共查询到20条相似文献,搜索用时 46 毫秒
1.
采用MEVVA源(metal vapor vacuum arc ion source)引出的强束流脉冲Ag,Cu离子先后注入到SiO2玻璃,x射线光电子能谱仪(XPS)分析显示Ag,Cu大多仍为金属态,有部分氧化态Cu存在.透射电镜观察分析和光学吸收谱都表明在衬底中形成了纳米合金颗粒.结合有效媒质理论,得到模拟的光学吸收谱,与实验结果基本符合,较好地验证了以上结论.样品退火后颗粒发生分解,分解的颗粒在氧化气氛下被氧化,且有部分向样品表面蒸发;在还原气氛下氧化态元素被还原并成核生长.故
关键词:
离子注入
纳米颗粒
退火
光学吸收率 相似文献
2.
S. Padovani F. D'Acapito E. Cattaruzza A. De Lorenzi F. Gonella G. Mattei C. Maurizio P. Mazzoldi M. Montagna S. Ronchin C. Tosello M. Ferrari 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(1):11-17
Composite silica films containing metal nanoclusters were prepared by the rf- sputtering technique, in which SiO2 was co-deposited with gold+copper, gold+silver, or copper+silver. The formation of either pure or alloy clusters was studied
by extended X-ray absorption fine structure spectroscopy and transmission electron microscopy. For all systems, the presence
of alloy aggregates was evidenced. Moreover, small amounts of pure metal aggregates as well as dispersed or oxidized dopants
were observed.
61.46.+w Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals – 61.10.Ht X-ray absorption spectroscopy:
EXAFS, NEXAFS, XANES, etc. – 81.05.Pj Glass-based composites, vitroceramics
Received 29 June 2001 相似文献
3.
Highly stable and spherical silver nanoparticles, stabilized by methoxycarbonyl-terminated hyperbranched poly(amine-ester)
(HPAE-COOCH3), were synthesized in water with reducing AgNO3/HPAE-COOCH3 using two methods, viz. NaBH4 and ultraviolet irradiation. HPAE-COOCH3 was found to play a key role in the formation of nanoparticles. UV–visible absorption, Transmission electron microscopic
(TEM), and Fourier transform infrared spectroscopy (FT-IR) had been used to study the structure and characterization of the
silver nanoparticles. The absorption peaks of the silver nanoparticles appear at ~420 nm in UV–visible absorption spectra;
average particle size reduced by NaBH4 is ~30 nm, which is ~10 and ~15 nm, respectively, when ultraviolet irradiation time is 12 and 24 h. FT-IR spectra confirm
that there is strong interaction between silver nanoparticles and HPAE-COOCH3. And silver nanoparticles/HPAE-COOCH3 aqueous solution can keep stable for more than 3 months. 相似文献
4.
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
5.
Absorption and photoluminescence properties of silver clusters in SiO<Subscript>2</Subscript> matrix
Igor A. Gladskikh Polina V. Gladskikh Tigran A. Vartanyan 《Optical and Quantum Electronics》2017,49(1):41
Absorption and luminescence properties of silver nanoclusters embedded in SiO2 matrixes were studied experimentally. Thin SiO2 films with different amount of silver were produced by co-deposition of Ag and SiO2 onto the silica substrates in vacuum. The thus obtained films possess three peaks in absorption spectra at 297, 329 and 401 nm and two peaks in luminescence spectra at about 500 and 650 nm. We ascribed these spectral features to silver nanoclusters of different sizes that present in the film. Thermal annealing transforms both absorption and emission spectra of the films. Lager clusters that are formed after annealing possess one absorption band at 350–450 nm and one luminescence band at 510 nm. The luminescence was observed only in samples with the silver content of less than 2.2%. Quenching of the luminescence in samples with higher concentration of silver is due to the presence of larger particles with plasmonic properties. 相似文献
6.
V. A. Terekhov S. Yu. Turishchev K. N. Pankov I. E. Zanin E. P. Domashevskaya D. I. Tetelbaum A. N. Mikhailov A. I. Belov D. E. Nikolichev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2011,5(5):958-967
Films obtained using molecular-beam deposition of SiO powder on c-Si (111) substrates for the purpose of SiO2 system formation with silicon nanocrystals were investigated before and after
900–1100°C annealing by photoluminescence, ultrasoft X-ray emission spectroscopy, X-ray photoelectron spectroscopy, X-ray
absorption near-edge structure spectroscopy, and X-ray diffraction. The appearance of (111)-oriented luminescent silicon nanoclusters
in considerable amounts upon annealing at T = 1000–1100°C is established in the investigated films. An anomalous phenomenon of X-ray absorption quantum yield intensity
reversal for the L
2,3 elementary silicon edge is detected. Models for this phenomenon are suggested. 相似文献
7.
