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1.
Dispersion and alignment of carbon nanotubes in polycarbonate 总被引:2,自引:0,他引:2
M. Sennett E. Welsh J.B. Wright W.Z. Li J.G. Wen Z.F. Ren 《Applied Physics A: Materials Science & Processing》2003,76(1):111-113
Dispersion and alignment of carbon nanotubes in thermoplastic polymers such as polycarbonate have been studied. Dispersion
was accomplished by mixing in a conical twin-screw extruder and alignment was carried out using a fiber-spinning apparatus.
The effects of mixing time and fiber draw rates on dispersion and alignment were investigated. Uniform dispersions were produced
with relatively short residence times in the extruder. Excellent alignment of carbon nanotubes in nanocomposite filaments
was obtained when the fiber draw rate was greater than 70 m/min. The ability to closely control the dispersion and alignment
of carbon nanotubes in polymers is expected to lead to the development of nanocomposites with desirable electronic and structural
properties.
Received: 7 January 2002 / Accepted: 11 April 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +1-508/233-5521, E-mail: Michael.Sennett@natick.army.mil 相似文献
2.
Y. Chen M.J. Conway J.D. Fitzgerald 《Applied Physics A: Materials Science & Processing》2003,76(4):633-636
Multi-walled carbon nanotubes with cylindrical and bamboo-type structures are produced in a graphite sample after mechanical
milling at ambient temperature and subsequent thermal annealing up to 1400 °C. The ball milling produces a precursor structure
and the thermal annealing activates the nanotube growth. Different nanotubular structures indicate different formation mechanisms:
multi-wall cylindrical carbon nanotubes are probably formed upon micropores and the bamboo tubes are produced because of the
metal catalysts. A two-dimensional growth governed by surface diffusion is believed to be one important factor for the nanotube
growth. A potential industrial production method is demonstrated with advantages of large production quantity and low cost.
Received: 17 May 2002 / Accepted: 12 September 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +61-2/6125-8338, E-mail: ying.chen@anu.edu.au 相似文献
3.
G. Brown S.R. Bailey M. Novotny R. Carter E. Flahaut K.S. Coleman J.L. Hutchison M.L.H. Green J. Sloan 《Applied Physics A: Materials Science & Processing》2003,76(4):457-462
We describe here the high yield filling (i.e. >50%) of single walled nanotubes (SWNTs) with a variety of halides, achieved
according to various modified filling procedures. Both bundles and discrete SWNTs can be filled continuously up to lengths
of several hundred nm, often with filling yields approaching 60–70% or better. In addition some high yield filled SWNTs were
subjected to long-term washing in either boiling or room temperature. aqueous media, which does not remove the filling from
the tubules, but enables effective removal of water-soluble extraneous materials .
Received: 10 May 2002 / Accepted: 25 October 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +44-1865/272-690, E-mail: jeremy.sloan@chem.ox.ac.uk 相似文献
4.
Field emission from single-walled carbon nanotubes (SWNTs) aligned on a patterned gold surface is reported. The SWNT emitters
were prepared at room temperature by a self-assembly monolayer technique. SWNTs were cut into sub-micron lengths by sonication
in an acidic solution. Cut SWNTs were attached to the gold surface by the reaction between the thiol groups and the gold surface.
The field-emission measurements showed that the turn-on field was 4.8 V/μm at an emission current density of 10 μA/cm2. The current density was 0.5 mA/cm2 at 6.6 V/μm. This approach provides a novel route for fabricating CNT-based field-emission displays.
Received: 3 May 2002 / Accepted: 6 May 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +82-54/279-8298, E-mail: ce20047@postech.ac.kr 相似文献
5.
Nanotube growth during annealing of mechanically milled Boron 总被引:1,自引:0,他引:1
J.D. Fitz Gerald Y. Chen M.J. Conway 《Applied Physics A: Materials Science & Processing》2003,76(1):107-110
Boron powder, finely ground in a tungsten carbide ball mill in an ammonia atmosphere, has been annealed at 1200 °C in flowing
nitrogen to produce small quantities of cylindrical BN nanotubes, both as isolated individuals and grouped into ropes. Thick-walled
conical BN tubes are abundant in specimens annealed for longer times, and their growth was catalysed once WC debris was converted
into W metal particles. Some catalytic effect of small W nanoparticles could be necessary for nanotube formation, though no
tip particles have been imaged here. Given the low temperature of mechanical milling and annealing, BN growth must involve
surface diffusion and solid-state reconfiguration. It could be possible to engineer desirable physical and chemical properties
by exploiting the variation in cylindrical versus conical BN structures as a function of annealing time.
