共查询到20条相似文献,搜索用时 624 毫秒
1.
M. Dubiel S. Brunsch W. Seifert H. Hofmeister G.L. Tan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):229-232
Ag particles of 3.9 and 5.1 nm mean size in silicate glasses were produced by ion exchange and subsequent annealing at 480
and 600 °C. These thermal treatments may induce stresses in matrix and particles in addition to the well known effect of surface atoms
because of the thermal expansion mismatch of both materials. Structural characterisation of the particles by high-resolution
electron microscopy revealed a size-dependent lattice dilatation quite opposite to the so far observed lattice contraction
of similar metal/glass composites. This result, confirmed by X-ray absorption spectroscopy at the Ag K-edge, is discussed
in terms of an Ag-Ag bond length increase near the particle surface. The temperature-dependent EXAFS spectra (10-300 K) indicate
an increased thermal expansion coefficient of the particles with an increased mean particle size calculated on the basis of
an anharmonic Einstein model. With that the bond length increase can be explained. The results can be interpreted by a combination
of both the particle size effects and the influence of the surrounding matrix.
Received 30 November 2000 相似文献
2.
A. Mougin C. Dufour N. Maloufi K. Dumesnil Ph. Mangin 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):289-296
Single crystal RFe2(110) films were grown by molecular beam epitaxy to a total thickness of 1000 ? at different substrate temperatures ranging
from 450
°
C to 660
°
C. The first stages of growth and the surface morphology of the deposited layers have been studied using Reflection High Energy
Electron Diffraction (RHEED) and Atomic Force Microscopy (AFM). The growth is first strained but further deposit induces the
formation of three-dimensional fully relaxed islands. Subsequently, the morphology of the RFe2(110) nanosystems evolves from anisotropic dots to a smooth surface, as a function of the preparation parameters, i.e. nominal thickness and substrate temperature. It also depends on the rare earth involved in the compound.
Received 29 June 2000 相似文献
3.
D.L. Peng T.J. Konno K. Wakoh T. Hihara K. Sumiyama 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):329-332
Cluster-cluster coalescence process of monodispersed Co clusters with mean diameter d = 8.5 and 13 nm deposited a plasma-gas-condensation-type cluster beam deposition system was investigated by in situ electrical conductivity measurements and ex situ scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and analyzed by percolation concept. The electrical
conductivity measurement and TEM observation indicated that, below temperature T≈ 100°C, the Co clusters in the assemblies maintain their original structure as deposited at room temperature, while that the inter-cluster
coalescence takes place at T > 100°C, although the size distribution and the interface morphology of the clusters showed no marked change at substrate temperatures
T
s≤200°C.
Received 29 November 2000 相似文献
4.
The unique Bi2Te3 tubes were obtained via a simple solvothermal reaction in the presence of ethylenediaminetetraacetic acid disodium salt. The product was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Bi2Te3 nanosheets are vertically grown off the tube wall to form Bi2Te3 tubes. A possible formation mechanism is proposed. 相似文献
5.
C. Herwig J.A. Becker 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):51-54
The growth of small tellurium clusters in helium and the influence of a metal impurity (dysprosium atoms) on the cluster size
distribution are investigated in a double laser vaporization source. A model describing the role of the carrier gas as collision
partner is presented, emphasizing the crucial influence of the gas pressure on cluster formation. Changes in cluster reactivity
due to dysprosium addition are discussed in terms of ionic structures Dy
3 +(Te
N)3 - containing a radical electron.
Received 28 November 2000 相似文献
6.
