Toshiya Okazaki1

1, AIST, Ibaraki, , Japan

Due to their extraordinary electrical and mechanical properties, carbon nanotubes (CNTs) and graphene are widely regarded as very attractive nanomaterials. For example, CNT production capacity has rapidly increased worldwide. For commercialization of CNT and graphene-based products, the qualities of CNTs and graphene must be controlled. In this talk, we will show effective methods for quality evaluation of CNTs and graphene.
First, the lengths of CNT are estimated by far-infrared (FIR) spectroscopy.1-3 Based on the plasmon resonance model, the length of the clean channel (‘effective length') of CNTs can be deduced by the method. The systematic investigations of the relationship between the mechanical and electrical properties of CNT fibers and the effective lengths of the constituent CNTs is discussed.4,5
Next, lock-in thermography technique is applied for visualizing the network structure of CNTs in composites and evaluation of quality of graphene sheet.6,7 Detection of Joule heating in a biased device enables local structures to be imaged without the influence of heat broadening in a short acquisition time.
A part of this presentation is based on results obtained from a project (P16010) commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

[1] T. Morimoto, S.-K. Joung, T. Saito, D. N. Futaba, K. Hata, T. Okazaki, ACS Nano, 8, 9897-9904 (2014).
[2] T. Morimoto, T. Okazaki, Appl. Phys. Exp., 8, 055101 (2015).
[3] T. Morimoto, Y. Ikeda, M. Ichida, T. Okazaki, Phys. Rev. B, 93, 195409 (2016).
[4] X. Wu, T. Morimoto, K. Mukai, K. Asaka, T. Okazaki, J. Phys. Chem. C, 120, 20419−20427 (2016).
[5] X. Wu, K. Mukai, K. Asaka, T. Morimoto, T. Okazaki, Appl. Phys. Exp., 10, 055101 (2017).
[6] T. Morimoto, S. Ata, T. Yamada, T. Okazaki, submitted.
[7] H. Nakajima, T. Morimoto, Y. Okigawa, T. Yamada, Y. Ikuta, K. Kawahara, H. Ago, T. Okazaki, submitted.