Received: 19 December 2001 / Accepted: 3 April 2002 / Published online: 19 July 2002
RID="*"
ID="*"Corresponding author. Fax: +61-2/6125-8253, E-mail: john.fitzgerald@anu.edu.au 相似文献
6.
C.L. Wang S.Z. Lin Y. Niu W.T. Wu Z.L. Zhao 《Applied Physics A: Materials Science & Processing》2003,76(2):157-163
A bulk nanocrystallined Ag50Ni alloy has been prepared by hot-pressing the mechanically pre-alloyed powders at 620 °C under
a normal pressure of 58 MPa in vacuum. The microstructural characteristics of the alloy were studied by X-ray diffraction
(XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results of the precise determination
of the lattice parameters of the phases in the powders and in the alloy by XRD show that, after mechanical alloying for 200 h,
the solid solubility of Ag in Ni reaches 4.85±0.21 at %, while that of Ni in Ag reaches 0.84±0.30 at %. After hot pressing,
the Ag- and Ni-rich phases in the alloy still show a certain degree of supersaturation, with a solid solubility of 0.45±0.11 at %
of Ag in Ni. After further annealing of the alloy at 700 °C for 24 h, the solubility decreases to a value of 0.21±0.11 at %
for Ag in Ni and to less than 0.1 at % for Ni in Ag. The grain size of the mechanically alloyed powders was of ca 6 nm. After
hot pressing, the grain size of the alloy increased to 40–60 nm and then grew further to 100–110 nm after annealing. The influence
of the variation of the grain size and the internal stress on the line breadth of the X-ray diffraction peaks has been evaluated
in detail. Finally, the role of the nanocrystalline structure in the fast densification process of the powders is also discussed.
Received: 12 September 2001 / Accepted: 18 Febraury 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +86-24/2389-3624, E-mail: wwt@icpm.syb.ac.cn 相似文献
7.
S.-H. Jung M.-R. Kim S.-H. Jeong S.-U. Kim O.-J. Lee K.-H. Lee J.-H. Suh C.-K. Park 《Applied Physics A: Materials Science & Processing》2003,76(2):285-286
Synthesis of multi-walled carbon nanotubes (MWNTs) by arc discharge in liquid nitrogen is reported. As liquid nitrogen substituted
both vacuum and cooling systems, high-quality MWNTs were produced at a low cost. The content of the MWNTs can be as high as
70% of the reaction product. Auger-spectroscopy analysis revealed that no nitrogen is incorporated in the MWNTs. This method
can be an economical route for the mass production of highly crystalline MWNTs.
Received: 5 July 2002 / Accepted: 8 July 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +82-54/279-8298, E-mail: ce20047@postech.ac.kr 相似文献
8.
R.L.D. Whitby W.K. Hsu C.B. Boothroyd K.S. Brigatti H.W. Kroto D.R.M. Walton 《Applied Physics A: Materials Science & Processing》2003,76(4):527-532
Time-dependent powder X-ray-diffraction analyses reveal that the conversion of WO3 into WS2 on carbon nanotube surfaces in the presence of H2S is a one-step process. The WS2 layers grow simultaneously along the tube in the radial and axial directions.
Received: 17 June 2002 / Accepted: 19 June 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +44-1273/677-196, E-mail: d.walton@sussex.ac.uk 相似文献
9.
W. Wang Z. Liu Y. Liu C. Xu C. Zheng G. Wang 《Applied Physics A: Materials Science & Processing》2003,76(3):417-420
Using a simple wet-chemical route, we synthesized CuO nanorods with diameters of ca. 5–15 nm and lengths of up to 400 nm.
The purity, crystallinity, morphology, structure features, and chemical composition of the as-prepared CuO nanorods were investigated
by powder X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron
spectroscopy, and Raman spectroscopy.
Received: 22 March 2002 / Accepted: 12 June 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: wangqun@nju.edu.cn 相似文献
10.
