Average Size Of Ag Nanoparticles Research Articles

Green synthesis and biophysical characterization of silver and palladium nanoparticles using Laureliopsis philippiana: A potent eco-friendly larvicide with negligible impact on zebrafish (Danio rerio)

Green nanoparticles represent a sustainable and eco-friendly approach to developing larvicides targeted at controlling mosquito populations. These nanoparticles are synthesized using natural, non-toxic materials and environmentally benign processes, emphasizing their potential to combat mosquito larvae while minimizing adverse effects on the ecosystem. This approach aligns with the growing need for sustainable solutions in vector control, providing an effective alternative to traditional larvicides with reduced environmental impact. The aim of the present investigation we have utilized the leaf from Laureliopsis philippiana (LP) to synthesize silver (Ag) and palladium (Pd) nanoparticles (NPs) and studied toxicity on deadly disease vectors larvae of Aedes aegypti and Anopheles stephensi. Biosynthesized Ag and Pd NPs were extensively characterized through physical and chemical methods. Gas chromatography–mass spectrometry analysis of L. philippiana assisted in identifying the secondary metabolites of the extract's total flavonoid and phenolic compounds, which are in the reactants of the bio-reduction process during the production of NPs. The in-silico analysis was conducted on mosquito sterol carrier protein-2 (1PZ4) and mosquito odorant binding protein (2L2C). The biosynthesized Ag and Pd NPs revealed the UV absorption peak at 417 and 370 nm, and X-ray diffraction results showed the crystalline structure of NPs. At the same time, in transmission electron microscopy representation, the Ag and Pd NPs were spherical, clustered, and exhibited a noticeable average size of Ag NPs: 13.25 ± 2.53 nm and Pd NPs: 4.07 ± 1.64 nm. The biogenic Ag and Pd NPs showed concentration-dependent larvicidal mortality at 12 and 24-hour exposure with LC50 values of 29.596, 17.804, and 23.915, 14.878 µg/mL on Ae. aegypti and 23.946, 13.938, 19.457, and 12.876 µg/mL against An. stephensi, correspondingly. In-silico studies proved that Laureliopsine A and isoterpinolene showed significant docking scores compared to permethrin on mosquito proteins (1PZ4 and 2L2C). Besides, the LP-Ag and Pd NPs non-toxicity analysis was carried out on zebrafish (Danio rerio) embryos at 72 h post-fertilization. Overall, the findings clearly demonstrated the green synthesized Ag and Pd NPs from L. philippiana to develop environmentally secure and safe larvicides.

Green production of biologically active Ag and Ag–Cu nanoparticles from Prosopis cineraria pod waste extract and their application in epoxidation

The main focus of the current research is bio-nano-technologically produced nanoparticles (NPs) utilizing waste materials. There is a need for developing advanced technology to reduce waste in an eco-friendly way. Therefore, presently the discarded aqueous portion of Prosopis cineraria pod was used after boiling, to synthesize Ag and Ag–Cu NPs. FT-IR spectra illustrated the presence of phenyl propenoids and flavonoids displaying capping as well as reducing properties. TEM and SEM imaging exhibited an average size of Ag NPs (14 nm) and Ag–Cu NPs (27 nm). The crystallinity nature was confirmed by XRD, and the Cu in Ag–Cu NPs was validated through energy-dispersive X-ray analysis. According to the antimicrobial data, Saccharomyces cerevisiae displayed a zone of inhibition (ZOI) of 42.85% (Ag NPs) and 33.98% (Ag–Cu NPs) at lower concentrations (0.0321 mg/ml), while Bacillus subtilis was found most susceptible (85% ZOI) to Ag NPs at 0.5 mg/ml concentration. Further, these NPs (Ag and Ag–Cu) were utilized in the epoxidation of alkene moieties. Ag NPs showed lower conversion (65%), while Ag–Cu NPs were very active for epoxidation of linalool (93% conversion), suggesting the presence of Cu-facilitated epoxidation. To the best of our knowledge for the first time, aqueous waste is applied to prepare green NPs that can be used as antimicrobial agents and in the synthesis of platform chemicals (epoxide) for industrial aspects. These inexpensive ways of producing green NPs have been utilized several times and have found potential applications in nano-medicine, therapeutics, and modification of monoterpenoids to fine fragrance.