Dillip K. Pradhan R. N. P. Choudhary B. K. Samantaray Awalendra K. Thakur R. S. Katiyar 《Ionics》2009,15(3):345-352
Polymer–clay nanocomposites consisting of polymer (polyethylene oxide) and NaI as salt with different concentration of organically
modified Na+-montmorillonite (DMMT) have been fabricated and characterized. X-ray diffraction analysis shows that the polymer–salt complexes
have been intercalated into the nanometric silicate layers of DMMT. Fourier transform infrared analysis shows that the polymer
structure in the clay interlayer is similar to that of the polymer–salt complexes, and there is a strong interaction between
the polymer–salt complexes and clay layers. A study of surface morphology using scanning electron microscopy reveals that
microstructure of composites is affected by clay addition. Complex impedance analysis was used to calculate the bulk resistance
of the composites. An enhancement in the conductivity of about one order of magnitude has been observed on 5% clay addition
compared to that of the polymer–salt complexes, and it decreases monotonically for higher clay concentration. The effect of
clay concentration on the structural and physical properties of polymer nanocomposites is well correlated. 相似文献
7.
V. Dureuil C. Ricolleau M. Gandais C. Grigis 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(1):83-88
The crystalline structure of Co clusters embedded in an amorphous Al2O3 matrix was studied by transmission electron microscopy (TEM) and electron diffraction (TED). In the first stage of the growth
a metastable structure (body-centred-cubic) is observed. A face-centred-cubic phase (fcc) is found when the size of the clusters
increases ( diameter > 4 nm). The hexagonal-close-packed phase arises in the fcc phase by a succession of stacking faults at the largest sizes.
The mechanisms of phase transformation have been determined by using high resolution electron microscopy (HREM). The chemical
nature of the clusters, in particular the existence of Co-O bonds, was investigated by using electron energy loss spectroscopy
(EELS).
Received 03 July 2000 and Received in final form 22 December 2000 相似文献
8.
The effect of oxidation on the structure of nickel nanoparticles 总被引:1,自引:0,他引:1
B. Rellinghaus S. Stappert E.F. Wassermann H. Sauer B. Spliethoff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):249-252
The structural properties of nickel nanoparticles which are prepared by means of DC sputtering in argon and subsequently oxidized
in ambient air are reported. Ex situ structural and chemical investigations utilizing (high resolution) transmission electron microscopy and electron energy loss
spectroscopy reveal that the particles consist of a metallic core surrounded by an oxide shell. The lattice constant of the
nickel core is found to increase significantly with decreasing particle size. This widening of the nickel lattice is attributed
to an interfacial stress that originates from the lattice mismatch between nickel and nickel oxide.
Received 21 December 2000 相似文献
9.
The branched crystal morphology of linear polyethylene formed at various temperatures from thin films has been studied by
atomic-force microscopy (AFM), transmission electron microscopy (TEM), electron diffraction (ED) pattern and polymer decoration
technique. Two types of branched patterns, i.e. dendrite and seaweed patterns, have been visualized. The fractal dimension d
f = 1.65 of both dendrite and some of seaweed patterns was obtained by using the box-counting method, although most of the
seaweed patterns are compact. Selected-area ED patterns indicate that the fold stems tilt about 34.5° around the b-axis and polymer decoration patterns show that the chain folding direction and regularity in two (200) regions are quite
different from each other. Because of chain tilting, branched crystals show three striking features: 1) the lamella-like branches
show two (200) regions with different thickness; 2) the crystals usually bend towards the thin region; 3) the thick region
grows faster by developing branches, thus branches usually occur outside the thick region. The branched patterns show a characteristic
width w, which gives a linear relationship with the crystallization temperature on a semilogarithmic plot.
Received 15 March 2002 and Received in final form 29 April 2002 相似文献
10.
Nanoparticles superficial density of charge in electric double-layered magnetic fluid: A conductimetric and potentiometric approach 总被引:2,自引:0,他引:2
A.F.C. Campos F.A. Tourinho G.J. da Silva M.C.F.L. Lara J. Depeyrot 《The European physical journal. E, Soft matter》2001,6(1):29-35
We analyze potentiometric and conductimetric measurements simultaneously performed on Electric Double-Layer Magnetic Fluid
based on cobalt ferrite nanoparticles, in order to obtain the pH-dependence of the particle surface charge density. We propose a mechanism for the charging of the particle surface. This
model considers the ferrofluid solution as a mixture of strong and weak diprotic acids. We show how an exact analytical treatment
involving proton transfer between the particle surface and the bulk solution allows the construction of a speciation diagram
of the charged superficial sites. The saturation value of the superficial density of charge is found to be equal to 0.326
± 0.065 C m-2.