采用自悬浮定向流技术制备银团簇纳米颗粒,理论分析了银团簇的成核机理与影响因素,实验研究了制备条件和工艺。结果表明:惰性气体的冷却效率、气体流速和压强、金属熔球的温度和大小是控制颗粒尺寸大小及分布的关键条件,制备粒径小于10 nm的团簇颗粒须采用氦气为载流气体;团簇颗粒流速越大,颗粒粒径越小,尺寸分布越窄,但颗粒生成数量越少。性能表征说明:制备的颗粒呈较规则的球形,为面心立方结构,分散均匀,表面纯净无氧化,粒径分布窄。理论与实验研究了银团簇纳米颗粒的光学吸收谱性质,证明表面等离子共振吸收峰与颗粒的尺寸有很强的相关性,随着颗粒尺寸的减小,由于量子尺寸效应,吸收峰将发生宽化和蓝移。 相似文献
8.
X. C. Jiang S. X. Xiong C. Y. Chen W. M. Chen A. B. Yu 《Journal of nanoparticle research》2011,13(10):5087-5101
This study demonstrates a facile but effective polyol-thermal reaction method for the synthesis of silver nanowires in autoclaves
(160–180 °C). By this approach, the generated silver nanowires show an average diameter of ~40 nm and length up to tens of
micrometers with a high yield and potential for large-scale production. To achieve shape- and size-controlled Ag nanowires,
several experimental parameters were investigated and optimized, including surface controller(s), molar ratio of surfactant(s)
to silver ions, temperature, and concentration of reactants. The structure and composition of silver nanowires were characterized
by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), scanning electron microscopy (SEM), and X-ray diffraction
(XRD) techniques. In particular, the twinned crystal structure observed in both spherical particles and nanowires was analyzed
by HRTEM technique, and the possible formation and growth mechanisms were discussed. The optical property of the as-prepared
product was measured by ultraviolet–visible (UV–vis) spectroscopy. The sensing detection of metal ions (e.g., Hg2+) using the obtained silver nanowires in aqueous media was finally investigated. 相似文献
9.
R. Nirmala Faheem A. Sheikh Muzafar A. Kanjwal John Hwa Lee Soo-Jin Park R. Navamathavan Hak Yong Kim 《Journal of nanoparticle research》2011,13(5):1917-1927
Bovine femur bone hydroxyapatite (HA) containing silver (Ag) nanoparticles was synthesized by thermal decomposition method
and subsequent reduction of silver nitrate with N,N-dimethylformamide (DMF) in the presence of poly(vinylacetate) (PVAc). The structural, morphological, and chemical properties
of the HA–Ag nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission
scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS).
TEM images showed that the Ag nanoparticles with size ranging from 8 to 20 nm and were arranged at the periphery of HA crystals.
Bactericidal activity of HA–Ag with different concentration of Ag nanoparticles immobilized on the surface of HA was investigated
against gram-positive Staphylococcus aureus (S. aureus, non-MRSA), Methicillin resistant S. aureus (MRSA) and gram-negative Escherichia coli (E.
coli) by the disc diffusion susceptibility test. The HA–Ag nanoparticles showed that broad spectrum activity against non-MRSA,
MRSA, and E. coli bacterial strains. 相似文献
10.
In this paper, data concerning the effect of pH on the morphology of Ag–TiO2 nanocomposite during photodeposition of Ag on TiO2 nanoparticles is reported. TiO2 nanoparticles prepared by sol–gel method were coated with Ag by photodeposition from an aqueous solution of AgNO3 at various pH levels ranging from 1 to 10 in a titania sol, under UV light. The as-prepared nanocomposite particles were
characterized by UV–vis absorption spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and N2 adsorption/desorption method at liquid nitrogen temperature (−196 °C) from Brunauer–Emmett–Teller (BET) measurements. It
is shown that at a Ag loading of 1.25 wt.% on TiO2, a high-surface area nanocomposite morphology corresponding to an average of one Ag nanoparticle per titania nanoparticle
was achieved. The diameter of the titania crystallites/particles were in the range of 10–20 nm while the size of Ag particles
attached to the larger titania particles were 3 ± 1 nm as deduced from crystallite size by XRD and particle size by TEM. Ag
recovery by photo harvesting from the solution was nearly 100%. TEM micrographs revealed that Ag-coated TiO2 nanoparticles showed a sharp increase in the degree of agglomeration for nanocomposites prepared at basic pH values, with
a corresponding sharp decrease in BET surface area especially at pH > 9. The BET surface area of the Ag–TiO2 nanoparticles was nearly constant at around a value of 140 m2 g−1 at all pH from 1–8 with an anomalous maximum of 164 m2 g−1 when prepared from a sol at pH of 4, and a sharp decrease to 78 m2 g−1 at pH of 10. 相似文献
11.