Assembly of Smart Microgels and Hybrid Microgels on Graphene Sheets for Catalytic Reduction of Nitroarenes

Poly (N-isopropylacrylamide-acrylic acid) [p(NIPAM-AAc)] microgel was successfully fabricated using the precipitation polymerization method. Silver (Ag) nanoparticles and graphene oxide (G) were used to fabricate the following hybrid microgels: Ag-p(NIPAM-AAc) (Ag-HMG), Ag-G-p(NIPAM-AAc) (Ag-G-HMG), and G-p(NIPAM-AAc) (G-HMG). Ag-HMG, Ag-G-HMG, and G-HMG were characterized using a Zetasizer and UV-Vis spectroscopy. The reduction of a series of different compounds with comparable and distinct chemical structures was catalyzed by synthesized Ag-HMG, Ag-G-HMG, and G-HMG hybrid microgels. The average size of Ag nanoparticles was found to be ~50 nm. Ag nanoparticles were synthesized within microgels attached to G sheets. Ag-p(NIPAM-AAc), Ag-G-p(NIPAM-AAc), and G-p(NIPAM-AAc) hybrid microgels were used for the catalytic reduction of nitroarenes and dyes. By comparing their apparent rate constant (kapp), reduction duration, and percentage reduction, the activity of HMG (hybrid microgel) as a catalyst towards different substrates was investigated. Graphene sheets play role in electron relay among Ag nanoparticles and microgels.

In English

The addition of silver ions or nanoparticles to impart antimicrobial properties to polymeric or other materials is a widely used method. However, it should be noted that the antiviral and antimicrobial effect of silver nanoparticles that come into contact with the environment, associated with their size, with a decrease in the size of nanoparticles, their effectiveness increases sharply. In the present work, we used a biodegradable polymer polylactide (PLA), which is obtained by condensation of lactic acid or ring-opening polymerization of lactide. These studies will further contribute to the development of new safe materials, in particular for food packaging, which is undoubtedly an urgent problem. The work aims is to obtain the silver-containing polymer composites based on polylactide by thermochemical reduction of Ag+ ions using natural (chitosan) and synthetic (polyethyleneimine (PEI)) polymers and to study the structure, morphology, thermomechanical and antimicrobial properties of the obtained nanocomposites. Thermochemical reduction of Ag+ ions in the bulk of polymer films, containing PLA, silver palmitate as a precursor of Ag NP and reducing agent (PEI or chitosan), has been performed by keeping them at 100–170 °C within 5 minutes. The polymeric film composites, cast from chloroform solution, were heated in an oven using precise thermal regulator VRT-3. As a result of reduction, the films get attained silver color, the Ag content in the bulk of films varied from 1 to 4 wt. %, and the thickness of the films was 110 μm. Structure, morphology, thermomechanical and antimicrobial properties of two types of nanocomposites – PLA-Ag-PEI and PLA-Ag-chitosan, formed by the thermochemical reduction of Ag+ in polymer films have been studied using wide-angle X-ray scattering (WAXS) (a DRON-4-07 diffractometer), a transmission electron microscope (TEM) (JEM-1230 JEOL, Japan), and thermomechanical analysis (a UIP-70M device). Antimicrobial activity of the obtained nanocomposites was investigated applying reference strains of opportunistic bacteria Staphylococcus aureus and Escherichia coli. It has been found that thermochemical reduction of Ag+ ions in the bulk of polymer films, when using synthetic or natural polymers (PEI or chitosan) as a reducing and stabilizing agent of silver nanoparticles occurs at 160 °C during 5 minutes. It has been found that the average size of Ag nanoparticles in the polymeric matrix is equal to ~ 7 and ~ 4 nm for PEI and chitosan, respectively. It has been shown that PLA-Ag-chitosan nanocomposites have much higher antimicrobial activity against S. aureus and E. coli strains as compared to PLA-Ag-PEI nanocomposites.

