共查询到20条相似文献,搜索用时 109 毫秒
1.
Nicolas Drogat Robert Granet Vincent Sol Abdelmajid Memmi Naïma Saad Carmen Klein Koerkamp Philippe Bressollier Pierre Krausz 《Journal of nanoparticle research》2011,13(4):1557-1562
We describe a new approach to the formation of silver nanoparticles (Ag NPs) using cellulose nanocrystals. The process involves
periodate oxidation of cellulose nanocrystals, generating aldehyde functions which, in turn, are used to reduce Ag+ into Ag0 in mild alkaline conditions. The nanoparticles were characterized using transmission electron microscopy (TEM) and ultraviolet–visible
absorption spectroscopy. From the microscope studies (TEM) we observed that Ag NPs have spherical shape with a size distribution
comprise between 20 and 45 nm. The antibacterial activity was assessed using the minimum inhibitory concentration. The antibacterial
assays compare favourably with most of other experiments conducted with the same species. 相似文献
2.
Silver nanoparticles have been formed on the surface of lead crystal glass by means of (i) ion-exchange of alkaline ions from the glass by Ag+ ions from a molten salts bath, and (ii) silica based sol-gel coatings containing silver. All experimental variables concerning both ion-exchange process and sol-gel coatings application were combined and studied as main parameters governing the reduction of Ag+ ions to Ag0 atoms and further aggregation to form nanosized colloids. The content of thermoreducing agents (arsenic or antimony oxides) in the lead crystal glass was essential to favour the reduction of silver ions to form nanoparticles. Optimal experimental conditions to be used for the obtaining of surface silver nanoparticles were determined. TEM was used as the principal characterisation technique for direct observation of the nanoparticles generated. The size of silver colloids varied in the 20-300 nm range for ion-exchanged samples and in the 10-80 nm range for sol-gel coated samples. 相似文献
3.
Ling Huang Maolin L. Zhai Dewu W. Long Jing Peng Ling Xu Guozhong Z. Wu Jiuqiang Q. Li Genshuan S. Wei 《Journal of nanoparticle research》2008,10(7):1193-1202
The silver nanoparticles (AgNPs) were synthesized in an alkalic aqueous solution of silver nitrate (AgNO3)/carboxymethylated chitosan (CMCTS) with ultraviolet (UV) light irradiation. CMCTS, a water-soluble and biocompatible chitosan
derivative, served simultaneously as a reducing agent for silver cation and a stabilizing agent for AgNPs in this method.
UV–vis spectra and transmission electron microscopy (TEM) images analyses showed that the pH of AgNO3/CMCTS aqueous solutions, the concentrations of AgNO3 and CMCTS can affect on the size, amount of synthesized AgNPs. Further by polarized optical microscopy it was found that
the CMCTS with a high molecular weight leads to a branch-like AgNPs/CMCTS composite morphology. The diameter range of the
AgNPs was 2–8 nm and they can be dispersed stably in the alkalic CMCTS solution for more than 6 months. XRD pattern indicated
that the AgNPs has cubic crystal structure. The spectra of laser photolysis of AgNO3/CMCTS aqueous solutions identified the early reduction processes of silver cations (Ag+) by hydrated electron formed by photoionization of CMCTS. The rate constant of corresponding reduction reaction was 5.0 × 109 M−1 s−1. 相似文献
4.
The modification of natural clinoptilolite with silver ions using ultrasound has been investigated in the current work. The modification process was performed using clinoptilolite of different fractions (0–3.0 mm) over the temperature range of 25–55 °C, ultrasonic power range of 8.0–12.5 W and AgNO3 concentration range of 0.01–0.1 M. The zeolite modification was performed in the presence of sonication and mechanical stirring in separate runs for comparison. Fundamental analysis demonstrated that the use of ultrasound ensures desorption of air from clinoptilolite particles and accelerates the diffusion of Ag+ ions and subsequent ion exchange. Increasing the particle size of clinoptilolite led to a natural decrease in its sorption capacity. A slight increase in the sorption capacity with an increase in the equivalent particle diameter from 0.081 to 0.35 mm was seen due to changes in the structure of clinoptilolite particles during mechanical grinding. The calculated temperature coefficient of the sorption process of Ag+ ions as <1.47 means that the modification takes place with dominant control in the intradiffusion region. Increasing the power of ultrasonic irradiation did not provide a monotonous change in the sorption capacity of clinoptilolite. Increasing the concentration of argentum nitrate solution provided an increase in the content of silver ions in clinoptilolite. In general, the advantage of using ultrasonic vibrations to modify the natural clinoptilolite of different fractions with Ag+ ions was demonstrated in terms of achieving higher sorption capacity, also elucidating the effect of different operating conditions. 相似文献
5.