High-resolution electron microscopy of individual metallofullerene molecules on the dipole orientations in peapods 总被引:1,自引:0,他引:1
K. Suenaga T. Okazaki K. Hirahara S. Bandow H. Kato A. Taninaka H. Shinohara S. Iijima 《Applied Physics A: Materials Science & Processing》2003,76(4):445-447
Electron microscopy with atomic sensitivity enables us to obtain a direct image of the intra-molecular structure of metallofullerenes
encapsulated inside single-walled carbon nanotubes. By a comparison of high-resolution images with a simulation to extract
the relative atom positions for encaged metal atoms in each molecule, the distribution of the molecular orientations and interactions
between adjacent molecules in metallofullerene peapods have been statistically analyzed. The results are suggestive of strong
interactions between fullerene–fullerene and fullerene–tube in peapods at room temperature.
Received: 10 October 2002 / Accepted: 25 October 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/61-6310, E-mail: suenaga-kazu@aist.go.jp 相似文献
11.
Giant field amplification in tungsten nanowires 总被引:5,自引:0,他引:5
Umnov A.G. Shiratori Y. Hiraoka H. 《Applied Physics A: Materials Science & Processing》2003,77(1):159-161
The original RF-sputtering-assisted technique to produce metal wires with tip-curvature radii at the nanometer scale was developed
and applied to tungsten. The wire tips were characterized by scanning electron microscopy. Field-emission tests of those wires
exhibit excellent performance and reliable processability. Very high field-amplification factors of 18000 were demonstrated.
Received: 1 November 2002 / Accepted: 30 November 2002 / Published online: 11 April 2003
RID="*"
ID="*"Corresponding author. Fax: +1-972/479-4482, E-mail: alexander.umnov@fla.fujitsu.com 相似文献
12.
13.
β-Ga2O3 nanowires have been synthesized using Ga metal and H2O vapor at 800 °C in the presence of Ni catalyst on the substrate. Remarkable reduction of the diameter and increase of the
length of the Ga2O3 nanowires are achieved by separation of Ga metal and H2O vapor before they reach the substrate. Transmission electron microscopy analyses indicate that the β-Ga2O3 nanowires possess a single-crystalline structure. Photoluminescence measurements show two broad emission bands centered at
290 nm and 390 nm at room temperature.
Received: 27 June 2002 / Accepted: 7 October 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +886-6/234-4496, E-mail: wujj@mail.ncku.edu.tw 相似文献
14.
Z. Siwy D. Dobrev R. Neumann C. Trautmann K. Voss 《Applied Physics A: Materials Science & Processing》2003,76(5):781-785
For the preparation of a single asymmetrically shaped nanopore in a polyimide membrane, Kapton foils were irradiated with
single heavy ions and subsequently etched from one side in sodium hypochlorite (NaOCl). The other side of the membrane was
protected from etching by a stopping medium containing a reducing agent for hypochlorite ions (OCl-). The resulting conical nanopore rectified ion current and exhibited a stable ion-current flow.
Received: 23 May 2002 / Accepted: 2 September 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +49-6159/712-179, E-mail: Z.Siwy@gsi.de 相似文献
15.
Z.P. Huang D.Z. Wang J.G. Wen M. Sennett H. Gibson Z.F. Ren 《Applied Physics A: Materials Science & Processing》2002,74(3):387-391
The effect of pure nickel, iron and cobalt on growth of aligned carbon nanotubes was systematically studied by plasma-enhanced
hot-filament chemical vapor deposition. It is found that the catalyst has a strong effect on the nanotube diameter, growth
rate, wall thickness, morphology and microstructure. Ni yields the highest growth rate, largest diameter and thickest wall,
whereas Co results in the lowest growth rate, smallest diameter and thinnest wall. The carbon nanotubes catalyzed by Ni have
the best alignment and the smoothest and cleanest wall surface, whereas those from Co are covered with amorphous carbon and
nanoparticles on the outer surface. The carbon nanotubes produced from Ni catalyst also exhibit a reasonably good graphitization.
Therefore, Ni is considered as the most suitable catalyst for growth of aligned carbon nanotubes.
Received: 30 November 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002 相似文献
16.
