共查询到20条相似文献,搜索用时 31 毫秒
1.
Ali Khademi Rouhollah Azimirad Yung-Tang Nien Alireza Z. Moshfegh 《Journal of nanoparticle research》2011,13(1):115-125
The field-emission properties of molybdenum oxide nanowires grown on a silicon substrate and its emission performance in various
vacuum gaps are reported in this article. A new kind of molybdenum oxides named nanowires with nanoscale protrusions on their
surfaces were grown by thermal vapor deposition with a length of ~1 μm and an average diameter of ~50 nm. The morphology,
structure, composition and chemical states of the prepared nanostructures were characterized by scanning electron microscopy
(SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy
(XPS). According to XRD, XPS, and TEM analyses, the synthesized samples were composed of MoO2 nanowires formed over a thin layer of crystalline Mo4O11. TEM observation revealed that these nanowires have some nanoscale protrusion on their surface. These nanoprotrusions resulted
in enhancement of field-emission properties of nanowires comprising nanoprotrusions. The turn-on emission field and the enhancement
factor of this type of nanostructures were measured 0.2 V/μm and 42991 at the vacuum gap of 300 μm, respectively. These excellent
emission properties are attributed to the special structure of the nanowires that have potential for utilizing in vacuum nanoelectronic
and microelectronic applications. 相似文献
2.
Ram Manohar Yadav Dinesh Pratap Singh T. Shripathi O. N. Srivastava 《Journal of nanoparticle research》2008,10(8):1349-1354
We report the observations made on the synthesis and characterization of C–N nanotube blocks and Y-junctions in bamboo-like
C–N nanotubes. The C–N nanotube Blocks have been synthesized by pyrolyzing the mixture of silver nitrate acetonitrile solution
and ferrocene benzene solution. The structural/microstructural characterization of the as-synthesized material has been done
using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopic (XPS)
analysis has been carried out to confirm the presence of nitrogen in nanotubes. These investigations reveal the formation
of blocks of bamboo-like nanotubes having the dimension 300 × 200 × 30 μm and the diameter is 20–50 nm. We also observe the
formation of Y-junctions in bamboo-like nanotubes as we spray the acetonitrile ferrocene and AgNO3 mixture. The length of the synthesized Y-junction nanotube bundles is ~2 μm. Some more complex Ψ-shaped junctions are also
found to be present. The diameters of the Y-junction nanotubes is ~80 nm at the junction and 25–50 nm at the branches. 相似文献
3.
F. Kokai K. Uchiyama T. Shimazu A. Koshio 《Applied Physics A: Materials Science & Processing》2010,101(3):497-502
Two types of one-dimensional (1D) nanostructures—amorphous silicon carbide (SiC) nanowires, 5–30 nm thick and 0.5–2 μm long,
and carbon nanotubes (CNTs) filled completely with crystalline SiC nanowires, 10–60 nm thick and 2–20 μm long—were synthesized
by the laser ablation of carbon-silicon targets in the presence of high-pressure Ar gas up to 0.9 MPa. All the CNTs checked
by transmission electron microscopy contained SiC, and no unfilled CNTs were produced. We discuss the growth of the two nanostructures
based on the formation of molten Si–C composite particles and their instabilities leading to the precipitation of Si and C. 相似文献
4.
Harsimran Kaur Archana Chaudhary Inderpreet Kaur Kashmir Singh Lalit M. Bharadwaj 《Journal of nanoparticle research》2011,13(6):2295-2303
Nanotechnology is playing an important role in drug delivery to overcome limitations of conventional drug delivery systems
in terms of solubility, in vivo stability, pharmacokinetics, and bio-distribution. The controlled transportation of drug into
the cell and within the cell is a major challenge to be addressed. Cellular molecular motors have been exploited for their
cargo carrying capacity for various applications including engineering and health care. Combination of nanotechnology and
biomolecular motors can address some of the challenges in drug delivery. In the present study, transportation of drug nanocomposites
has been demonstrated. Nanocomposites of 6-mercaptopurine and levodopa drugs (cancer and Parkinson’s disease, respectively)
were prepared with gold nanoparticles (GNPs) by covalent attachment and these nanocomposites were attached to actin filaments.