Chih-Kai Huang Chia-Yin Chen Jin-Lin Han Chii-Chang Chen Meng-Dan Jiang Jen-Sung Hsu Chia-Hua Chan Kuo-Huang Hsieh 《Journal of nanoparticle research》2010,12(1):199-207
The silver nanoparticles (Ag NPs) have been immobilized onto silica microspheres through the adsorption and subsequent reduction
of Ag+ ions on the surfaces of the silica microspheres. The neat silica microspheres that acted as the core materials were prepared
through sol–gel processing; their surfaces were then functionalized using 3-mercaptopropyltrimethoxysilane (MPTMS). The major
aims of this study were to immobilize differently sized Ag particles onto the silica microspheres and to understand the mechanism
of formation of the Ag nano-coatings through the self-assembly/adsorption behavior of Ag NPs/Ag+ ions on the silica spheres. The obtained Ag NP/silica microsphere conglomerates were characterized by field-emission scanning
electron microscopy (FE-SEM), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). Their electromagnetic
wave shielding effectiveness were also tested and studied. The average particle size of the obtained Ag NPs on the silica
microsphere was found that could be controllable (from 2.9 to 51.5 nm) by adjusting the ratio of MPTMS/TEOS and the amount
of AgNO3. 相似文献
6.
A. N. Latyshev O. V. Ovchinnikov D. A. Minakov M. S. Smirnov 《Journal of Applied Spectroscopy》2006,73(3):377-381
We have used photostimulated flash luminescence to study deep electronic states arising when silver ions Ag+ are deposited under high vacuum onto the surface of a ZnS single crystal, followed by creation of the conditions for neutralization
of the silver ions. The flux density of the silver ion beam was 107 cm−2·sec−1. We have observed the appearance of two types of deep electronic states with photoionization energies 1.60 eV and 1.80 eV,
arising after depositing the silver ions onto the surface of the ZnS single crystal. We have hypothesized that there may be
two different preferred sites for adsorption of silver atoms on the zinc sulfide surface. The corresponding photoionization
spectra of the adsorbed silver atoms have maxima at 775 nm and 690 nm.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 335–338, May–June, 2006. 相似文献
7.
T.V. Zashivailo 《Journal of luminescence》2009,129(12):1497-1500
The absorption, photoluminescence, and photoexcitation spectra of a number of inorganic solid solutions with a silver ion impurity have been examined. The influence of the temperature on the spectral characteristics of haloid and oxygen-containing solutions activated with Ag+ ions has been investigated. The temperature dependences of the luminescence quantum yield of solid solutions with Ag+ impurity in the temperature range 77-150 K have been studied. It is shown that the spectra under observation are conditioned by electron transition between energetic levels of Ag+ ion which are deformed because of the interaction with environment. 相似文献
8.
Yasutaka Mori Toshio Tagawa Masanori Fujita Toyohiko Kuno Satoshi Suzuki Takemi Matsui Masayuki Ishihara 《Journal of nanoparticle research》2011,13(7):2799-2806
A simple, environmentally friendly method for preparing highly size-controlled spherical silver nanoparticles was developed
that involved heating a mixture of silver-containing glass powder and an aqueous solution of glucose. The stabilizing agent
for silver nanoparticles was found to be caramel, which was generated from glucose when preparing the nanoparticles. The particle
size was independent of the reaction time, but it increased proportionally with the square root of the glucose concentration
in the range 0.25–8.0 wt% (corresponding to particle sizes of 3.48 ± 1.83 to 20.0 ± 2.76 nm). Difference of the generation
mechanism of silver nanoparticles between this inhomogeneous system and a system in which Ag+ was homogeneously dispersed was discussed. 相似文献
9.