Nanocomposites based on polylactide and silver nanoparticles and their antimicrobial and antiviral applications

Novel antimicrobial and antiviral silver-containing nanocomposites (PLA-Ag-PEI) based on polylactide (PLA) have been created by the thermochemical reduction of Ag+ ions in the polymer films. Structure-properties relationships of nanocomposites were investigated using FTIR, WAXS, TEM, DSC, TGA. It was found that thermochemical reduction of Ag+ ions in presence of polyethyleneimine as a reducing agent and stabilizer occurred above 100 °C for 5 min. The optimal parameters of the Ag+ ions reduction process in the polymer films were determined, i.e. 160°С for 5 min. The average size of Ag nanoparticles in the PLA-Ag-PEI was defined to be 6.7 nm. The nanocomposites have demonstrated strong antimicrobial activity against S. aureus and E. coli strains, as well as antiviral activity against herpes simplex virus type 1, influenza A virus and adenovirus serotype 2.

Solar irradiated selective nitroaromatics reduction over plasmonic Ag-TiO2: Deposition time dependent size growth and oxidation state of co-catalyst

Solar irradiated plasmonic Ag-TiO2 (P25) nanocomposites have proficiently harvested solar energy towards nitroaromatics reduction comparatively to almost irresponsive bare TiO2. p-Nitrotoulene (p-NT) and p-nitrobenzaldehyde (p-NBAL) were potentially reduced to p-aminotoulene (p-AT, 87% and 50%) and p-aminobenzaldehyde (p-ABAL, 70% and 38%) with Ag5-P25 (5 min photodeposition time (PDT)) and Ag30-P25 (30 min PDT) respectively. The focus of this study was mainly on the role of PDT (3–30 min) which was found to be directly co-related with size, distribution and oxidation state of deposited Ag nanoparticles (NPs) over titania surface, responsible for superior photocatalytic activity. HR-TEM images confirmed the average size of Ag nanoparticles to be ∼1–2 nm and ∼7–8 nm for Ag5-P25 and Ag30-P25 respectively. Further, XPS analysis suggested the formation of ternary hybrid (Ag2O/Ag-P25) in case of 5 min PDT whereas only metallic Ag was found to be photodeposited as the times was increased to 30 min.

Ultrafast laser ablation of silver targets in miscible and immiscible liquid mixtures

• Effect of polar-polar miscible liquids on ablation. • Effect of polar-nonpolar immiscible liquids on ablation. • Influence of liquid parameters on silver nanoparticles and nanostructures. In this article we report the results obtained from ultrafast laser ablation of silver targets immersed in polar/polar miscible and polar/non-polar immiscible combinations of liquids with laser pulses of ∼2 ps duration. Former combination included acetone and water while the latter combination was toluene and water. The prepared silver nanoparticles in pure acetone, pure water (double distilled) were compared with the silver nanoparticles fabricated in acetone–water (double distilled) mixture. Similarly, synthesized silver nanoparticles in pure toluene, pure water were compared with the silver nanoparticles fabricated in toluene-water mixture. The TEM images of Ag NPs generated in acetone demonstrated that average size of Ag nanoparticles fabricated in acetone, water, and double distilled water–acetone mixture were ∼4.5 ± 1.8 nm, ∼16 ± 4 nm, and 5 ± 1.7 nm, respectively. In the case of double distilled water-toluene combination, formed silver nanoparticles were trapped inside the graphitic matrix. Obtained morphologies and average sizes of silver nanoparticles in polar/polar miscible and polar/non-polar immiscible combinations demonstrated the effect of the difference in the formatted cavitation bubble (CB). In general, products of ablation are determined by the dynamics of CB and its oscillations those depend on the intrinsic behaviour of aqueous medium of interest.

