共查询到20条相似文献,搜索用时 15 毫秒
1.
Atomistic calculations of the elastic constants for a bulk nanostructured material that consists of a layered structure where alternating layers meet along high angle grain boundaries and where atoms interact via a Lennard-Jones potential are presented. The calculations of the elastic constants were performed in the frame of homogeneous deformations for a wide range of layer widths ranging from 2.24 up to 74.62 nm. The results showed that the relaxation of the atomic structure affects the elastic constants for the cases where more than 5% of atoms are located in the GB region. Also it was found that the way that external stresses are applied on the system affects the values of the obtained elastic properties, with the elastic constants related to the characteristic directions of the grain boundary being the most affected ones. The findings of this work are of interest for the fabrication methods of nanostructured materials, the measurement methods of their elastic properties as well as multiscale modeling schemes of nanostructured materials. 相似文献
2.
Based on the thermodynamic and thermophysical properties of bulk materials, Gibbs free energy for nanostructured materials is obtained and used to study the size-dependent melting point depression phenomenon. The effects of volume change due to fusion, the thermal expansion and the temperature dependency of surface free energy of bulk materials on the melting point depression are investigated. Conversely, the solid surface free energy of bulk materials is also researched by means of the size-dependent melting temperature of nanostructured materials. 相似文献
3.
Synthesis and photophysical properties of polyamides containing in-chain porphyrin and [60]fullerene
Haiying Zhao Chen Chen Yizhou Zhu Mingzhu Shi Jianyu Zheng 《Journal of nanoparticle research》2012,14(3):765
Conjugated polyamides containing porphyrin and [60]fullerene (C60) in the main chain were prepared by a direct polycondensation of the 3′H,3″H-dicyclopropa[1, 9:16, 17] [5, 6]fullerene-C60-I
h
-3′,3″-dicarboxylic acid and 5,15-bis(4-aminophenyl)-10,20-bis(3,5-dialkoxyphenyl)porphyrin in the presence of triphenyl phosphite
and pyridine. Gel permeation chromatography (GPC) analysis of the polyamides showed the weight-average molecular weight was
about 23,626–23,736, and the temperature at 5% weight loss determined by thermogravimetric analysis (TGA) was above 216 °C.
The transmission electron microscopy (TEM) images displayed the regular one-dimensional linear arrays of the polyamides with
lengths exceeded 200 nm. The photoinduced electron transfer from porphyrin to C60 in the polyamides was observed in nanosecond laser-flash photolysis experiments at ambient temperature, which produced a
charge-separated state (porphyrin radical cation–C60 radical anion pair) with a lifetime as long as 40 μs. The calculated ratio of k
CS/k
CR was found to be 2.1 × 104. They could have potential applications for photoelectronic devices, organic solar cells and so on. 相似文献
4.
Nanostructured polymer materials with interesting morphological variation, which include three dimensionally interconnected uniform nanoporous network arrays (volume- and surface-templated ordered arrays) and hollow core spheres were synthesized by inducing different polymerization process of phenol and formaldehyde as a precursor over silica templates (ordered silica colloidal crystals or individual silica particles). The pore sizes of the resulting nanostructured polymer materials can be easily controlled by monitoring the sizes of silica spheres, while their morphologies were modulated by controlling the initiation sites of the acid-catalyzed condensation reaction of the same polymer precursor and by modifying silica templates. 相似文献
5.
Wei Li Ping LiuFengcang Ma Xinkuan LiuYonghua Rong 《Physica B: Condensed Matter》2011,406(13):2540-2542
In order to explain the experimental facts that start temperatures of reverse martensite transformation (As) for nanostructured Fe-Ni and Co are lower than those for their coarse-grained counterparts, a thermodynamic model was established in this paper. The thermodynamic analysis shows that the decrease of As for nanostructured Fe-Ni and Co can be attributed to the difference of surface free energy for martensite and austenite. The correlation between the decrease of As and start temperature of martensitic transformation (Ms) in nanostructured material is further proposed. 相似文献
6.
Marcelo Hawrylak Herbst Gilson Herbert Magalhães Dias 《Journal of Physics and Chemistry of Solids》2003,64(12):2423-2428
Evidence of chemical reactivity of solid platinum-fullerene [PtnC60] compounds towards carbon monoxide is presented. The interaction was systematically studied by means of infrared spectroscopy, X-ray powder diffraction and thermogravimetric analysis. The interaction of carbon monoxide, even under low pressure, is confirmed by the appearance of infrared absorption bands in the CO stretching region at 2064, 2014 and 1991 cm−1 for the carbonylation products. The exceptions were those products with low Pt:C60 ratios, which also displayed bands at 1870 and 1830 cm−1. The data suggest that the CO coordination depends on the specific morphology of the solids, the original Pt:C60 ratio, and the carbon monoxide nominal pressure. Therefore, these results indicate the formation of [(CO)xPt]m species supported in a fullerene matrix mixed with [Ptn−mC60] compounds. As there is a competition between carbon monoxide and fullerene molecules for the electronic density at the platinum centers, the nature of the CO interaction with [PtnC60] was found to be destructive, leading to the displacement of the latter. Nevertheless, the platinum-carbonyl species formed presents relatively high stability, as shown by desorption tests. 相似文献
7.