S. Padovani D. Puzzovio C. Sada P. Mazzoldi I. Borgia A. Sgamellotti B.G. Brunetti L. Cartechini F. D’Acapito C. Maurizio F. Shokoui P. Oliaiy J. Rahighi M. Lamehi-Rachti E. Pantos 《Applied Physics A: Materials Science & Processing》2006,83(4):521-528
It has recently been shown that lustre decoration of medieval and Renaissance pottery consists of silver and copper nanoparticles dispersed in the glassy matrix of the ceramic glaze. Here the findings of an X-ray absorption fine structure (XAFS) study on lustred glazes of shards belonging to 10th and 13rd century pottery from the National Museum of Iran are reported. Absorption spectra in the visible range have been also measured in order to investigate the relations between colour and glaze composition. Gold colour is mainly due to Ag nanoparticles, though Ag+, Cu+ and Cu2+ ions can be also dispersed within the glassy matrix, with different ratios. Red colour is mainly due to Cu nanoparticles, although some Ag nanoparticles, Ag+ and Cu+ ions can be present. The achievement of metallic Cu and the absence of Cu2+ indicate a higher reduction of copper in red lustre. These findings are in substantial agreement with previous results on Italian Renaissance pottery. In spite of the large heterogeneity of cases, the presence of copper and silver ions in the glaze confirms that lustre formation is mediated by a copper- and silver-alkali ion exchange, followed by nucleation and growth of metal nanoparticles. 相似文献
10.
D. M. Popolan T. M. Bernhardt 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(2):251-254
The reactions of free, size selected Au
n
+
(n = 1–3, 5, 7) and Ag3
+
clusters with CH3Br as well as the photodissociation of the resulting complexes
at 266 nm were studied in a radio frequency ion trap under multiple collision conditions.
CH3Br was found to interact more strongly with the gold clusters than with
the silver clusters. All investigated metal clusters exhibited characteristic size
dependent adsorbate coverages. Furthermore, the successive loss of methyl radicals was
identified as a major thermal reaction channel of the adsorbed CH3Br molecules.
Photodissociation experiments were performed with the product complexes of the trimer
clusters and revealed the strongly preferred light-induced fragmentation of
Au3Br3
+
and Ag3Br3
+,
respectively, over any other thermal reaction products. However, whereas in the case of
the gold cluster complexes the bare Au3
+
was exclusively re-formed through laser irradiation, considerable photoinduced metal
cluster fragmentation occurred in the case of
Ag3Br3
+. 相似文献
11.
Ramasamy Rajesh Kumar Krishnamurthy Poornima Priyadharsani Kaliannan Thamaraiselvi 《Journal of nanoparticle research》2012,14(5):860
In this study, an environmental friendly process for the synthesis of silver nanoparticles (AgNPs) using a fungus Aspergillus tamarii has been investigated. The process of silver ion reduction by the fungal extracellular filtrate was spontaneous which lead
to the development of an easy process for synthesis of silver nanoparticles. The AgNPs formed were characterized using UV–Visible
spectrum, FTIR, and SEM. The results revealed that silver ions reduction by the fungal extracellular filtrate started at 420 nm
after 0.5 h of incubation time. The FTIR peaks were observed at 1393, 1820, 2727, and 3545 cm−1. The SEM result showed the distribution of spherical AgNPs ranging from 25 to 50 nm. 相似文献
12.
This study presents a two-step synthesis of nanoparticles and the stabilization process of Ag ions in the matrix of NaCl nanocrystals. Ag+ ions are incorporated to NaCl with a new and attractive method that can be easily used for the different types of alkaline halides. The nanoparticles with predominant size found between 10 and 15 nm were stabilized on the surface and/or interior of NaCl nanocrystals using, in the first stages, the ionic-exchange property of zeolite A4. The optical properties of the materials were characterized through optical absorption, leading to well defined absorption bands located in the wave length values between 217–275 nm and 350–770 nm approximately, for Ag+ and AgNp, respectively. The antibacterial property of Ag ions and nanoparticles stabilized in NaCl was analyzed against gram-negative Escherichia Coli and Klebsiella bacteria. In order to quantify the antibacterial effect of Ag ions and nanoparticles the inhibition ratio was used as a parameter on the bacteria colonies grown in culture medium by conventional methods. Ag+ ions that were stabilized in NaCl nanocrystals show a mayor inhibition ratio in contact with Klebsiella bacteria, conversely Ag nanoparticles showed better results in contact with E. coli. 相似文献
13.