Received 9 May 2001 and Received in final form 17 July 2001 相似文献
11.
L. Raymond J.-M. Laugier S. Schäfer G. Albinet 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(3):355-364
Binary disordered systems are usually obtained by mixing two ingredients in variable proportions: conductor and insulator,
or conductor and super-conductor. They present very specific properties, in particular the second-order percolation phase
transition, with its fractal geometry and the multi-fractal properties of the current moments. These systems are naturally
modeled by regular bi-dimensional or tri-dimensional lattices, on which sites or bonds are chosen randomly with given probabilities.
The two significant parameters are the ratio h = σ
1/σ of the complex conductances, σ and σ
1, of the two components, and their relative abundances p (or, respectively, 1 - p). In this article, we calculate the impedance of the composite by two independent methods: the so-called spectral method,
which diagonalises Kirchhoff's Laws via a Green function formalism, and the Exact Numerical Renormalization method (ENR). These methods are applied to mixtures of
resistors and capacitors (R-C systems), simulating e.g. ionic conductor-insulator systems, and to composites constituted of resistive inductances and capacitors (LR-C systems),
representing metal inclusions in a dielectric bulk. The frequency dependent impedances of the latter composites present very
intricate structures in the vicinity of the percolation threshold. In this paper, we analyse the LR-C behavior of compounds
formed by the inclusion of small conducting clusters (“n-legged animals”) in a dielectric medium. We investigate in particular their absorption spectra who present a pattern of sharp
lines at very specific frequencies of the incident electromagnetic field, the goal being to identify the signature of each
animal. This enables us to make suggestions of how to build compounds with specific absorption or transmission properties
in a given frequency domain.
Received 16 August 2002 Published online 14 February 2003
RID="a"
ID="a"e-mail: laurent.raymond@l2mp.fr
RID="b"
ID="b"e-mail: steffen.schaefer@l2mp.fr
RID="c"
ID="c"UMR CNRS 6137 相似文献
12.
L. Yang J. Chen H. Yang J. Dong 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(2):215-219
We have constructed four types single-wall carbon nanotube intramolecular junctions (IMJs) of (5,5)/(8,0), (5,5)/(10,0), (5,5)/(9,0)A, and (5,5)/(9,0)B along a common axis, and calculated their electronic and transport properties using a tight binding-based Green's function
approach that is particular suitable for realistic calculation of electronic transport property in extended system. Our results
show that quasi-localized states can appear in the metal/semiconductor heterojunctions ((5,5)/(8,0) and (5,5)/(10,0)junctions),
which is desirable for the design of a quantum device; and the conductance of M-M IMJs is very sensitive to the connectivity
of the matching tubes, certain configurations of connection completely stop the flow of electron, while others permit the
transmission of the current through the interface. These results may have implications for the device assembly and manipulation
process of all carbon nanotubes-based microelectronic elements.
Received 14 January 2003 / Received in final form 25 February 2003 Published online 4 June 2003
RID="a"
ID="a"e-mail: lfyzz@yahoo.com.cn 相似文献
13.
A. Saffarzadeh 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(2):149-153
Spin-polarized tunneling in FMS/M/FMS double tunnel junctions where FMSs are ferromagnetic semiconductor layers and M is a
metal spacer is studied theoretically within the single-site coherent potential approximation (CPA). The exchange interaction
between a conduction electron and localized moment of the magnetic ion is treated in the framework of the s-f model. The spin polarization in the FMS layers is observed to oscillates as a function of the number of atomic planes in
the spacer layer. Amplitude of these oscillations decreases with increasing the exchange interaction in FMS layers.
Received 9 June 2001 and Received in final form 20 August 2001 相似文献
14.