Effect of the type of reducing agents of silver ions in interpolyelectrolyte-metal complexes on the structure, morphology and properties of silver-containing nanocomposites

The objective of this work is to study the peculiarities of structural organization, morphology, thermomechanical, electrical and antimicrobial properties of nanocomposites based on pectin-polyethyleneimine interpolyelectrolyte complexes and silver nanoparticles in dependence on the type of reducing agent being applied for chemical reduction of silver ions in the interpolyelectrolyte-metal complexes. The average size of Ag nanoparticles is shown to be increased with decreasing of the activity of reducing agent (E0) and equals to 3.8 nm, 4.3 nm, and 15.8 nm, respectively, when engaging sodium borohydride (–1.24 V), hydrazine (–1.15 V) and ascorbic acid (–0.35 V). Moreover, it was found that the crystallite size of Ag nanoparticles also had the smallest value for nanocomposites obtained involving NaBH4 as reducing agent. Ag-containing nanocomposites prepared by reduction of silver ions in interpolyelectrolyte-metal complexes while applying a range of reducing agents are characterized by different electrical properties and polymer matrix’ glass transition temperature. The influence of silver nanoparticles’ size incorporated in the polymer matrix on the antimicrobial activity of nanocomposites has been established. The inhibition zone diameter of Staphylococcus aureus and Escherichia coli was higher for nanocomposites obtained using sodium borohydride and hydrazine compared to nanocomposites where ascorbic acid was used as the reducing agent.

Rebuilding supramolecular aggregates to porous hollow N-doped carbon tube inlaid with ultrasmall Ag nanoparticles: A highly efficient catalyst for CO2 conversion

Fabrication of novel heterogeneous catalysts with well-designed structures is unusually intriguing for CO2 conversion. In this study, we have prepared a porous hollow N-doped carbon tube through the pyrolysis of self-assembled melamine cyanurate aggregate supramolecular precursor. Ultrasmall Ag nanoparticles were tightly anchored in the hollow N-doped carbon tube via an in-situ fabrication. The average size of Ag nanoparticles was confined in only 2.19 nm with the assistance of abundant surface functional groups and porous structures. Additionally, inherent hollow N-doped carbon tube structure could prevent nanoparticles aggregating and leaching; also, they facilitated gas adsorption and mass transfer in CO2 catalysis. Due to their remarkable properties, the novel material was utilized as heterogeneous catalyst for the carboxylation of alkynes with CO2, and exhibited outstanding catalytic activity and stability at ambient pressure and low temperature.

Facile fabrication of silver nanoparticles deposited cellulose microfiber nanocomposites for catalytic application

In this study, we have prepared silver nanoparticles deposited cellulose microfibers (Ag-CMFs) with excellent catalytic property. The cellulose microfibers with a mean diameter of approximately 270 nm are regenerated by deacetylation of cellulose acetate microfibers. Silver nanoparticles are deposited onto the surface of the cellulose microfibers by a simple wet reduction of silver precursor using glucose as reducing agent. The morphology, thermal stability and catalytic activities of the samples have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and UV–vis spectrophotometer. The average size of Ag nanoparticles deposited on the fibers is approximately 10 ± 5 nm, and the deposition of the Ag nanoparticles does not change the morphology of the cellulose microfibers. The obtained Ag-CMFs exhibit excellent catalytic activity and reusable character for the reduction of p-nitrophenol by sodium borohydride. Therefore, the Ag-CMFs prepared by the facile method is expected to be an effective and promising catalytic material.

Thermal conductivity enhancements and viscosity properties of water based Nanofluid containing carbon nanotubes decorated with ag nanoparticles

The water based nanofluid containing carbon nanotube (CNT) decorated with Ag nanoparticles (Ag/CNT) is prepared. Its thermal conductivity (k) enhancement increases with the thermal filler loading and the decoration quantity of Ag nanoparticles. The low absolute CNT content will decrease the tangles or aggregations among the CNTs, and it will be good at the Brownian motion of CNTs in the water. It has positive effects on the thermal conductivity of nanofluid. With the increase of Ag loading, the average size of Ag nanoparticles increased, and further results in the decrease of dispersing amount of Ag/CNT as the weight of Ag/CNT is fixed. Little dispersing quantity of Ag/CNT makes it possible that the Ag/CNT particles disperse well in the fluid. So it is not easy for CNTs to form aggregation. The high intrinsic k of CNT and the effective thermal conductive networks forming by CNTs and Ag nanoparticles are good at the k enhancement. With temperature increase the k of Ag/CNT nanofluid appears improvement. The study results make it possible to develop high-efficiency nanofluid for advanced thermal management regions.

