanced Industrial Science and Technology /Nanotube Research Center, Nagoya University and NEC

 

Firstly, the state of the art of synthesis of various nano-carbon materials that we have studied so far will be reviewed with the emphasis on the key points of the synthesis. One of challenge in the formation of SWCNT is to control its diameter and chirality, for which we tried to grow SWCNTs using metal catalyst of uni-sized metal clusters. The usual size of carbon nanohorn (CNH) aggregates is about 80 nm in diameter but its smaller size of less than 30nm is needed for a bio-medical application purpose (drug carrier for drug delivery system ) because of their higher permeation through biological cell membranes [1]. The small CNHs have been successfully realized by optimizing parameters for the growth of CNHs in CO2 laser ablation method of a carbon rod. The success is attributed to understanding of the condensation of carbon vapor in the CO2 laser ablation. Formation of a large size graphene sheet by thermal CVD method using a copper substrate foil has been reported [2]. The method requires a high temperature CVD reactor (near 1000℃), so that it cannot be used in a conventional Si device process and therefore an alternative low temperature synthesis of graphene is needed. For this purpose we developed a new micro-wave CVD method which has been developed originally for the nano-diamond film growth at low temperature down to room temperature [3]. We shall demonstrate the growth of an A4-size graphene sheet at 300℃.

In the last half part of the presentation will be concerned with structural characterization of nano-carbon materials using atom-resolution electron microscopes as well as other characterization methods of Raman, photoluminescence and optical absorption spectroscopy, etc The advantage of high resolution electron microscopy (HRTEM) over other techniques is to be able to characterize local atomic structures such as lattice defects and edge structures of nano materials which cannot be studied in conventional techniques. Another emphasis of HRTEM will be on dynamic observation of a reaction process which is not available for other high resolution probe microscope techniques such as STM. In terms of application of nano-carbon materials SWCNTs should be mentioned as an excellent TEM specimen support material. The SWCNTs were found to protect specimens from the electron beam irradiation damage when enclosed inside the central hollows of SWCNTs. Some examples of above mentioned observations will be demonstrated: latest results on structural characterization of carbon nanotubes [4-9], graphene [10], and boron nitride thin films [11], including “monatomic carbon strings that have been successfully made and observed in our laboratory [12].

 

1)            M. Zhang, et al. PNAS, 105, 14773(2008).

2)            S. Bae, et al. Nature Nanotech., (2010).

3)            M. Hasegawa et al., PRB, (2010).

4)            K. Suenaga, et al. Nature Nanotech. 2, 358 (2007)

5)            Z. Liu, et al., Nature Nanotech., 2, 422 (2007).

6)            Y. Sato, et al., Nano Lett, 7, 3704 (2007).

7)            C. H. Jin, et al., Nature Nanotech. 3, 17 (2008).

8)            C. H. Jin, et al., PRL, 101, 176102(1)-(4) (2008).

9)            M. Koshino, et al., Nature Chemistry (2010).

10)            Z. Liu, et al., PRL, 102, 015501 (1)-(4) (2009). 

11)            C. H. Jin, et al., PRL, 102, 195505 (1)-(4) (2009). 

12)            C. H. Jin, et al., PRL, 102, 205501 (1)-(4) (2009).

 

Professor Sumio Iijima is the discoverer of carbon nanotubes. Iijima's 1991 paper generated unprecedented interest in the carbon nanostructures and has since fueled intense research in the area of nanotechnology. For this and other work, Sumio Iijima was awarded, together with Louis Brus, the inaugural Kavli Prize for Nanoscience in 2008.

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