These nanocomposites were in-turn transported by actin filaments on myosin tracks. Characterization of drug nanocomposites
formation was done by UV–Vis spectroscopy, field emission scanning electron microscopy, transmission electron microscopy,
and confocal microscopy. GNP composites of 6-mercaptopurine and levodopa were formed by sulfide and amide bond formation,
respectively. Average velocity of actin filament attached to nanocomposites was found to be 3.17 and 3.89 μm/s for levodopa
and 6-mercaptopurine, respectively, as compared to actin filaments with velocity of 4.0–6.0 μm/s. Three concepts have been
proposed for the study of drug transportation into the cell based on polycationic complex formation, interaction of actin
with cellular myosin and Biomolecular Adaptor for Retrograde Transport (BART) technology. The aspects of this study heads
toward the development of an approach to utilize molecular motors for nanoscale transportation endogenously. 相似文献
5.
Hak-Sung Kim Sanjay R. Dhage Dong-Eun Shim H. Thomas Hahn 《Applied Physics A: Materials Science & Processing》2009,97(4):791-798
An intense pulsed light (IPL) from a xenon flash lamp was used to sinter copper nanoink printed on low-temperature polymer
substrates at room temperature in ambient condition. The IPL can sinter the copper nanoink without damaging the polymer substrates
in extremely short time (2 ms). The microstructure of the sintered copper film was investigated using X-ray powder diffraction
(XRD), optical microscopy, scanning electron microscopy (SEM), X-ray micro tomography, and atomic force microscopy (AFM).
The sintered copper film has a grainy structure with neck-like junctions. The resulting resistivity was 5 μΩ cm of electrical
resistivity which is only 3 times as high as that of bulk copper. The IPL sintering technique allows copper nanoparticles
to be used in inkjet printing on low-temperature substrates such as polymers in ambient conditions. 相似文献
6.
A. G. Leyva M. Granada D. F. Rodriguez H. E. Troiani 《Journal of nanoparticle research》2011,13(10):5129-5134
Uniform polycrystalline SnO2 microtubes formed by sintered nanoparticles (fixed to a surface or in free standing form) were obtained with the infiltration
technique using SnCl4 as precursor and a porous polycarbonate (PC) film as template. The advantage of this synthesis method was based on its simplicity,
reproducibility, low cost, and the possible applicability to other complex oxides. The morphology and crystal structure of
SnO2 tubes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction
(XRD). The crystalline sizes of the nanoparticles assembled in the tube walls obtained at 600 °C were in the range of 5–7 nm,
calculated from both the XRD and the TEM data. The length of the microtubes fixed to a silicon nitride surface ranged between
2 and 7 μm. Sensors fabricated with this material showed unusual sensitivity to ethanol at room temperature and fast reversible
response, as compared to those obtained by the deposition of metallic tin film and further oxidation (Rheotaxial Growth and
Thermal Oxidation method). 相似文献
7.
Wee Ong Siew Seong Shan Yap Cécile Ladam Øystein Dahl Turid Worren Reenaas Teck Yong Tou 《Applied Physics A: Materials Science & Processing》2011,104(3):877-881
Nanosecond-pulsed KrF (248 nm, 25 ns) and Nd:YAG (1064 nm, 532 nm, 355 nm, 5 ns) lasers were used to ablate a polycrystalline
Si target in a background pressure of <10−4 Pa. Si films were deposited on Si and GaAs substrates at room temperature. The surface morphology of the films was characterized
using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Round droplets from 20 nm to 5 μm were detected
on the deposited films. Raman Spectroscopy indicated that the micron-sized droplets were crystalline and the films were amorphous.
The dependence of the properties of the films on laser wavelengths and fluence is discussed. 相似文献
8.