Electrochemical synthesis of ordered CdTe nanowire arrays 总被引:1,自引:0,他引:1
A.W. Zhao G.W. Meng L.D. Zhang T. Gao S.H. Sun Y.T. Pang 《Applied Physics A: Materials Science & Processing》2003,76(4):537-539
Semiconductor CdTe nanowire arrays embedded in the nanochannels of the porous anodic alumina (PAA) template have been prepared
by using a potentiostatic electrochemical deposition method. The morphology and structure of the CdTe nanowire arrays have
been characterized by X-ray powder diffraction, transmission electron microscopy, and high-resolution transmission electron
microscopy. It is found that the CdTe nanowires with diameters and lengths of about 60 nm are single-crystalline with cubic
phase structure, uniformly and continuously embedded in the nanochannels of the PAA template. X-ray energy-dispersion analysis
and X-ray photoelectron spectroscopy analysis indicate that stoichiometric CdTe was formed. The growth mechanism of the CdTe
nanowires is also discussed.
Received: 11 June 2002 / Accepted: 2 July 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +86-551/559-1434, E-mail: aiwuzhao@yahoo.com.cn 相似文献
17.
Boron nitride (BN) nanotubes have been synthesized by evaporating a mixture of boron and gallium oxide in the presence of
ammonia gas. The synthesized BN nanotubes exhibit a well-crystallized concentric structure with diameters less than 30 nm,
and no carbon contamination or defects could be observed, while the BN nanotubes with large diameters usually show a number
of defects. Some BN nanohorn structures could also be observed in the product. The carbon-free growth of BN nanotubes was
explained based on the vapor–liquid–solid growth mechanism, and the catalytic activity of liquid gallium for BN one-dimensional
growth was also demonstrated.
Received: 16 April 2002 / Accepted: 25 May 2002 / Published online: 19 July 2002 相似文献
18.
J.H. Liao K.J. Chen L.N. Xu C.W. Ge J. Wang L. Huang N. Gu 《Applied Physics A: Materials Science & Processing》2003,76(4):541-543
The one-dimensional coagulation of gold colloidal particles dispersed in organic solvent was investigated with transmission
electron microscopy. The results indicate that the length of the nanoparticle chains can be modulated by changing the concentration
of the solutions. It was also demonstrated that the wetting of the substrate surface hardly influenced the morphology of the
nanoparticle chains, which revealed that the particle chains had been formed in the solution before deposition on the substrates.
A general theoretical interpretation is provided to explain the linear coagulation of gold colloidal particles, on the basis
of the asymmetrical distribution of the charges absorbed on the surface of the gold colloidal particles, as well as the action
of the solvent molecules.
Received: 8 April 2002 / Accepted: 1 July 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +86-025/361-9983, E-mail: jhliao@seu.edu.cn 相似文献
19.
Growth of vertically aligned carbon-nanotube array on large area of quartz plates by chemical vapor deposition 总被引:3,自引:0,他引:3
W.D. Zhang Y. Wen W.C. Tjiu G.Q. Xu L.M. Gan 《Applied Physics A: Materials Science & Processing》2002,74(3):419-422
A simple method has been developed for growth of well-aligned carbon nanotubes (CNTs) on nickel-film quartz plates by chemical
vapor deposition (CVD) with organic ethylenediamine as a precursor. High-density carbon nanotubes were vertically aligned
on a large area of the quartz plates. The height of the nanotube array could be controlled by varying the CVD time. High-resolution
transmission electron microscopy analysis revealed that the multiwalled CNTs were composed of crystalline graphitic sheets
with a bamboo structure.
Received: 28 May 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002 相似文献
20.
Manganese oxide (hausmannite) nanowires were prepared by annealing precursor powders at a temperature of 800 °C for 3 h, which
were produced in a novel inverse microemulsion (IμE) system. The microstructures of the as-prepared Mn3O4 nanowires were investigated by means of X-ray diffraction, transmission electron microscopy, and Raman spectra. It has been
found that the Mn3O4 nanowires were relatively straight and their surfaces were smooth with a typical diameter of 75–150 nm. The formation mechanism
of the Mn3O4 nanowires is discussed.
Received: 30 May 2002 / Accepted: 7 October 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: wangqun@nju.edu.cn 相似文献