Online ISSN
1750-0443
Micro & Nano Letters
Volume 4, Issue 3, September 2009
Volumes & issues:
Volume 4, Issue 3
September 2009
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- Author(s): W.S. Kuo ; T.H. Ko ; H.F. Lu
- Source: Micro & Nano Letters, Volume 4, Issue 3, p. 128 –132
- DOI: 10.1049/mnl.2009.0040
- Type: Article
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p.
128
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The processing and the resulting microstructures of carbon nanotubes (CNTs) grown on graphite nanosheets (GNSs) is examined. The GNSs have a planar shape and are 20–50 nm in thickness. The GNSs were made by the intercalation and exfoliation of natural graphite flakes. Nickel particles serving as the catalyst were distributed on the GNSs. A chemical vapour deposition (CVD) method was used to grow CNTs. Both methane and acetylene were used as the hydrocarbon gases, and the reaction temperatures studied were 700 and 900°C. The distribution of the nickel particles was found critical for the growth of the resulting nano-carbon filaments. Both CNTs and carbon nanofibres (CNFs) were obtained. The nanocarbon filaments vary widely in density, shape and microstructures, dependent on the processing conditions. The microstructure of the joint between the CNT and GNS has been observed by electron microscopy. - Author(s): Q. Zou ; M.Z. Wang ; Y.G. Li ; L.H. Zou ; H. Yu ; Y.C. Zhao
- Source: Micro & Nano Letters, Volume 4, Issue 3, p. 133 –141
- DOI: 10.1049/mnl.2009.0048
- Type: Article
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p.
133
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Various apparatus were used to analyse the structures and the surface states of the nanodiamond particles synthesised by detonation, including a high-resolution transmission electron microscope (HRTEM), an energy diffraction spectrometer (EDS), an X-ray diffractometer (XRD), a Raman spectrometer (Raman), a Fourier transform infrared spectrometer (FTIR) and a differential scanning calorimeter (DSC). The grain size of the nanodiamond particles was in the range of 2–12 nm. However, the average grain size was approximately 5 nm. Moreover, the shapes of the nanodiamond particles were spherical or elliptical. The nanodiamond as-synthesised was very pure, which almost contained carbon only. The contents of the impurity element including O, N and S were very small, which came from the synthesis and purification processes when fabricating the nanodiamond. The surfaces of the nanodiamond particles absorbed many functional groups, such as hydroxy, carbonyl, carboxyl and ether-based resin. The initial oxidation temperature of the nanodiamond powder in air was about 520°C, which was lower than that of the bulk diamond. However, the oxidation temperature of the nanographite existing in the nanodiamond powder was about 228°C. The graphitisation temperature of the nanodiamond in Ar gas was approximately 1305°C. - Author(s): Z. Li and A. Gu
- Source: Micro & Nano Letters, Volume 4, Issue 3, p. 142 –147
- DOI: 10.1049/mnl.2009.0047
- Type: Article
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142
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Spindle-shaped gold nanoparticles were successfully prepared in high yield by a simple wet chemical approach using L-ascorbic acid (AA) as reductant in the presence of cetyltrimethylammonium bromide (CTAB) at room temperature. Transmission electron microscopy, ultraviolet-visible absorption spectroscopy and X-ray diffraction have been used to characterise the obtained products. It is found that the spindle-shaped architecture of gold nanoparticles is drastically influenced by the mass ratio of CTAB/AA, CTAB/HAuCl4, HAuCl4/AA and the concentration of CTAB, AA, HAuCl4. It is revealed that CTAB might play an adsorbent role. - Author(s): K. Rabenorosoa ; C. Clévy ; P. Lutz ; M. Gauthier ; P. Rougeot
- Source: Micro & Nano Letters, Volume 4, Issue 3, p. 148 –154
- DOI: 10.1049/mnl.2009.0034
- Type: Article
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p.
148
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At the microscale, surface forces influence the behaviour of micro-objects more than volumic forces. During micro-assembly processes, contacts occur between a microgripper and a micro-object or between a substrate and a micro-object. The pull-off force, which represents the force required to break a contact, is one of the predominant problems in micro-assembly. Current force measurements are mostly focused on sphere-plane geometries, and models are based on nanoscale theories. The aim of this Letter is to propose an evaluation of the pull-off force for a planar contact, which is the most frequent kind of contact in micro-assembly. Experimental force measurements based on a capacitive microforce sensor and micro/nano robotic systems are carried out. The proposed device enables the study of pull-off forces according to the preload force and the contact angle. Finally, experimental results are discussed and compared with a model. - Author(s): G.J. Qi
- Source: Micro & Nano Letters, Volume 4, Issue 3, p. 155 –159
- DOI: 10.1049/mnl.2009.0055
- Type: Article
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p.