A water-soluble fullerene [C60] is prepared with fullerene [C60] and a mixture of strong inorganic acids at the ratio (v/v) of 3:1 under ultrasonic condition at 25-43 degrees C. The MALDI-TOF MS and 13C-NMR spectra confirmed that the product of a water-soluble fullerene compound was C60. 相似文献
8.
Y. Gao Q. Chang W. Jiao H. Ye Y. Li Y. Wang Y. Song D. Zhu 《Applied physics. B, Lasers and optics》2007,88(1):89-92
The optical limiting performance of lead nanowires in chloroform, ethanol and dimethylformamide was measured with 532-nm,
8-ns-duration laser pulses. Experiments showed that the optical limiting is strong and solvent dependent. The origins and
the solvent effect of the optical limiting were analyzed. It is proposed that the absorption-induced scattering is the main
role responsible for the optical limiting behavior and the solvent effect.
PACS 42.65.An; 42.65.Hw; 42.65.Jx 相似文献
9.
L. Zoppi L. Colombo D. Donadio 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):335-340
Hydrogen incorporation in nanostructured carbon films grown by supersonic cluster beam deposition has been theoretically investigated
by classical molecular dynamics. Simulations are shown to enlight the role of the local nanostructure on the formation of
hydrogen-related complexes in different carbon environments.
Received 23 January 2002 Published online 6 June 2002 相似文献
10.
G. Carotenuto L. Pasquini E. Milella M. Pentimalli R. Lamanna L. Nicolais 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(4):545-551
Nano-sized cobalt clusters passivated by alkane-thiol molecules were obtained by the action of concentrated thiol solutions
on micrometric cobalt particles. Thiol molecules caused an erosive process on the metal grains with the consequent formation
of nano-sized metal debris and cobalt thiolate as by-product. The final material microstructure was composed by cobalt clusters
embedded into a continuum cobalt thiolate matrix. Depending on the thiol molecule length, the material texture ranged from
rubbery to waxy. These new types of nanocomposite materials were found to be crystalline, thermally stable up to ca. 300 °C, intensely red colored, and high hydrophobic. In addition, they generated polymeric structures when dissolved in non-polar
solvents.
Received 27 September 2002 Published online 6 March 2003
RID="a"
ID="a"e-mail: giancaro@unina.it 相似文献
11.
Shamil K. Latypov Sergey V. Kharlamov Anton A. Muravev Alsu A. Balandina Svetlana E. Solovieva Igor S. Antipin Alexander I. Konovalov 《Journal of Physical Organic Chemistry》2013,26(5):407-414
According to the quantum chemical calculations and Dynamic NMR experiments in the distally disubstituted classical and thiacalix[4]arenes (CCA and TCA) in addition to the C2v symmetrical pinched cone (PC) conformation, the distorted cone (DC) form with an approximate Cs overall symmetry (with two OH groups bonded to one oxygen atom) also corresponds to the energy minimum. Moreover, in DC form, two different mutual orientations of O–R groups at a lower rim lead to two stable conformations: the first ‐ with both these groups directed outward, the second ‐ with both these groups pointing toward the same direction. In CCA, the PC is essentially favoured over the DC, while in TCA, energies of these forms are similar or the latter may be even preferable. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
12.
13.
The reactions of fullerene[C60] with 2′-azidoethyl 2,3,4,6-tetra-O-acetyl-α-d-mannopyranoside (2a) and 2′-azidoethyl 2,3,4,6-tetra-O-acetyl-β-d-galactopyranoside (2b) under ultrasonic irradiation cause the cycloaddition of 2′-azidoethyl glycosides to fullerene[C60] and lead to d-glycosyl fullerene[C60] derivatives 3a and 3b, respectively. The glycosyl fullerene[C60] derivatives were characterized by 1H and 13C NMR, UV–vis, FAB-MS, FT-IR spectra and were a 1:1 glycoside fullerene [C60]-adduct. 相似文献
14.
L. M. Ramaniah M. Boero 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):369-374
We report the first-principles Car-Parrinello molecular dynamics study of the behaviour of a single transition metal Ta atom
on fullerene C60, at different temperatures, and for both neutral and charged clusters. We seek to characterise the
motion of the lone Ta metal atom on the C60 surface, contrasting its behaviour both with that of three Ta atoms, as well as with a single alkali metal atom on the cage
surface.