A. O. Rybaltovskii Yu. S. Zavorotnyi N. V. Minaev M. I. Samoilovich P. S. Timashev M. Yu. Tsvetkov V. N. Bagratashvili 《Russian Journal of Physical Chemistry B, Focus on Physics》2009,3(7):1106-1112
Silver-containing nanocomposites were prepared by impregnating Vycor glass (a pore diameter of 4 nm) and synthesized opal
matrices (an interstitial void size of 40 nm) with cyclooctadiene complex of silver hexafluoroacetylacetonate (Ag(hfac)COD),
a silver precursor, dissolved in supercritical carbon dioxide and were examined by optical absorption spectroscopy, atomic
force microscopy, and electron spin-resonance spectroscopy. It was demonstrated that the absorption spectra of Vycor glass
and opal matrices impregnated with Ag(hfac)COD molecules and subjected to thermal treatment in air at temperatures above 50°C
exhibit plasmon resonances characteristic of Ag nanoparticles at 420–430 nm. The peculiarities of the plasmon resonance band
for both types of samples were attributed to the morphology of the pore space in which silver particles are formed. Paramagnetic
Cu(hfac)2 molecules (copper hexafluoroacetylacetonate) were used as a spectroscopic probe for estimating the distribution of the precursor
in the pores of Vycor glass and opal matrices during supercritical fluid impregnation. 相似文献
12.
Florica Papa Catalin Negrila Akane Miyazaki Ioan Balint 《Journal of nanoparticle research》2011,13(10):5057-5064
Well-dispersed, uniform monometallic Pt and bimetallic Pt–Cu, and Pt–Ag nanoparticles protected with PVP have been synthesized
by a modified-protocol alkaline polyol method. The nanoparticles were characterized by various methods (TEM, XPS, and XRD)
to elucidate the relationship between morphology and preparation variables. The average of monodispersed nanoparticles ranged
between 4.1 and 4.9 nm. Core–shell structure was obtained in the case of bimetallic nanoparticles. The core of bimetallic
nanoparticles was found to be rich in platinum, whereas the shell contained mostly copper or silver. The final structure of
bimetallic nanoparticles was found to be determined by the morphology particles resulted in the first reduction step. Explanations
are advanced on the light of experimental results. 相似文献
13.
Ag@TiO2 core-shell structured particles of nano-size dimensions have been successfully prepared via a one-step way, which has proved quite effective in procuring stable colloids. Transmission electron microscopy (TEM) was employed to characterize the core size and the shell thickness, which typically were 20~40 nm and ~2 nm, respectively. X-ray diffraction (XRD) indicated the existence of silver. Optical absorption dependence on core size and synthetic temperature has been explored by UV–Vis absorption spectroscopy. Finally, the interesting titanium dioxide nanobubbles with silver core leached out by a unique means, were studied, which consequently proved the core-shell structure of the prepared nanoparticles, confirming the TEM observation. 相似文献
14.
I. G. Motevich N. D. Strekal’ J. W. Nowicky S. A. Maskevich 《Journal of Applied Spectroscopy》2007,74(5):666-672
We have studied the absorption, fluorescence, and surface-enhanced Raman scattering (SERS) spectra of sanguinarine using a
silver hydrosol and an electrochemical cell with a silver working electrode for different pH values in the medium. We carried
out quantum chemical calculations in order to interpret the electronic and vibrational spectra and to establish their correlations
with the structure of the molecules. We optimized the structure and determined the spectral characteristics of the cationic
and neutral forms of the sanguinarine molecules in solution and adsorbed on the surface of an anodized Ag electrode for different
potentials.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 604–609, September–October, 2007. 相似文献
15.
Doo-Hyeb Youn Seong-Hyun Kim Yong-Suk Yang Sang-Chul Lim Seong-Jin Kim Su-Han Ahn Hyo-Sun Sim Seung-Myoung Ryu Dong-Wook Shin Ji-Beom Yoo 《Applied Physics A: Materials Science & Processing》2009,96(4):933-938
This paper introduces for the first time near-field electrohydrodynamic jet printing with tilted-outlet nozzle to obtain the fine and highly conductive patterns of silver (Ag) ink. Line widths produced by near-field electrohydrodynamic
jet printing are less than 6 μm, which is approximately twenty times smaller than that of inkjet printing. Under optimized
Ag ink annealing ranges 3–9 min for 30 wt% at 150°C, we observed Ag line pattern resistivities as low as 7×10−6 Ω⋅cm. Ag ink conduction mechanisms were brought to light from microstructure analysis and post-thermal-annealing examination
of electrical characteristics. 相似文献
16.