D. A. Romanov E. A. Budovskikh V. E. Gromov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(6):1112-1117
The surface topography and structure of copper layers exposed to multiphase plasma jets of products of electrical explosion
of molybdenum and copper foils are studied using profilometry and scanning electron and light microscopy. Such treatment allows
deposition of either layered coatings or alloyed composite layers. It is found that the surface layer roughness parameter
is R
a
= 3.2−4.0 μm. The thickness of some copper and molybdenum layers of coatings is 15–20 μm. Electroexplosive alloying produces
layers 25 μm thick. Sizes of copper inclusions in the molybdenum matrix near the surface of such layers vary from 30 nm to
1–2 μm. 相似文献
9.
Y. C. Guan W. Zhou H. Y. Zheng Z. L. Li 《Applied Physics A: Materials Science & Processing》2010,101(2):339-344
The solidification microstructure plays a critical role in determining the surface properties of laser-treated magnesium alloys.
The purpose of this paper is to study the solidification microstructures of AZ91D Mg alloy following millisecond- and nanosecond-pulse
Nd:YAG laser irradiation. The solidification microstructural evolution of laser-melt AZ91D Mg alloy was investigated using
X-ray diffractometry, scanning electron microscopy, energy-dispersive X-ray spectrometer and transmission electron microscopy.
Much refined α-Mg phase and β-Mg17Al12 intermetallics were observed in the microstructure after laser surface melting. Periodic and successive structure was observed
in the millisecond irradiated surface and the melt depth was more than 100 μm. The solidification microstructure was mainly
cellular/dendrite structures together with a large number of β-Mg17Al12 nano-particles. Micron holes were found in the nanosecond irradiated surface and the melt depth was shallow at 50 μm. Millisecond-pulse
Nd:YAG laser was found to be more suitable for Mg alloy surface treatment due to sufficient melt depth. 相似文献
10.
L. J. Li K. Yu H. B. Mao Z. Q. Zhu 《Applied Physics A: Materials Science & Processing》2010,99(4):865-869
By using a thermal evaporation and condensation method, Cu-doped SnO2 nanobelts were synthesized on silicon substrate. High-resolution transmission electron microscopy and energy dispersive X-ray
spectroscopy studies of Cu-doped SnO2 nanobelts demonstrate that the nanobelts are single-crystal structures and Cu is homogeneously doped into the SnO2 lattice. X-ray diffraction further confirmed the single-phase nature of these nanobelts. The photoluminescence measurements
of the nanobelts and samples annealed in oxygen were measured from 77 K to 300 K. Field-emission measurements demonstrated
that the Cu-doped nanobelts possessed good performance with a turn-on field of ∼2.9 V/μm and a threshold field of ∼4.8 V/μm. 相似文献
11.
H. Q. Bao X. L. Chen H. Li G. Wang B. Song W. J. Wang 《Applied Physics A: Materials Science & Processing》2009,94(1):173-177
The growth of AlN fibers using sublimation method was investigated in the temperature range from 1600 °C to 2000 °C. Large-scale
AlN fibers are obtained with diameters from 100 nm to 50 μm and lengths up to several millimeters. The fiber morphology and
growth direction are characterized by X-ray diffraction (XRD), field emission scanning electron microscope (SEM), high-resolution
transmission electron microscopy (HRTEM), and Raman scattering. The fibers change from wire-like to prism-like in morphology
and increase in diameter as rising temperatures, accompanying a transformation in axial direction from [10
] to [0001]. The transformation in the growth direction is discussed in terms of AlN structure and supersaturation of AlN
gas species. These results provide useful information for controlling the growth of large-scale AlN fibers. 相似文献
12.
Akhmet A. Galeev V. M. Vinokurov F. A. Mouraviev Yu. N. Osin 《Applied magnetic resonance》2009,35(3):473-479
Lower Permian (280 to 300 Ma) evaporite dolomite rocks from the western part of the East European platform were studied by
optical microscopy, scanning electron microscopy with microprobe analysis, and X-band electron paramagnetic resonance (EPR).