155
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A polymeric precursor, polyhydridomethylsilazane, was pyrolysed in an active ammonia atmosphere at 873 K with subsequent pyrolysis in an inert nitrogen atmosphere at 1873 K, and the polymer-derived ceramic products were studied using a field emission scanning electron microscope, X-ray diffractometer and high-resolution transmission electron microscope. No nanoneedles were observed in the 873 K pyrolysed products, while beta-Si3N4 nanoneedles were obtained after pyrolysis at 1873 K. The as-received nanoneedles were about 100–200 nm in diameter, and the maximum length reached about 10 µm. There were no bulbs or droplets on the tips of the nanoneedles, and no catalysts were used during the pyrolysis of the polymeric precursor. - Author(s): M. Imbaby and K. Jiang
- Source: Micro & Nano Letters, Volume 4, Issue 3, p. 160 –165
- DOI: 10.1049/mnl.2009.0059
- Type: Article
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160
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This Letter presents in detail a new process for the fabrication of 3D stainless steel microcomponents using cold-isopressing techniques. The process starts by producing deep SU-8 master moulds and their negative soft micromoulds in polydimethylsiloxane (PDMS), preparing stainless steel semi-solid paste with high solid loading, filling the soft micromoulds, covering the filled moulds and putting them under hydrostatic pressure. After the pressure is released the green microparts are obtained, de-bound and sintered in vacuum at 1350°C. The resultant microparts show the same quality as the SU-8 master moulds without deformation. The effect of applied hydrostatic pressure on the density of the green and sintered parts as well as the linear shrinkage is discussed in detail. The maximum density of the sintered parts and its corresponding linear shrinkage are found to be 98.6 and 13%, respectively. - Author(s): B. Fallah and C. Falamaki
- Source: Micro & Nano Letters, Volume 4, Issue 3, p. 166 –171
- DOI: 10.1049/mnl.2009.0063
- Type: Article
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p.
166
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A novel method for the production of detached ceramic oxide catalyst nano-particles on ceramic supports is presented. By the addition of a W/O micro-emulsion of colloidal silica to a W/O micro-emulsion of lithium and magnesium nitrate salts, a micro-emulsion of silica aggregates containing detached groups of the ceramic parent salts is prepared. The solid support (porous alpha-alumina) is put into contact with the latter and, after proper heat treatment, nano-sized particles of Li2O/MgO ceramic oxides are formed on separate islands of silica in a detached fashion. The obtained composite shows significant activity for the oxidative coupling of the methane reaction. - Author(s): M.V. Suyetin and A.V. Vakhrushev
- Source: Micro & Nano Letters, Volume 4, Issue 3, p. 172 –176
- DOI: 10.1049/mnl.2009.0031
- Type: Article
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172
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A nanocapsule is investigated for methane storage purposes. The nanocapsule is a ‘bucky shuttle’ (or a nanopeapod) with a hole in its structure. The bucky shuttle has a diameter of a nanotube (10, 10) and is 180 Å in length. A K@C601+ endohedral complex is encapsulated into the nanocapsule. Simulations are performed by a molecular dynamics method. The internal dynamics of the system are investigated – the nanocapsule, the K@C601+ endohedral complex and methane molecules. The closing of the nanocapsule can be induced by the K@C601+ ion transition as a result of applying an electric field. There is no need to keep the electric field at the storage stage, because the K@C601+ ion cannot overcome the hole area owing to the effect of forces created in the hole of the nanocapsule. The opening of the nanocapsule takes place under the heating of the system. It is shown that this is a temperature-sensitive nanocapsule for methane molecule storage under zero external pressure and a temperature of 300 K. The nanocapsule retains 71 methane molecules (3.06 mass%) and releases gas at 350 K. - Author(s): H. Ke ; W. Luo ; G. Cheng ; X. Tian ; Z. Pi
- Source: Micro & Nano Letters, Volume 4, Issue 3, p. 177 –180
- DOI: 10.1049/mnl.2009.0025
- Type: Article
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p.
177
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The flower-like tin disulphide (SnS2) microspheres have been synthesised by a facile solution-based route using polyethylene glycol 200 as the solvent and template. The products are characterised by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Experimental results show that the flower-like SnS2 microspheres with diameters around 2–5 µm are made of many interleaving petal-like nanostructures. These nanopetals are 1–3 µm in side length and less than 60 nm in thickness. The influences of solvent and sulphur source on the morphology of SnS2 nanostructures have also been investigated. The possible growth mechanism is discussed. Furthermore, the room-temperature Raman spectrum of the flower-like SnS2 microspheres is also studied.
Growing carbon nanotubes on graphite nanosheets
Analysis of structures and surface states of the nanodiamond particle synthesised by detonation
Growth of spindle-shaped gold nanoparticles in cetyltrimethylammonium bromide solutions
Measurement of pull-off force for planar contact at the microscale
Beta-Si3N4 nanoneedles in polyhydridomethylsilazane-derived ceramic products by polymeric precursor pyrolysis
Cold-isopress-based process for fabrication of stainless steel micromachine components
Use of nano-silica carriers for the fabrication of Li2O/MgO catalyst nano-particles on the surface of alpha-alumina supports
Temperature-sensitive nanocapsules for methane storage
Synthesis of flower-like SnS2 nanostructured microspheres using PEG 200 as solvent
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