R.Vajtai

Carbon nanotubes: optimized growth for applications and practical use of large CNT structures

Robert Vajtai^1*, Géza Tóth^2, Krisztián Kordás^2, Xiaohong An^3, Pulickel M. Ajayan^1

^1 Department of Mechanical Engineering & Materials Science, Rice University, Houston, TX 77005 USA
^2 Microelectronics and Materials Physics Laboratories, Department of Electrical and Information Engineering, and EMPART research group of Infotech Oulu, P.O. Box 4500, FIN-90014 University of Oulu, Finland
^3 Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY
*Robert.Vajtai@rice.edu

Carbon nanotubes attracted large-scale scientific interest and their properties are well-studied for the cases when theoretical model work, and at the same time growth routes and proof of the concept applications were demonstrated (see e.g. Ref. 1). In this talk I briefly summarize our latest result on the most important parameters of multiwalled carbon nanotube growth via the floating catalyst Ferrocene-Xylene route applied earlier with success to create large CNT structures [2]. We investigated the kinetics [3] of the process both experimentally and theoretically and optimized the parameters for carbon nanotube length and also for their quality. These studies were used to reach macroscopic carbon nanotube structures with unique properties optimized to use them as synergistic units. In the main part of the talk I focus on characterization of the structures and their recent applications. Aligned carbon nanotube forests grown with different methods showed wide range of density depending on growth parameters; the physical properties of these films, e.g. compressibility, optical absorbance, thermal and electrical conductivity are unparalleled. To demonstrate the usefulness of these properties I will cite laboratory level applications. First a chip cooler setup [4], made of aligned multiwalled carbon nanotube forest will be presented, where the cooling performance of the device is comparable to a copper cooler having similar geometry; however, the carbon nanotube cooler is much lighter, mechanically stronger and it has more potential for further optimization. Another family of application is printing carbon nanotubes from different kind of “inks” [5-6]. The most interesting feature of this use is the fact that different coverage of the carbon nanotube film results in either low resistance Ohmic (for high coverage) or a nonlinear (for low coverage) behavior which latter one can be driven by gate voltage [6]. Via controlled amount of materials printed on the multi-micrometer scale the method can prepare complete electronic circuits with active elements and wires made of the same carbon nanotube ink without requiring any expensive pre-selection of semi-conductive and metallic tubes. These applications, together with several other, shortly mentioned ones, outdraw the possibilities that large scale, organized carbon nanotube structures inherently infer.


Video Content Length 30:09 Copyright © 2008 Vajtai et al

References

[1] P.M. Ajayan, Chemical Reviews 99, 1787 (1999).
[2] B.Q. Wei, R. Vajtai, Y. Jung, J. Ward, R. Zhang, G. Ramanath and P.M. Ajayan, Nature 416, 495 (2002).
[3] N. Halonen, K. Kordás, G. Tóth, T. Mustonen, J. Mäklin, J. Vähäkangas, P. M. Ajayan and R. Vajtai, J. Phys. Chem. C 112, 6723 (2008).
[4] K. Kordás, G. Tóth, P. Moilanen, M. Kumpumäki, J. Vähäkangas, A. Uusimäki, R. Vajtai, and P. M. Ajayan, Appl. Phys. Lett. 90, 123105 (2007).
[5] K. Kordás, T. Mustonen, G. Tóth, H. Jantunen, M. Lajunen, C. Soldano, S. Talapatra, S. Kar, R. Vajtai and P. M. Ajayan, Small 2, 1021 (2006).
[6] T. Mustonen, J. Mäklin, K. Kordás, N. Halonen, G. Tóth, J. Vähäkangas, H. Jantunen, S. Kar, P. M. Ajayan, R. Vajtai, P. Helistö and H. Seppä, Phys. Rev. B 77, 125430 (2008).

Citation:
R. Vajtai, G. Toth, K. Kordas, X.H. An, and P. M. Ajayan,
OAtube Nanotechnology 1, 1006 (2008). http://www.oatube.org/2008/10/rvajtai.html