Microscopic studies showed that many dolomite grains consist of an aggregation of submicron dolomite crystals (0.2–2 μm) as
a spheroidal nucleus which is overgrown by a larger dolomite rhombohedron (5–20 μm). The EPR spectrum of a raw rock sample
is mainly determined by thermally unstable radiation centers and Mn2+ ions substituted at Ca and Mg sites in the dolomite crystal structure. The presence of dispersed organic matter at low concentrations
was revealed from the backscattered electron images with a microprobe analysis of carbon-enriched areas on cleaved surfaces
and the registration of the carbon-centered free organic radical signal in EPR spectra of heat-treated samples. A model of
two successive growing stages for dolomite grains is suggested: the dolomite (or dolomite precursor) nucleation and aggregation
in the colloidal stage to form suspended organo-mineral particles before the gravitational settling, and early diagenetic
overgrowth at lower temperature and more stable environment of the marine bottom to form a dolomite rhombohedron. The observation
of both growing stages for dolomite grains indicates that there was no recrystallization in the later stages of the rock history. 相似文献
13.
Susanne Seyffarth Hans-Ulrich Krebs 《Applied Physics A: Materials Science & Processing》2010,99(4):735-740
Triangular and quadratic Cu pyramids were epitaxially grown on Si(111) and Si(100) substrates, respectively, by pulsed laser
deposition at elevated substrate temperatures above 200°C as well as by post-annealing of closed Cu layers prepared at room
temperature. In both cases, three-dimensional pyramids with edge lengths of up to 9 μm were obtained, as observed by scanning
electron microscopy and atomic force microscopy. Although the macroscopic shape is a pyramid, microscopically the islands
consist of columnar grains (with lateral sizes of only about 50 nm at 260°C). The size and shape of the pyramids can be controlled
by the substrate used, the amount of material deposited, and the temperature during deposition or annealing. Additionally,
first hints were found that the pyramids can be aligned by structuring the substrate. The formation of such large pyramids
is explained by a fast diffusion of Cu atoms on Si over distances of some μm and a high jump probability to higher pyramid
layers. 相似文献
14.
Large-scale cadmium sulfide (CdS) nanorods with high quality were successfully synthesized by solvothermal method using ethylenediamine
(en) aqueous as solvent. The as-obtained product was investigated by X-ray diffractometer (XRD), high-resolution transmission
electron microscopy (HRTEM), field emission scanning electron microscopy (FE-SEM), ultraviolet–visible (UV–Vis) spectrum and
photoluminescence (PL) spectrum. The length and width of the CdS nanorods were in the range of 1–2 μm, 30–40 nm, respectively.
XRD analysis revealed that the crystal structure of the product was hexagonal phase. Photoluminescence measurement showed
that the nanobelts have two main emission bands around 470 and 560 nm, which should come from the higher-level transition
and the intrinsic transition, respectively. 相似文献
15.
Liang Xu Shuankui Li Zhiguo Wu Huajun Li De Yan Chunyu Zhang Pengju Zhang Pengxun Yan Xudong Li 《Applied Physics A: Materials Science & Processing》2011,103(1):59-65
Nanotip arrays of amorphous carbon with embedded hexagonal diamond nanoparticles were prepared at room temperature for use
as excellent field emitters by a unique combination of anodic aluminum oxide (AAO) template and filtered cathodic arc plasma
(FCAP) technology. In order to avoid nanopore array formation on the AAO surface, an effective multi-step treatment employing
anodization and pore-widening processes alternately was adopted. The nanotips were about 100 nm in width at the bottom and
150 nm in height with density up to 1010 cm−2. Transmission electron microscopy investigation indicates that many nanoparticles with diameters of about 10 nm were embedded
in the amorphous carbon matrix, which was proved to be hexagonal diamond phase by Raman spectrum and selected-area electron
diffraction. There is no previous literature report on the field emission properties of hexagonal diamond and its preparation
at room temperature under high-vacuum condition. The nanotip arrays with hexagonal diamond phase exhibit a low turn-on field
of 0.5 V/μm and a threshold field of 3.5 V/μm at 10 mA/cm2. It is believed that the existence of hexagonal diamond phase has improved the field emission properties. 相似文献
16.