Polyoxometalate/TiO2/Ag composite nanofibers with enhanced photocatalytic performance under visible light

The exploration of highly efficient and stable visible-light-driven photocatalysts for the wastewater treatment has been recognized as one of the currently most challenging topics for the environment remediation. In this paper, we report a new type of polyoxometalate-TiO2 composite nanofibers loaded with Ag nanoparticles (NPs), labeled as PMo12/TiO2/Ag-X (PMo12=[PMo12O40]3−; X represents the weight percent (%) of Ag in PMo12/TiO2/Ag samples; X=3.98, 5.41, 6.83, and 7.19 respectively). The SEM and TEM images manifest that the average diameter of the PMo12/TiO2 composite fibers is about 130±30nm, and the average size of Ag NPs is about 15±5nm. Photocatalytic experiments confirm that PMo12/TiO2/Ag catalysts display highly efficient and durable activity for the photodegradation of methyl orange (MO) and photoreduction of Cr(VI) under visible light irradiation (λ>420nm). In these composite series, PMo12/TiO2/Ag-5.41 exhibits the highest photocatalytic activity. The photocatalytic mechanism reveals that both Ag and PMo12 can be excited under visible light irradiation, which greatly improves the visible-light absorption of the composites. Furthermore, the introduction of POM species can not only improve the light adsorption and redox activity of the TiO2, but also promote the photochemical stability of the plasmonic composites because of the relatively narrow band gap and low reversible redox potential of polyoxoanion. Such POMs-based plasmon photocatalysts are important in ongoing efforts to designing and exploring of new photocatalytic materials with low cost, high efficiency, and durability.

Silver nanoparticles encapsulated by metal-organic-framework give the highest turnover frequencies of 105 h−1 for three component reaction by microwave-assisted heating

Microwave (MW)-assisted heating, due to its unique properties has been used for synthesis of metal, oxide, zeolite, and metal-organic framework (MOF), and even to carry out organic reactions. However, less attention has been paid to integration of two or more functional components into advanced materials by MW-assisted strategy. We report herein for the first time for controllable integration of silver nanoparticles (NPs) and IRMOF-3 as a core-shell Ag@IRMOF-3 nanostructures into highly efficient catalysts by a facile one-pot MW irradiation method. Impressively, the uniform core-shell Ag@IRMOF-3 nanostructures can be fabricated as short as 5min and are highly active for three-component coupling reaction of amine, aldehyde and acetylene (A3-coupling) by MW-assisted heating strategy. Specifically, the Ag@IRMOF-3 with average size of Ag NPs of 5.2nm and IRMOF-3 of 91.5nm exhibited the highest turnover numbers and turnover frequencies of 3052 and 149,004h−1 reported up to date, respectively, for the A3-coupling reaction. Thanks to the MOF shell coating, the Ag@IRMOF-3 can be recycled at least for 8 runs without losing any activity; furthermore, the size-selective catalysis was also successfully achieved due to the size selective for propargylamines with different sizes.

The study of metal enhanced fluorescence property of Ag/ZnO composite structure

In this paper, Ag nanoparticles were successfully prepared by chemical reduction, and then Ag/ZnO composite particles were successfully prepared and deposited onto glass substrates to form Ag/ZnO thin films. Hereafter, the structure, the morphology and the metal enhanced fluorescence (MEF) property of Ag nanoparticles and ZnO/Ag composite particles were studied by XRD, SEM, EDS, TEM, UV-vis absorption and fluorescence (FL) spectrometer. The results showed that the average size of Ag nanoparticles increased with the increase of prepared time. Moreover, ZnO layer consisted of polycrystalline structure and amorphous interface layer, but nano-Ag particle was polycrystalline structure. Annealing process was carried out to investigate the influence of annealing process parameters on MEF property of Ag/ZnO composite structure. Due to annealing treatment, the amorphous component of Ag/ZnO thin films was reduced, which might improve the density of Ag/ZnO thin films and the diameter of composite particles. Furthermore, FL enhancement phenomenon of fluorescein isothiocyanate (FITC) molecules might be attributed to the joint influence of the roughness and the density of these films and the average diameter of composite particles.