Our earlier simulations on C60Ta3 had revealed that the Ta atoms on the surface of
the fullerene are affected by a rather high mobility, and that the motion of these atoms is highly correlated due to Ta-atom-Ta-atom
attraction. Earlier, experimental studies of a single metal atom (K, Rb) on the surface of a C60 molecule had led to the
inference that at room temperature the metal atom skates freely over the surface, the first direct evidence for which was presented by us in earlier first principles molecular dynamical simulations. 相似文献
15.
R. F.M. Lobo N. T. Silva B. M.N. Vicente I. M.V. Gouveia F. M.V. Berardo J. H.F. Ribeiro 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):35-45
The crossed molecular beam technique is used for producing C60- species through potassium-buckyball collision processes, and studying the collision dynamics in an energy ranging from 10 eV
up to 500 eV. At low collision energies only the negative parent ion is formed. As long as the collision energy is increased
the fragmentation pattern of the fullerene negative ion could be identified and relative total cross-sections could be measured.
Surprisingly, some satellite contributions have been observed in the band structure of C60- parent ion time-of-flight spectrum, which points to the existence of distinct conformational C60- isomers, which are likely to be formed during the collision, favoured by the strong polarization of the C60- in the presence of the K+ projectile ion. Such presumed detection of different spheroidal metastable C60- conformers was made possible due to an electric effect operating at the nanoscale. 相似文献
16.
Dmitri V. Konarev Dmitri V. Lopatin Alexey V. Umrikhin Gunzi Saito Alexey L. Litvinov 《Journal of Physics and Chemistry of Solids》2005,66(5):711-715
A new molecular complex of C60 with tetrabenzo(1,2-bis[4H-thiopyran-4-ylidene]ethene), Bz4BTPE C60 (1) has been obtained. The complex has a layered structure in which closely packed hexagonal layers of C60 alternate with the layers composed of Bz4BTPE molecules. The complex has a neutral ground state according to UV-vis-NIR spectrum. It has been found that single crystals of 1 show low ‘dark’ conductivity of σ∼10−10 (Ω cm)−1. A 102 increase in photocurrent has been observed upon illuminating the crystal with white light. Photoconductivity of 1 is sensitive to magnetic field with B0<1 T and increases up to 5% in magnetic field. The photoconductivity spectra of the complex indicate that free charge carriers are generated in the UV-visible range mainly by the Bz4BTPE excitation (the peaks at 622, 562, 472 and 348 nm) with a possible contribution of charge transfer excitations between neighboring C60 molecules (the peak at 472 nm). 相似文献
17.
S. W. Tang L. L. Sun J. D. Feng H. Sun R. S. Wang Y. F. Chang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,53(2):197-204
A systematic investigation of D3 C32 fullerene and its derivatives C32Xn (X = H and Cl) has been performed using B3LYP/6-31G(d) method based on the density functional theory. The geometry structures,
reaction energies, relative stabilities, and electronic properties have been studied. By investigating the possible C32Xn (X = H and Cl) molecules, C32H2 and C32Cl2 behave more thermodynamically accessible with respect to other derivatives. The frontier molecular orbitals and electronic
density of states calculations of C32X2 system indicate that H and Cl passivation have less contribution to the electronic structures, but significantly improve
the stability of D3 C32 fullerene. Finally, the 13C NMR chemical shifts of C32H2 and C32Cl2 have been simulated to provide helpful information for further experiment identification. 相似文献
18.
19.
S. Duffe T. Irawan M. Bieletzki T. Richter B. Sieben C. Yin B. von Issendorff M. Moseler H. Hövel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(3):401-408
The low energy deposition of silver cluster cations with
561 (±5) atoms on a cold fullerene covered gold surface has
been studied both by scanning tunneling microscopy and molecular
dynamics simulation. The special properties of the
C60/Au(111) surface result in a noticeable fixation of the
clusters without a significant change of the cluster shape. Upon
heating to room temperature we observe a flattening or shrinking
of the cluster samples due to thermal activation. Similar changes were observed also for mass selected Ag clusters with other
sizes. For comparison
we also studied Ag islands of similar size, grown by low
temperature deposition of Ag atoms and subsequent annealing. A
completely different behavior is observed with much broader size
distributions and a qualitatively different response to
annealing. 相似文献
20.
The reaction of C70 by ultrasonication with various oxidants such as 3-chloroperoxy benzoic acid (Fluka 99%), 4-methyl morpholine N-oxide (Aldrich 97%), chromium (VI) oxide (Aldrich 99.9%), and oxone® monopersulfate compound, at room temperature causes the oxidation of fullerene [C70(O)n] (n=1–2 or n=1). The FAB-MS, UV–visible, FT-IR spectra, and HPLC analysis confirmed that products of fullerene oxidation are [C70(O)n] (n=1–2 or n=1). 相似文献