Mechanics of filled carbon nanotubes (original) (raw)
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Recent developments in inorganically filled carbon nanotubes: successes and challenges
Science and Technology of Advanced Materials, 2010
Carbon nanotubes (CNTs) are a unique class of nanomaterials that can be imagined as rolled graphene sheets. The inner hollow of a CNT provides an extremely small, one-dimensional space for storage of materials. In the last decade, enormous effort has been spent to produce filled CNTs that combine the properties of both the host CNT and the guest filling material. CNTs filled with various inorganic materials such as metals, alloys, semiconductors and insulators have been obtained using different synthesis approaches including capillary filling and chemical vapor deposition. Recently, several potential applications have emerged for these materials, such as the measurement of temperature at the nanoscale, nano-spot welding, and the storage and delivery of extremely small quantities of materials. A clear distinction between this class of materials and other nanostructures is the existence of an enormous interfacial area between the CNT and the filling matter. Theoretical investigations have shown that the lattice mismatch and strong exchange interaction of CNTs with the guest material across the interface should result in reordering of the guest crystal structure and passivation of the surface dangling bonds and thus yielding new and interesting physical properties. Despite preliminary successes, there remain many challenges in realizing applications of CNTs filled with inorganic materials, such as a comprehensive understanding of their growth and physical properties and control of their structural parameters. In this article, we overview research on filled CNT nanomaterials with special emphasis on recent progress and key achievements. We also discuss the future scope and the key challenges emerging out of a decade of intensive research on these fascinating materials.
Synthesis and properties of filled carbon nanotubes
Diamond and Related Materials, 2003
Single-and multi-walled carbon nanotubes are very interesting nanoscaled materials with many possible applications in nanoelectronics. Especially, nanotubes filled with ferromagnetic materials (Fe, Co, Ni) may have significant potential in data storage. Such structures may help to exceed the best available storage densities ()65 Gbyinch ) and show in the case of Fe-2 filled nanotubes higher coercivities compared to bulk Fe. In addition, metal-filled carbon nanotubes are promising nanowires with excellent oxidation protection. In this paper we describe the synthesis of Fe-, Ni-and Co-filled carbon nanotubes by using the chemical vapor deposition method. Varying the deposition conditions we have obtained filled nanotubes with relatively uniform core diameters and different thicknesses of the carbon walls. The core diameters vary between 15 and 30 nm and the thickness of the carbon shells between 2 and 60 nm. The length of the tubes amounts up to 30 mm. The filled carbon nanotubes are characterised by scanning and transmission electron microscopy and energy dispersive X-ray analysis. The magnetic behaviour of the aligned Fe-filled tubes is investigated using alternating gradient magnetometry measurements and electron holography. The hysteresis loops indicate a magnetic anisotropy. The coercivity depends on the direction of the applied magnetic field. The observed enhanced coercivities are significantly higher than in bulk Fe. ᮊ
Carbon Nanotubes and Related Structures: New Materials for the Twenty-First Century
American Journal of Physics, 2004