Glasses containing silver, tin and europium were prepared by the melt-quenching technique with silver nanoparticles (NPs) being embedded upon heat treatment (HT). An intensification of Eu3+ ions emission was observed for non-resonant excitation around 270 nm, corresponding to UV absorption in the material. Optical measurements suggest that light absorption occurs at single Ag+ ions and/or twofold-coordinated Sn centers followed by energy transfer to europium which results in populating the 5D0 emitting state in Eu3+. After HT at 843 K, a quenching effect is observed on Eu3+ luminescence with increasing holding time in the 350–550 nm excitation range. The quenching effect shows with the presence of Ag NPs which may provide multipole radiationless pathways for excitation energy loss in europium ions. 相似文献
14.
N. Hori A. Furuya M. Tsuruta F. Misaizu K. Ohno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):41-44
Photoinduced dissociation in the ultraviolet region has been investigated for Ag nF n-1
+ cluster ions. Photodissociation spectrum of
Ag2F+
in the energy of 3.8–5.6 eV exhibits several sharp bands corresponding to the transition to electronically excited states.
In this dissociation, only the Ag2
+ ion was observed as a fragment ion. Theoretical calculation indicates that the parent Ag2F+ ion has a linear Ag-F-Ag equilibrium geometries in the ground and excited states. Since conformational changes by excitation
of bending vibration are necessary for the fragmentation of an F atom, this indicates that production of Ag2
+ from Ag2F+ is a result of internal conversion and following conformational changes. 相似文献
15.
Metastable fragmentation of silver bromide clusters 总被引:2,自引:0,他引:2
J.-M. L'Hermite F. Rabilloud L. Marcou P. Labastie 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):323-330
The abundance spectra and the fragmentation channels of silver bromide clusters have been measured and analyzed. The most
abundant species are AgnBrn - 1
+ and AgnBrn + 1
- and Ag14Br13
+ is a magic number, revealing their ionic nature. However, some features depart from what is generally observed for alkali-halide
ionic clusters. From a certain size, AgnBrn - 1
+ is no more the main series, and AgnBr n - 2, 3
+ series become almost as important. The fast fragmentation induced by a UV laser makes the cations lose more bromine than
silver ions and lead to more silver-rich clusters. Negative ions mass spectra contain also species with more silver atoms
than required by stoichiometry. We have investigated the metastable fragmentation of the cations using a new experimental
method. The large majority of the cations release mainly a neutral Ag3Br3 cluster. These decay channels are in full agreement with our recent ab initio DFT calculations, which show that Ag+-Ag+ repulsion is reduced due to a globally attractive interaction of their d orbitals. This effect leads to a particularly stable trimer (AgBr)3 and to quasi-planar cyclic structures of (AgBr)n clusters up to n = 6. We have shown that these two features may be extended to other silver halides, to silver hydroxides (AgOH)n, and to cuprous halide compounds.
Received 9 November 2000 and Received in final form 25 January 2001 相似文献
16.
A. L. Stepanov R. I. Khaibullin V. F. Valeev Yu. N. Osin V. I. Nuzhdin I. A. Faizrakhmanov 《Technical Physics》2009,54(8):1162-1167
A method is described for the ion synthesis of silver nanoparticles in epoxy resin that is in a viscousfluid state (viscosity
30 Pa s) during irradiation. The viscous-fluid or glassy polymer is implanted by 30-keV silver ions at a current density of
4 μA/cm2 in the ion beam in the dose range 2.2 × 1016–7.5 × 1016 ions/cm2. The epoxy layers thus synthesized contain silver nanoparticles, which are studied by transmission electron microscopy and
optical absorption spectroscopy. The use of the viscous-fluid state increases the diffusion coefficient of the implanted impurity,
which stimulates the nucleation and growth of nanoparticles at low implantation doses and allows a high factor of filling
of the polymer with the metal to be achieved. 相似文献
17.
