Resistance–temperature dependence in carbon nanotube fibres Agnieszka Lekawa-Raus a , Kamil Walczak b , Gregory Kozlowski c , Mariusz Wozniak a , Simon C. Hopkins a , Krzysztof K. Koziol a, * a Department of Materials Science and Metallurgy, University of Cambridge, CB3 0FS Cambridge, UK b Department of Chemistry and Physical Sciences, Pace University, 1 Pace Plaza, New York, NY 10038, USA c Department of Physics, Wright State University, Dayton, OH 45435, USA ARTICLE INFO Article history: Received 12 September 2014 Accepted 30 November 2014 Available online 5 December 2014 ABSTRACT The electrical transport of a carbon nanotube assembly is determined by its morphology and composition. These vary with the assembly production processes and post-process treatments applied. Here, we present the study of the electrical – structural dependence of wire like assemblies of carbon nanotubes i.e. carbon nanotube fibres produced via float- ing catalyst chemical vapour deposition processes. We propose that the analysis of resis- tance – temperature characteristics of the fibres provides vast amount of information for the assessment of the quality of the fibres and thus the efficacy of fibre production and post-production processes. To aid qualitative and quantitative analysis of the experimental results we propose a new universal model which allows the fitting of experimental data in the full range of temperatures and a straightforward comparison of the recorded characteristics. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Carbon nanotube (CNT) assemblies have a potential to become a conductive material of the future for electrical and electronic devices [1,2]. Of particular interest are CNT fibres i.e. wire-like macroscopic assemblies of axially aligned CNTs, for the application as the next generation of electrical wires [1]. It has been recently shown theoretically that a fibre made of defectless single-walled armchair nanotubes of one chirality, with precise length of contacts between them, should conduct as one nanotube i.e. transport electrons bal- listically (without scattering) [3]. Such fibre would consider- ably outperform any traditional metallic conductors. However, as the structure of currently produced fibres has not yet been fully controlled this anticipated conduction is still not possible. The current fibres can comprise nanotubes of random lengths, chiralities and number of walls [4–7]. The CNTs can be defected and the whole structure – disor- dered having e.g. misalignments or areas of poor condensa- tion as well as impurities or dopants [5,7–9]. All these aspects will decidedly influence the current flow in the fibres. Full characterisation of the complex morphology of every assembly requires laborious, statistical microscopic measure- ments and it is very difficult to predict the electrical proper- ties of the given fibre and thus judge the efficacy of its production process [4]. Therefore, any straightforward tech- nique aiding the electrical characterisation of the fibres in correlation with their morphology, would be highly useful. An interesting method for such purpose is the measurement of the dependence of the electrical resistivity of the fibres on http://dx.doi.org/10.1016/j.carbon.2014.11.062 0008-6223/Ó 2014 Elsevier Ltd. All rights reserved. * Corresponding author. E-mail address: kk292@cam.ac.uk (K.K. Koziol). CARBON 84 (2015) 118 – 123 Available at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/carbon