Introduction 1.1 The discovery of fullerene-related carbon nanotubes 1.2 Characteristics of multiwalled nanotubes 1.3 Single-walled nanotubes 1.4 Pre-1991 evidence for carbon nanotubes 1.5 Nanotube research 1.6 Organisation of the book References 2 Synthesis: Preparation methods, growth mechanisms and processing techniques 2.1 Production of multiwalled nanotubes: non-catalytic methods 2.1.1 The arc-evaporation technique 2.1.2 The quality of nanotube samples produced by arc-evaporation 2.1.3 Safety considerations 2.1.4 Condensation of carbon vapour in the absence of an electric field 2.1.5 Pyrolytic methods 2.1.6 Electrochemical synthesis of nanotubes 2.2 Experiments on the heat treatment of fullerene soot 2.3 Catalytically produced multiwalled nanotubes 2.3.1 Background 2.3.2 Growth mechanisms of catalytically produced nanotubes 2.3.3 Synthesis of aligned nanotubes by catalysis vii 2.4 Nanotubes on TEM support grids: a word of warning 2.5 Single-walled nanotubes 2.5.1 Discovery 2.5.2 Subsequent work on single-walled tubes 2.5.3 Nanotube 'ropes' 2.6 Theories of nanotube growth 2.6.1 General comments 2.6.2 Why do tubes remain open during growth? 2.6.3 Properties of the arc plasma 2.6.4 An alternative model 2.6.5 Growth of single-walled nanotubes 2.7 Purification of multiwalled tubes 2.8 Purification of single-walled tubes 2.9 Alignment of nanotube samples 2.10 Length control of carbon nanotubes 2.11 Discussion References 3 Structure 3.1 Classification of tubular biological structures 3.2 Bonding in carbon materials 3.3 The structure of carbon nanotubes: theoretical discussion 3.3.1 Vector notation for carbon nanotubes 3.3.2 Unit cells of nanotubes 3.3.3 Multiwalled nanotubes 3.3.4 Theory of nanotube capping 3.3.5 Symmetry classification of nanotubes 3.3.6 Elbow connections, tori and coils 3.3.7 Arrays of single-walled nanotubes 3.4 The physical stability of carbon nanotubes 3.5 Experimental studies of nanotube structure: multiwalled nanotubes 3.5.1 Techniques 3.5.2 The layer structure: experimental observations 3.5.3 The layer structure: models 3.5.4 Electron diffraction 3.5.5 Plan-view imaging by HREM 3.5.6 The cross-sectional shape of multiwalled nanotubes 3.5.7 HREM studies of cap structure 3.5.8 Elbow connections and branching structures viii Contents 3.6 Experimental studies of nanotube structure: single-walled nanotubes 3.6.1 High resolution electron microscopy and electron diffraction 3.6.2 Scanning probe microscopy 3.6.3 Nanotube hoops and diameter doubling 3.7 Structure of carbon nanoparticles 3.8 Nanocones 3.9 Discussion References 4 The physics of nanotubes 4.1 Electronic properties of graphite and carbon fibres 4.1.1 Band structure of graphite 4.1.2 Transport properties of graphite, disordered carbons and carbon fibres 4.1.3 Magnetoresistance of graphite and carbon fibres 4.2 Electronic properties of nanotubes: theory 4.2.1 Band structure of single-walled tubes 4.2.2 Band structure of multiwalled tubes 4.2.3 Electron transport in nanotubes 4.2.4 Nanotube junctions 4.2.5 Electronic properties of nanotubes in a magnetic field 4.3 Electronic properties of nanotubes: experimental measurements 4.3.1 Resistivity measurements on multiwalled nanotubes 4.3.2 Resistivity measurements on single-walled nanotubes 4.3.3 Doping of nanotube bundles 4.3.4 Electron spin resonance 4.4 Magnetic properties of nanotubes 4.5 Optical properties of nanotubes 4.6 Vibrational properties of nanotubes 4.6.1 Symmetry of vibrational modes 4.6.2 Experimental IR and Raman spectra: multiwalled nanotubes 4.6.3 Experimental IR and Raman spectra: single-walled nanotubes 4.7 Electron energy loss spectroscopy of nanotubes 4.8 Nanotube field emitters 4.9 Discussion References ix Contents 5 Nanocapsules and nanotest-tubes 5.1 Metallofullerenes 5.2 Filling nanotubes and nanoparticles by arc-evaporation 5.2.1 Early work 5.2.2 Further studies 5.3 Preparation of filled nanoparticles from microporous carbon 5.4 Properties of filled nanoparticles 5.4.1 Protection from environmental degradation 5.4.2 Encapsulation of magnetic materials 5.4.3 Encapsulation of radioactive materials 5.5 Technegas 5.6 Opening and filling of nanotubes using chemical methods and capillarity 5.6.1 The work of Ajayan and Iijima 5.6.2 Selective opening using gas-phase oxidants 5.6.3 Opening by treatment with nitric acid 5.6.4 Alternative liquid-phase oxidants 5.6.5 Filling with molten materials 5.6.6 Experiments on capillarity and wetting 5.6.7 Chemistry and crystallisation in nanotubes 5.6.8 Biological molecules in nanotubes 5.7 Filling of single-walled nanotubes 5.8 Storing gases in nanotubes 5.9 Discussion References 6 The ultimate carbon fibre? The mechanical properties of carbon nanotubes 