The preparation and thermal performance research of spherical Ag-H2O nanofluids & applied in heat pipe

Spherical silver-water (Ag-H2O) nanofluids with good suspension (more than 85days) have been obtained via one-step method in the water phase without any surfactants or additives in the present work. The size-control technique of spherical Ag nanoparticle has been obtained through adjusting the reaction rate and the mechanism of size effect has been studied in detail. It can be found that the faster the reaction rate, the smaller the nucleation density and the smaller the particle size. The thermal conductivity of spherical Ag-H2O nanofluids were higher than H2O even the few Ag nanoparticle incorporation. Based on the preparation of Ag-H2O nanofluids, the effects of particle size, solid content and temperature on the thermal conductivity of spherical Ag-H2O nanofluids were discussed and all the measure was performed in the same condition. The conclusion can be drawn that the thermal conductivity of Ag-H2O nanofluids increases with the content of Ag nanoparticles and temperature increasing and average size of Ag nanoparticles decreasing. The effect mechanism of particle size, temperature and content of Ag nanoparticles has been studied in detail. The Ag-H2O nanofluids were determined to be the Newtonian fluid whose viscosity is close to water and the viscosity increases with the increase of the mass fraction of Ag nanoparticles. The start-up and heat transfer performance of the heat pipe using the spherical Ag-H2O nanofluids have been improved compared to the heat pipe using DI water. It is expected that the spherical Ag-H2O nanofluids with a high thermal conductivity and low viscosity are expected to be new heat transfer fluid.

The room temperature electron reduction for the preparation of silver nanoparticles on cotton with high antimicrobial activity

Functionalization of cotton by fabricating Ag nanoparticles (NPs) on cotton surface has aroused great interest for its promising applications for chemical, electronic, photonic and many other devices. Herein, a simple and rapid room temperature electron reduction, which uses argon glow discharge as the electron source, was employed to fabricate Ag NPs on cotton without using any chemical reducing agent. The color of Ag NP loaded cotton changes from light yellow to black upon the increasing Ag loading amount, while the average size of Ag NPs on the cotton barely changes from 4.4 to 6.3nm. This indicates the color change is due to the size of Ag aggregates rather than the size of single Ag NP, as demonstrated by scanning electron microscope (SEM) and UV–vis absorption analyses. The functionalized fabric exhibits high antimicrobial activity against both Gram-negative bacterium E. coli and Gram-positive bacterium B. subtilis.

Low-temperature photoluminescence behaviour of Ag decorated ZnO Nanorods

The Ag nanoparticles decorated ZnO nanorods (Ag:ZnO) were prepared by irradiating the precursor solution with ultra-violet radiation for two irradiation times (6 and 17 h). Structural and microstructural studies were done by X-ray diffraction and transmission electron microscopy, respectively. Optical properties were studied by UV-Vis spectroscopy at room temperature (300 K) and photoluminescence (PL) spectroscopy at low-temperature in the temperature range from 5 to 300 K. The Ag:ZnO nanorods possessed the wurtzite structure of ZnO along with the cubic fcc phase of Ag nanoparticles. Average size of Ag nanoparticles in Ag:ZnO nanorods prepared with 6 and 17 h of UV irradiation time was 4 and 16 nm, respectively. The 4 nm Ag nanoparticles had played a crucial role for enhanced PL emission (in the UV region) in the Ag:ZnO nanorods at 60 K. In the case of 16 nm sized Ag nanoparticles, violet emission has been enhanced about 3.5 times compared to that of pure ZnO nanorods and 4 nm-Ag:ZnO nanorods at 5 K. Thermal activation energy of 4 nm-Ag:ZnO and 16 nm-Ag:ZnO nanorods was found to be 0.6 and 0.7 meV, respectively, at low temperature region (5 to 60 K).

