Communication www.rsc.org/chemcomm CHEMCOMM Complete characterisation of a Sb 2 O 3 /(21,28)SWNT inclusion composite Steffi Friedrichs, a Rüdiger R. Meyer, b Jeremy Sloan,* ac Angus I. Kirkland, b John L. Hutchison c and Malcolm L. H. Green a a Wolfson Catalysis Centre (Carbon Nanotechnology Group), Inorganic Chemistry Laboratory, South Parks Road, Oxford, UK OX1 3QR. E-mail: jeremy.sloan@chem.ox.ac.uk b Department of Materials Science & Metallurgy, Pembroke Street, Cambridge, UK CB2 3QZ c Department of Materials, Parks Road, Oxford, UK OX1 3PH Received (in Cambridge, UK) 13th March 2001, Accepted 12th April 2001 First published as an Advance Article on the web 2nd May 2001 The structure of a one-dimensional crystal of Sb 2 O 3 encap- sulated within a single-walled carbon nanotube and con- formation of the latter have been solved simultaneously by high resolution transmission electron microscopy. In this paper we report the characterisation of a one-dimensional crystal of Sb 2 O 3 , incorporated within a helical (21, 28) single- walled carbon nanotube (SWNT) achieved by object wave restoration from a focal series of high resolution transmission electron microscopy (HRTEM) images.† Within the nano- crystal, the atomic thickness in projection of individual antimony columns was determined and a substantial lattice contraction of the crystal along the tube axis observed. A simultaneous analysis of asymmetric fringe contrast in the tube walls provides convincing evidence for the chiral conformation of the nanotube. SWNTs were produced using a metal catalysed arc synthesis technique similar to a method previously reported 1 and filled by capillary wetting. 2 Energy dispersive X-ray microanalysis (LINK ‘ISIS’ system) performed with a 0.5 nm electron probe confirmed the chemical identity of the filling material. HRTEM simulations, giving the complex wave function of the objects in question, were performed using a standard multislice algo- rithm 3,4 utilising a code provided by Kirkland. 5 Fig. 1(a) shows the experimental restored HRTEM phase image of a 1.45 nm diameter SWNT containing an encapsulated single crystal of Sb 2 O 3 . The right tube wall displays a periodic lattice spacing of 0.224 nm, whereas the contrast variations on the left wall are effectively random. The observed periodic spacing on the right wall corresponds to the centre-to-centre spacing (1.5d C–C = 0.216 nm) between neighbouring ‘zigzag’ rows of carbon atoms in the SWNT wall lattice viewed in projection. The visibility of these spacings is determined by the SWNT conformation, the tilt angle of the cylinder relative to the electron beam and the HRTEM resolution (ca. 0.16 nm). Fig. 2 illustrates the relationship between the observed wall periodicity, nanotube conformation and tilt angle together with corresponding simulations. Atomic coordinates for (n, m) nanotubes were generated by mapping the strip {r | 0 ≤ r · C h < |C h | 2 } of an unrolled hexagonal graphene lattice (with a carbon–carbon distance d C–C = 1.44 nm and lattice vectors a 1 , a 2 ) onto a cylinder surface (Fig. 2). The structure of the SWNT is uniquely defined by the integers (n,m) with n > 0 and 2n/2 < m @ n‡ via the chiral vector C h = na 1 + ma 2 . 6 (n,0) and (n,n) represent the non-chiral zigzag and armchair configurations, respectively. All other (n,m) nanotubes are chiral with (n + m, 2m) being the mirror image of (n,m). The three differing conformation SWNTs shown in Fig. 2 (i.e. the (10,10) tubule in (a), the (18,0) tubule in (b) and the Fig. 1 Composite diagram showing the experimental restored phase image (a), the simulated phase image (b) and the structural model in the observed projection (c) and in end-on view (d), single pixel line profiles through type 1 (e) and type 2 (f) layers, respectively. Fig. 2 (a)–(c) Schematic illustrations of the observable resolution of lattice fringes along SWNT walls of armchair, zigzag and chiral conformations, depending on the conformation, and the tilt angle b. The left column shows the unrolled graphene sheet, illustrating how the orientation of the chiral vector C h w.r.t. the unit vectors a 1 and a 2 defines the rolling of a strip of the width |C h | into a nanotube of a specific conformation and diameter. The middle column displays a modeled fraction of the SWNT, tilted by b = 15° out of the image-plane. The right column shows simulated phase images of the displayed models. This journal is © The Royal Society of Chemistry 2001 DOI: 10.1039/b102348a Chem. Commun., 2001, 929–930 929 Published on 02 May 2001. Downloaded by Brown University on 27/10/2014 20:48:57. View Article Online / Journal Homepage / Table of Contents for this issue