17.
M. K. Fung Y. C. Sun A. M. C. Ng X. Y. Chen K. K. Wong A. B. Djurišić W. K. Chan 《Applied Physics A: Materials Science & Processing》2011,104(4):1075-1080
Indium tin oxide nanowires have been grown by dc sputtering on different substrates without the use of catalysts or oblique
deposition. The nanowire length was of the order of several μm, while their diameter was ∼50–100 nm. Small side branches on
the nanowires were frequently observed. The nanowires were characterized by scanning electron microscopy, transmission electron
microscopy, and X-ray diffraction. The growth mechanism of the nanowires is discussed. 相似文献
18.
A. Sennuga J. van Marwijk A. Boshoff C. G. Whiteley 《Journal of nanoparticle research》2012,14(5):824
The chaperonin protein GroEL was mixed with varying concentrations of K2PtCl4 followed by a 20-fold concentration of sodium borohydride to afford GroEL–platinum nanoparticle complexes in a ratio of between
1:25 and 1:2,000. Typical colour change, from colourless or pale yellow to brown, occurred that was dependent on the amount
of platinum present. These complexes were characterised by UV/Vis, inductively coupled plasma optical emission spectroscopy,
Fourier transform infra red, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy. TEM analysis
revealed that the size of nanoparticles increased as the molar ratio of platinum to GroEL increased with an average size diameter
of 1.72–3.5 nm generated with GroEL–platinum molar ratios of 1:125–1:2,000. Fourier-transform infrared spectroscopy (FTIR)
spectra showed no distinct changes in the structure of GroEL but confirmed that the nanoparticles were attached to the protein.
The effect of platinum nanoparticles on the ATPase activity of GroEL showed an activity of 5.60 μmol min−1 ml−1 (87 % increase over a control) at the molar ratio of GroEL–platinum nanoparticles of 1:25. 相似文献
19.
Mohammod Aminuzzaman Akira Watanabe Tokuji Miyashita 《Journal of nanoparticle research》2010,12(3):931-938
This article describes fabrication of Ag micropatterns on a flexible polyimide (PI) film by laser direct writing using an
Ag nanoparticle-dispersed film as a precursor. Ag micropatterns are characterized by optical microscopy, atomic force microscopy
(AFM), field emission scanning electron microscopy (FE-SEM), surface profilometry, and resistivity measurements. The line
width of Ag micropatterns can be effectively controlled by altering the experimental parameters of laser direct writing especially
laser intensity, objective lens, and laser beam scanning speed etc. Using an objective lens of 100× and laser intensity of
170.50 kW/cm2, Ag micropatterns with a line width of about 6 μm have been achieved. The Ag micropatterns show strong adhesion to polyimide
surface as evaluated by Scotch-tape test. The resistivity of the Ag micropatterns is determined to be 4.1 × 10−6 Ω cm using two-point probe method. This value is comparable with the resistivity of bulk Ag (1.6 × 10−6 Ω cm). 相似文献
20.
?. Tüzün A. Slaoui C. Maurice S. Vallon 《Applied Physics A: Materials Science & Processing》2010,99(1):53-61
In this work, we present extended structural properties of poly-Si thin films fabricated by aluminium-induced crystallization
(AIC) of amorphous silicon (a-Si) on high-temperature glass-ceramic substrates. The silicon nucleation kinetics on glass-ceramic
substrates was investigated by optical microscopy. The crystalline quality of the films was studied by micro-Raman spectroscopy
as a function of exchange annealing conditions. By means of electron backscattering diffraction (EBSD), we have analyzed the
effect of thermal annealing on silicon grain size and its distribution, intra- and inter-grains defects, and on the grains
preferential crystallographic orientation. The optimal thermal annealing condition, allowing 100% crystallized polysilicon
large grains with an average grain size of 26 μm and 〈100〉 oriented, acquired a thermal budget of 475°C and 8 h. 相似文献