Steffi Friedrichs

The size distribution, imaging and obstructing properties of C60 and higher fullerenes formed within arc-grown single walled carbon nanotubes

Abstract The relative size distributions of molecules of C60 and higher fullerenes observed in single walled carbon nanotubes (SWNTs) produced by arc vaporization of carbon in the presence of a mixed Ni/Y catalyst are described. The experimental and calculated imaging properties of the fullerenes, which were observed in ca. 5–10% of SWNTs, are also described. The in situ e-beam irradiation in a 300 kV field emission gun transmission electron microscope causes rapid coalescence of the fullerenes within the SWNTs. The incorporated fullerenes also directly impede crystal growth in SWNTs when their cavities are filled by the liquid phase capillary method.

Two layer 4:4 co-ordinated KI crystals grown within single walled carbon nanotubes

The formation of ‘all surface’ 4:4 co-ordinated KI crystals within 1.4 nm diameter single walled carbon nanotubes (SWNT) is reported. KI was inserted into the SWNTs by a capillary method [J. Sloan, D.M. Wright, H.G. Woo, S. Bailey, G. Brown, A.P.E. York, K.S. Coleman, J.L. Hutchison, M.L.H. Green, J. Chem. Soc. Chem. Commun. (1999) 699], whereby the nanotubes were combined intimately with the molten halide. The crystals grew withh 001 i (relative to bulk KI) parallel to the tubule axes and were continuous tetragonally distorted bilayer crystals composed of alternating columns of K‐I and I‐K pairs when viewed along h 100 i. ” 2000 Elsevier Science B.V. All rights reserved.

Structural changes induced in nanocrystals of binary compounds confined within single walled carbon nanotubes: a brief review

High resolution transmission electron microscopy (HRTEM) studies of single wall carbon nanotubes containing nanocrystals of inorganic salts and other binary compounds show that the confining geometry of the host tubules substantially modifies the local structural and co-ordination properties of the inclusion materials.

Light-induced instability of PbO-filled single-wall carbon nanotubes

We investigated single-wall carbon nanotubes filled with lead oxide, PbO, by transmission electron microscopy and Raman spectroscopy. It is concluded that PbO crystallizes in the orthorombic phase forming nanowires inside the nanotubes. The positions of the PbO Raman lines are downshifted as compared to the bulk material as a result of the reduced dimensionality. As a consequence of the filling, nanotubes become sensitive to the laser irradiation. At higher laser power densities, they oxidize and the free PbO nanowires are left in the sample.

A composite method for the determination of the chirality of single walled carbon nanotubes

An approach to the unambiguous determination of the conformation of individual single walled nanotubes utilizing high‐resolution transmission electron microscopy and digital image processing is described. The exit plane wave of single walled nanotubes restored from a focal series of images is used in a stepwise characterization procedure utilizing both the phase of the real space restoration and its Fourier transform. A combination of these complementary characterization steps yields an accurate measurement of the chiral vector for an individual nanotube.

1D lanthanide halide crystals inserted into single-walled carbon nanotubes

1D crystals of lanthanide halides of the form LnCl3 (Ln = La, Nd, Sm, Eu, Gd, Tb or Yb) have been inserted into single-walled carbon nanotubes (SWNTs) using the molten salt capillary filling method; ca. 20–40% of all the observed SWNTs were filled with melts in the range 650–910 °C with no observable damage to the carbon tubules; high resolution transmission electron microscopy (HRTEM) studies showed that the nanostructures of the encapsulated crystals varied with tubule diameter.

Hydrogen Bonding Networks in Bis(amine)gold(I) Complexes with Disulfonylamide Anions

The use of disulfonylamines as counter-ions allows the synthesis of stable ionic gold(I) complexes with the amine ligands cyclohexylamine, benzylamine, 3-iodobenzylamine, morpholine, pyrrolidine, and piperidine. There is a considerable increase in stability for the morpholine complex compared to the previously synthesised chloro derivative; the benzylamine derivatives displayed better solubility and crystallinity than their chloro analogues. The use of silver disulfonylamine derivatives in the syntheses led in two cases to the incorporation of silver into the products, with concomitantly poor yields. Crystal structure determinations of eight complexes revealed, as expected, extensive systems of N−H···O hydrogen bonds. Amines with NH functions tend to form hydrogen-bonded chain motifs, those with NH2 as donor group form layers of linked ring patterns. It thus seems that the packing can more easily be classified in terms of influence of the cation than of the anion. Some C−H···O hydrogen bonds were also observed, but play a less important role. Aurophilic contacts were not observed, although one mixed gold/silver complex displayed short Au···Ag contacts. Of the two compounds containing iodine, only one showed short I···I contacts.

Electron beam induced in situ clusterisation of 1D ZrCl4 chains within single-walled carbon nanotubes

Cluster formation can be induced in situ in SWNTs filled with ZrCl4 by electron beam irradiation of SWNT/ZrCl4 composites within a field emission gun transmission electron microscope (FEGTEM); the process represents a possible route to the synthesis of 1D-quantum dot arrays formed by related materials.

Correlated transport and high resolution transmission electron microscopy investigations on inorganic-filled single-walled carbon nanotubes showing negative differential resistance

We describe a strategy for fabricating devices on perforated silicon nitride membranes that is ideal for systems with modulated structure, in particular for nanotubes with endohedral inorganic compounds or molecules, or nanotubes externally functionalized with soft materials. It uses dynamic nanostenciling and focussed ion beam while avoiding nanotubes’ exposure to chemicals or beams. Physical properties and high resolution transmission electron microscopy are then correlated. Devices with individual single-walled carbon nanotubes partially filled with potassium iodide (KI) showed negative differential resistance (NDR). We attribute the NDR to electrostatic potential modulation on the nanotube due to permanent dipoles in the KI chain.

The formation of low-dimensional metal trihalide crystals in carbon nanotubes

Molecular dynamics computer simulation models are employed to study the direct filling of single-walled carbon nanotubes (which vary in diameter) with an archetypal metal trihalide, LaCl3. The use of relatively simple potential models allows the investigation of details of both the atomistic filling mechanism and the thermodynamic factors controlling the formation. The resulting low-dimensional crystallites are analysed with respect to bulk crystal structures and compared to experimental high-resolution transmission-electron-microscopy images by simulation of equivalent micrographs from one of the obtained potential models, resulting in excellent agreement between the simulated and experimental images.