Nanoparticles of two silver(I) coordination polymers (CPs), [Ag2(L1)2(DCTP)]n (1) and [Ag2(L2)(DCTP)]n (2) (L1 = 1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, L2 = 1,4-bis(benzimidazol-1-yl)-2-butene, H2DCTP = 2,5-dichloroterephthalic acid), were synthesized by the sonochemical approach and hydrothermal method. Both CPs were characterized by elemental analysis, IR spectra, single-crystal X-ray diffraction, scanning electron microscopy (SEM), and thermogravimetric analyses (TGA). CP 1 exhibits a 2D 4-connected sql net with the point symbol {44.62}. While CP 2 displays a 2D 3,4-connected 3,4L13 net with the point symbol {4.62}2{42.62.82}. The structural diversity indicates that semi-rigid bis(benzimidazole) co-ligands play important roles in tuning the structures of the mixed Ag(I) CPs. The ultrasound irradiation time, temperature, and power showed significant effects on the morphology and growth process of the nanoparticles of two silver(I) CPs. The luminescence and photocatalytic properties of the nanoparticles of CPs 1–2 on the degradation of methyl blue (MB) were also investigated in detail. 相似文献
18.
Akira Doi 《Journal of Physics and Chemistry of Solids》2005,66(6):1091-1100
Comparison was made between crystals of thallium chloride and silver chloride on their biasing effects with dc/ac voltage. Previous reports say that, although their electrical conductivities are similar, the dominant charge carriers in the former are the Cl− ions while the Ag+ ions in the latter. The present dc/ac study demonstrates the following: for thallium chloride, although Cl− conduction may be dominant under low bias field, Tl+ conduction supercedes Cl− conduction when the bias field is enhanced. For silver chloride, Ag+ conduction is overwhelming within wide temperature range, to cause easy dielectric breakdown on dc biasing. Concerning the extrinsic conductivity seen at temperatures below 60 °C (thallium chloride) or below 150 °C (silver chloride), it is ascribed to grain-boundary related electron conduction, not to grain-boundary related Tl+ or Ag+ conduction as reported earlier. 相似文献
19.
H. Nagao K. Awazu S. Hayakawa K. Iwamoto M. Toyoda T. Ichihara 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):279-287
Various dissociation channels of silver bromide cluster ion
Ag2Br+ and silver cluster ion Ag3
+ were observed in
high-energy collisionally-activated dissociation (CAD) using a Cs target.
The fragment patterns of the high-energy CAD were compared with those of the
metastable dissociation and low-energy CAD. The difference in the fragment
patterns between the high-energy CAD and the other dissociation methods was
explained in terms of the internal energy distributions. The dissociation
mechanisms of neutral silver bromide cluster Ag2Br and silver cluster
Ag3 were also investigated by charge inversion mass spectrometry using
the Cs target. While the fragment ions AgBr- and Ag2
- were
dominantly observed in the charge inversion spectrum of Ag2Br+,
the undissociated ion Ag3
- was observed as a predominant peak in
the case of Ag3
+. The dissociation behavior of Ag2Br*
can be explained on the basis of the calculated thermochemical data.
Contrary to this, the predominant existence of the undissociated
Ag3
- cannot be explained by the reported thermochemical data. The
existence of undissociated Ag3
- suggests that the dissociation
barrier is higher than the internal energy of Ag3
*
(theoretical: 1.03 eV, experimental: 2.31 eV) estimated from the ionization
potentials of Ag3 and Cs. 相似文献
20.
《Current Applied Physics》2019,19(11):1187-1194
A seed-mediated growth method was commonly applied to prepare one-dimension nanomaterials. However, some associated particles were unavoidable in the formation of target nanoparticles. Herein, we reported a modified method to prepare silver nanotriangles with higher uniform shape and particle size. The size and morphology of the formed nanoparticles could be controlled by regulating reaction conditions. The results showed that cetyl trimethyl ammonium bromide (CTAB) concentration and seed concentration were related with both the morphology and the particle size. The NaOH concentration, AgNO3 concentration, and the mole ratio of Vc/Ag+ mainly affected the particle size of the formed nanotriangles. The formation of silver nanotriangles may be due to the selective stacking of the new tiny nanoparticles and the oriented growth of silver seed crystals. The oxidizing action of Br−/O2 existing in the CTAB system should be responsible for the final morphology of truncated triangular silver nanoplates. 相似文献