V.S. Shelkovsky S.G. Stepanian I.K. Galetich M.V. Kosevich L. Adamowicz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):421-430
A combined experimental-theoretical approach to modeling of building blocks of recognition complexes formed by nucleic acid
bases and the amino-acids side-chain amino group is reviewed. The approach includes the temperature dependent field-ionization
mass spectrometry and ab initio quantum chemical calculations. The mass spectrometric technique allows determination of interaction enthalpies of biomolecules
in the gas phase, and the results it produces are directly comparable to the results obtained through theoretical modeling.
In our works we have analyzed both thermodynamic and structural aspects of the recognition complexes of four canonical nucleic
acid bases and acrylamide, which models the side chain of asparagine and glutamine. It has been shown that all bases can interact
with amide group of the amino acids via their Watson-Crick sites when being incorporated into a single strand DNA or RNA. Stability of the complexes studied, expressed
as - ΔH (kJ mole-1) decreases as: m9Gua (- 59.5) > m
1Cyt (- 57.0) > m
9Ade (- 52.0) ≫m
1Ura (- 40.6). We have determined that in the double stranded DNA only purine bases can be recognized.
Received 5 February 2002 and Received in final form 14 March 2002 Published online 13 September 2002 相似文献
15.
M. Hiane J. Ebothé 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(4):485-495
We show that the electrodeposition of Ni-Zn alloys at the lowest growth velocities, v < 0.5μm/s, exclusively proceeds from an abnormal co-deposition phenomenon. The growth process in this v region greatly depends on the initial [Co2+] concentration of the film deposition bath. A theoretical approach of this process including the role of the saturation surface
roughness of the alloy, , leads to an estimation of the transport properties of the ad-atoms involved during the deposit formation. Their surface
diffusion coefficient varying between 1.76×10-10 and 2.40×10-8 cm-2/s exhibits a minimal value, D
s = 2.10×10-10 cm-2/s located between v = 0.17 and 0.35μm/s. The spatial scaling analysis of the local roughness, σ, examined according to the power-law σ≈L
α reveals that the resulting roughness exponents concurs with the Kardar-Parisi-Zhang dynamics including the restricted surface
diffusion. Two main v regions leads to different fractal textural features of the alloy film surface. Below 0.10 μm/s, the roughness exponent obtained
is α≈ 0.6, depicting a limited ad-atom mobility. Over v = 0.30μm/s, this exponent stabilises at α≈ 0.82, indicating an increase of the surface diffusion.
Received 16 August 2000 and Received in final form 20 June 2001 相似文献
16.
A. Michel V. Pierron-Bohnes J.P. Jay P. Panissod S. Lefebvre M. Bessière H.E. Fischer G. Van Tendeloo 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):225-239
Epitaxial Co/Mn multilayers (0.75 to 6 nm Co, 0.4 nm Mn layer thickness) have been grown on mica substrates covered by a (0002)
Ru buffer layer. The structural properties of these layers have been studied using X-ray diffraction, nuclear magnetic resonance
(NMR), and high resolution transmission electron microscopy (HRTEM). The Co layers, grown as face centred cubic (fcc), were
found to be stabilised by the very thin Mn layers. Data obtained using X-ray diffraction and NMR were analysed and found to
be in good agreement, while Monte-Carlo simulations were used to interpret the data and calculate the expected diffracted
intensity and NMR spectra. The HRTEM data show that the Mn layers give rise to a large strain contrast extending, in the growth
direction, over a distance which exceeds the thickness of the Mn layers. The superlattices could be described as having an
fcc structure containing randomly located stacking faults with varying densities. The results verify the presence of a dominant,
almost perfect phase of fcc stacking, and of a faulted hcp phase, while the number of defects increases with the Co layer
thickness.
Received 27 October 1999 and Received in final form 29 May 2000 相似文献
17.
W.L. Zhou E.E. Carpenter J. Lin A. Kumbhar J. Sims C.J. O'Connor 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):289-292
Pure metal iron nanoparticles are unstable in the air. By a coating iron on nanoparticle surface with a stable noble metal,
these air-stable nanoparticles are protected from the oxidation and retain most of the favorable magnetic properties, which
possess the potential application in high density memory device by forming self-assembling nanoarrays. Gold-coated iron core-shell
structure nanoparticles (Fe/Au) synthesized using reverse micelles were characterized by transmission electron microscopy
(TEM). The average nanoparticle size of the core-shell structure is about 8 nm, with about 6 nm diameter core and 1∼2 nm shell.