Large third-order nonlinear optical susceptibility of Au-Al2O3 composite films near the resonant frequency 总被引:2,自引:0,他引:2
2 O3 composite films with high Au concentrations (30%–60% in volume fraction) were prepared by reactive co-sputtering and post
rapidly thermal annealing. The structure of the films and the size distributions of the Au nanoclusters were examined by TEM,
and the third-order nonlinear optical susceptibility χ(3) was measured by degenerated four-wave mixing using a 70-ps pulse laser at 532 nm. The maximum value of the χ(3) was about 1.2×10-6 esu in the annealed films and occurred at around 45% Au concentration. The figure of merit, χ(3)/α (α is the absorption coefficient), has a value of 7×10-12 esu cm over a wide range of Au concentrations.
Received: 23 July 1997 相似文献
17.
V. N. Bagratashvili N. V. Minaev A. A. Rybaltovsky A. O. Rybaltovsky S. I. Tsypina V. Ya. Panchenko Yu. S. Zavorotny 《Laser Physics》2010,20(1):139-143
The fabrication of photoand thermostable periodic structures from silver nanoparticles in polymer plates (cross-linked oligourethanemethacrylate
impregnated with silver precursors Ag(hfac) and Ag(fod) dissolved in the supercritical carbon dioxide) is studied. The process
is based on the local (depending on the irradiated spot size) photochemical decomposition of the silver precursors in the
polymer matrix that initiates the atomic aggregation and creation of silver nanoparticles with the plasmon resonance in absorption
in the spectral range 420–430 nm. The third-harmonic radiation of a Nd:YAG laser (355 nm) and the Kr+-laser (521 nm) radiation are employed for the recording of periodic structures with submillimeter and micron resolutions.
The photosensitivity of the polymer matrices impregnated with the silver precursors to the UV and visible radiation is discussed. 相似文献
18.
Garima Singhal Riju Bhavesh Kunal Kasariya Ashish Ranjan Sharma Rajendra Pal Singh 《Journal of nanoparticle research》2011,13(7):2981-2988
Development of green nanotechnology is generating interest of researchers toward ecofriendly biosynthesis of nanoparticles.
In this study, biosynthesis of stable silver nanoparticles was done using Tulsi (Ocimum sanctum) leaf extract. These biosynthesized nanoparticles were characterized with the help of UV–vis spectrophotometer, Atomic Absorption
Spectroscopy (AAS), Dynamic light scattering (DLS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR),
and Transmission electron microscopy (TEM). Stability of bioreduced silver nanoparticles was analyzed using UV–vis absorption
spectra, and their antimicrobial activity was screened against both gram-negative and gram-positive microorganisms. It was
observed that O. sanctum leaf extract can reduce silver ions into silver nanoparticles within 8 min of reaction time. Thus, this method can be used
for rapid and ecofriendly biosynthesis of stable silver nanoparticles of size range 4–30 nm possessing antimicrobial activity
suggesting their possible application in medical industry. 相似文献
19.
G. A. Martínez-Castañón N. Niño-Martínez F. Martínez-Gutierrez J. R. Martínez-Mendoza Facundo Ruiz 《Journal of nanoparticle research》2008,10(8):1343-1348
Silver nanoparticles with different sizes (7, 29, and 89 nm mean values) were synthesized using gallic acid in an aqueous
chemical reduction method. The nanoparticles were characterized using transmission electron microscopy (TEM), dynamic light
scattering (DLS), X-ray diffraction (XRD), and ultraviolet–visible (UV–Vis) absorption spectroscopy; the antibacterial activity
was assessed using the standard microdilution method, determining the minimum inhibitory concentration (MIC) according to
the National Committee for Clinical Laboratory Standards. From the microscopies studies (TEM) we observed that silver nanoparticles
have spherical (7 and 29 nm) and pseudospherical shape (89 nm) with a narrow size distribution. The sizes of the silver nanoparticles
were controlled by varying some experimental conditions. It was found that the antibacterial activity of the nanoparticles
varies when their size diminishes. 相似文献
20.
P. K. Khanna Deepti Kulkarni Rupinder K. Beri 《Journal of nanoparticle research》2008,10(6):1059-1062
Reduction of silver myristate (AgMy) under mild thermal reaction conditions in a dipolar aprotic solvent i.e. N, N-dimethylformamide (DMF) has been carried out. UV–visible absorption measurements of dried and re-dispersible brown flocculants
showed broad features of surface plasmon resonance (SPR) due to silver nanoparticles. The freshly isolated particles showed
absorption bands at 414 and 485 nm, respectively, due to inter-particle coupling or clustering of silver ions and silver atoms.
X-ray diffraction (XRD) pattern of fcc zero-valent silver resulted in crystallite size of about 10 nm. Scanning electron microscopy
(SEM) revealed formation of rod shaped silver with increasing reaction temperature. Thermal analysis (TGA) showed about 10%
weight loss due to organic capping. 相似文献