6.1 Conventional carbon fibres 6.2 Graphite whiskers 6.3 Catalytically grown carbon fibres 6.4 Mechanical properties of carbon nanotubes 6.4.1 Theoretical predictions 6.4.2 Experimental observations using TEM: qualitative 6.4.3 Experimental observations using TEM: quantitative 6.4.4 Experimental observations using scanning probe microscopy 6.5 Carbon nanotube composites 6.5.1 Introduction 6.5.2 Bonding between nanotubes and matrix x Contents 6.5.3 Aspect ratio 6.5.4 Experiments on incorporating nanotubes into a matrix 6.5.5 Applications of nanotube-containing composites 6.6 Nanotubes as tips for scanning probe microscopes 6.7 Discussion References 7 Curved crystals, inorganic fullerenes and nanorods 7.1 Chrysotile and imogolite 7.2 Inorganic fullerenes from layered metal dichalcogenides 7.2.1 Synthesis of chalcogenide fullerenes 7.2.2 Structure of chalcogenide fullerenes 7.2.3 Inorganic fullerenes as solid-state lubricants 7.3 Nanotubes and nanoparticles containing boron and nitrogen 7.3.1 Boron-carbon-nitride tubes 7.3.2 Pure boron nitride tubes and nanoparticles 7.3.3 Structure of boron nitride tubes and nanoparticles 7.4 Carbide nanorods 7.5 Discussion References 8 Carbon onions and spheroidal carbon 8.1 Carbon onions 8.1.1 Discovery 8.1.2 Ugarte's experiments: irradiation of cathodic soot 8.1.3 Production of onions from other carbons 8.1.4 The structure of carbon onions 8.1.5 Formation mechanism of carbon onions 8.1.6 Stability of carbon onions 8.1.7 Bulk synthesis of carbon onions 8.1.8 The formation of diamond inside carbon onions 8.2 Spheroidal carbon particles in soot 8.2.1 Background 8.2.2 Growth mechanisms: the traditional view 8.2.3 The icospiral growth mechanism 8.2.4 The structure of carbon black 8.3 Spherulitic graphite cast iron 8.3.1 History 8.3.2 The structure of spherulitic graphite 8.3.3 The precipitation process xi Contents 8.4 Spheroidal structures in mesophase pitch 8.5 Discussion References 9 Future directions 9.1 Towards a carbon nanotube chemistry 9.2 New all-carbon structures 9.3 Nanotubes in nanotechnology 9.4 Final thoughts References Name index Subject index xii Contents
Effect of crystalline filling on the mechanical response of carbon nanotubes
Carbon, 2009
The electrical and mechanical properties of the same hybrid carbon nanotube before and after removal of the core Ga-doped ZnS semiconductor filling have been analysed inside a transmission electron microscope (TEM) using a conductive atomic force microscope-TEM system. It is found that the encapsulated material can substantially change the mechanical response of the turbostratic carbon tube container. Furthermore, because the extent of filling is operator-controlled, this provides a simple way to change on-demand the stiffness of hybrid carbon nanotubes.
Emerging Materials Research, 2013
Carbon nanotubes (CNT) are nature’s finest gift to mankind, the most amazing and wonderful nanostructure that the human being has discovered so far. CNT are either single walled or multiwalled and have been studied extensively. A large number of research articles, review articles and books have been published on this topic. However, review articles covering all the aspects of CNT are rarely found. This article gives an overview of CNT in terms of classification, synthesis, characterization, functionalization, properties, composites, applications and future directions.
Controlled filling and external cleaning of multi-wall carbon nanotubes using a wet chemical method
Carbon, 2007
A controlled, material-independent and adaptable cold wet chemical procedure is described. It allows organic and inorganic compounds to be confined inside multi-wall carbon nanotubes. The procedure mainly consists of a lyophilization process to fill multi-wall carbon nanotubes (MWCNTs), and a washing method to clean their outer surface without removing the encapsulated material. The technique was tested by synthesizing CdS crystals inside the nanotubes. Morphological and structural studies of the CdS crystals demonstrated a complete control of the synthesis process, and the possibility of maximizing the crystal size and the filling efficiency that approached 70% of open-ended nanotubes.