Since the gold shell is not epitaxial growth related to the iron core, the morié pattern can be seen from the overlapping
of iron core and gold shell. However, the gold shell lattice can be seen by changing the defocus of TEM. An energy dispersive
X-ray spectrum (EDS) also shows the nanoparticles are air-stable. The magnetic measurement of the nanoparticles also proved
successful synthesis of gold coated iron core-shell structure. The nanoparticles were then assembled under 0.5 T magnetic
field and formed parallel nanobands with about 10 μm long. Assembling two dimensional ordered nanoarrays are still under going.
Received 29 November 2000 相似文献
18.
M. Gutowski I. Dabkowska J. Rak S. Xu J.M. Nilles D. Radisic K.H. Bowen Jr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):431-439
The photoelectron spectra (PES) of anions of uracil-glycine and uracil-phenylalanine complexes reveal broad features with
maxima at 1.8 and 2.0 eV. The results of ab initio density functional B3LYP and second order M?ller-Plesset theory calculations indicate that the excess electron occupies a
π* orbital localized on uracil. The excess electron attachment to the complex can induce a barrier-free proton transfer (BFPT)
from the carboxylic group of glycine to the O8 atom of uracil. As a result, the four most stable structures of the anion of
uracil-glycine complex can be characterized as the neutral radical of hydrogenated uracil solvated by the anion of deprotonated
glycine. The similarity between the PES spectra for the uracil complexes with glycine and phenylalanine suggests that the
BFPT is also operative in the case of the latter anionic species. The BFPT to the O8 atom of uracil may be related to the
damage of nucleic acid bases by low energy electrons because the O8 atom is involved in a hydrogen bond with adenine in the
standard Watson-Crick pairing scheme.
Received 6 April 2002 Published online 13 September 2002 相似文献
19.
A. Pelc W. Sailer P. Scheier N.J. Mason T.D. Märk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):441-444
Using a high resolution electron energy monochromator low energy electron attachment to formic acid is studied for the first
time by means of mass spectrometric detection of the product anions. The largest dissociative electron attachment (DA) cross-section
produces HCOO
-+H with weaker channels for OH- and O- becoming apparent at higher incident energies.
Received 23 January 2002 and Received in final form 9 February 2002 Published online 13 September 2002 相似文献
20.
Aqueous solutions of a well-defined poly(N-isopropylacrylamide-co-sodium 2-acrylamido-methylpropanesulfonate) (NIPAM/NaAMPS in a 95/5 molar ratio) have been investigated by means of small-angle
neutron scattering (SANS) and rheological experiments as a function of temperature ( 25°
C
T
60°
C) and polymer concentration ( 0.5wt%
C
12wt%). The solutions remain optically transparent and isotropic over the whole temperature range, in contrast with the homopolyNIPAM
which precipitates above its lower critical solution temperature (LCST = 32°
C). Upon addition of salt, the systems undergo a micro-macrophase separation. At temperatures above 45°
C, the SANS spectra exhibit a sharp peak at a scattering wave vector, q
max, which increases slightly with temperature. At high temperature ( T∼ 60°
C), the scattered intensity follows a power law I(q) ∼q
-4 in the asymptotic regime, characteristic of two-density media with sharp interfaces, and q
max is found to vary with polymer concentration as q
max∼C
0.22. Estimates of the typical sizes give values between 40 ? and 200 ?. These results provide a strong evidence of a thermally
induced microphase separation, which is corroborated by the very sharp increases of the viscosity (over 2 decades) and of
the stress relaxation time of the solutions, occurring in the temperature range where the scattering peak is observed. The
results are discussed and compared with the theoretical models proposed for weakly charged polyelectrolytes in a poor solvent.
Received 1 October 2001 相似文献