Large range localized surface plasmon resonance of Ag nanoparticles films dependent of surface morphology

Noble metal nanoparticles (NPs) have received enormous attention since it displays uniquely optical and electronic properties. In this work, we study localized surface plasmon resonances (LSPR) at different thicknesses and substrate temperatures of Ag NPs films grown by Laser Molecule Beam Epitaxy (LMBE). The LSPR wavelength can be largely tuned in the visible light range of 470nm to 770nm. The surface morphology is characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The average size of Ag NPs increased with the thickness increased which leading to the LSPR band broaden and wavelength red-shift. As the substrate temperature is increased from RT to 200°C, the Ag NPs size distribution becomes homogeneous and particle shape changes from oblate spheroid to sphere, the LSPR band displays sharp, blue-shift and significantly symmetric. Obviously, the morphology of Ag NPs films is important for tuning absorption position. We obtain the cubic crystal structure of Ag NPs with a (111) main diffraction peak from the X-ray diffraction (XRD) spectra. The high resolution TEM (HR-TEM) and selected area electron diffraction (SAED) prove that Ag NPs is polycrystal structure. The Ag NPs films with large range absorption in visible light region can composite with semiconductor to apply in various optical or photoelectric devices.

Effect of Ag Film Thickness on the Morphology and Light Scattering Properties of Ag Nanoparticles

Silver (Ag) nanoparticles with strong light scattering properties have been prepared on glass substrates by silver mirror reaction and annealing. The prepared silver nanoparticles have spherical shape and are well-distributed at a relatively high annealing temperature of 400 � C for silver film thickness of about 40 nm. The structures, morphologies, and light scattering properties of prepared silver nanoparticles were studied by X-ray Diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and light scattering device. As the Ag film thickness increased from 20 nm to 50 nm the average size of Ag nanoparticles increases from 130 nm to 390 nm, and the light scattering of the Ag nanoparticles has a bigger increase in the whole angle range (10 � –90 � ). Ag nanoparticles with average diameters of 320 nm have the strongest light scattering property.

Tailoring the size and distribution of Ag nanoparticles in silica glass by defects

The composites embedded with metallic nanoparticles show large nonlinear optical susceptibility and strong surface plasmon resonance absorption, which enable potential application in opto-electronics. Ion implantation has been proven to be a powerful technique of synthesis of metallic nanoparticles due to its versatility and compatibility. However, the synthesis of nanoparticles by ion implantation inevitably leads to a broad size distribution due to Ostwald ripening process. The broad size distribution has a negative effect on improving the figure of merits for nonlinear optics. In this paper, we tried to introduce defects in silica glass to act as pre-nucleation centers to mediate the size and distribution of Ag nanoparticles. In experiment, the silica glass samples were pre-irradiated by 200keV Ar ions to fluences of 0.8, 2.0 and 5.0×1016ions/cm2, and then 200keV Ag ions were implanted into the pre-irradiated samples to fluence of 2.0×1016ions/cm2. UV–VIS results show that the absorbance intensity of Ag SPR peak initially increases and then decreases with pre-irradiation fluence, which implies the change in size and density of Ag nanoparticles in samples. TEM results verify that Ag nanoparticles in the sample pre-irradiated to the fluence of 0.8×1016ions/cm2 grow bigger and distribute in a relatively narrow region comparing with that without pre-irradiation. With further increase of pre-irradiation fluence, the size of Ag nanoparticles shows a depth dependent distribution. A boundary can be clear seen at the depth of 110nm, larger Ag nanoparticles disperse in region shallower than 110nm, and smaller Ag nanoparticles disperse in the region deeper than 110nm. The average size of Ag nanoparticles initially increases and then decreases with pre-irradiation fluence. Therefore, the introduction of defects by pre-irradiation could be an effective way to tailor the size and distribution of metallic nanoparticles in matrix.