Synthesis and study on optical reflection and photoluminescent properties of Si[O.sub.2]/AgO nanocomposite.
Silver is a monovalent coinage metal, malleable, very ductile with a brilliant white metallic luster that can take a high degree of refinement. It has the uppermost electrical conductivity of all metals, even upper than copper, but its bigger cost has prevented it from being extensively used in place of copper for electrical purposes. While much research activity has been devoted to the optical characterization of Si[O.sub.2]/AgO nanocomposite in the visible part of the spectrum, relatively little attention has been paid to the infra-red part. [1,2,3,4] Recently several papers have been published as Ag and Ag-nanocomposite and antibacterial activity of these nanoparticles and nanocomposites [5,6,7,8,9,10].
Optical properties, especially the electrical property of Coulomb blockade, are deeply concerned with the nanoparticle state in the film such as particle size, depth distribution, density, and distance from the electrode. In general, these types of nanocomposite structures have been fabricated by depositing nanoscale metal particles onto dielectric spheres. In particular, metal-coated Si[O.sub.2] surfaces have been fabricated using such approaches as electroless deposition [11,12], surface functionalization , sputtering, layer-by-layer processing, and sonochemical deposition. These Si[O.sub.2]-coating procedures are usually complex because they involve multi-step processes that make it difficult to obtain dense, uniform nanoscale metal layers of high purity.
Today Silver nano-particles are produced with different chemical and physical methods, but what is important in the case is that in these methods, often high temperature and pressure is needed and different chemical solvents are used in order to do the reactions and stabilize nano-particles [14,15,16,17].
Several problems arise when immobilizing metal nanoparticles onto Si[O.sub.2] surfaces, including incomplete coverage, rough surfaces, non-uniformity of size and composition. This process requires the absorption of at least two photons to provide sufficient energy for the up-converted emission to occur.
Some rare earth ions, when incorporated as impurities in sufficient concentration into suitable host materials, can up-convert infrared radiation into various shorter wavelengths. This process plays an important role in enhancing optical detection and display devices. Over the past two decades, research has accumulated in search of new materials with high up-conversion efficiency. The ion implantation technique is expected as an attractive method for doping metal atoms at a certain depth in the film and forming nanoparticles with a certain size by a subsequent heat treatment [22,23,24,25].
In this paper, we have NaBH4 reducing method of silver nitrate to prepare heterogeneous silver-silica nanocomposite particles with thiol and amino groups serving to bind the Ag nanoparticles to the surfaces of the Si[O.sub.2] nanoparticles. We report optical reflection property from multiple layer structure on Si in dopte with Ag nanparticles, was studied by photoluminescence method .
2.1. Materials and Instruments:
Starting materials were obtained from Merck (Berlin, Germany) and solvents were purified by standard methods Fourier transform infrared (FT-IR) spectra were recorded on a Bruker spectrophotometer in KBr pellets. Absorbance and also photoluminescence from the prepared samples was taken by a V-570 UV and Cary 4000 systems, respectively. The surface morphology of product was characterized by using a scanning tunneling microscopy (NAMA-StM Model S[S.sub.2], NATSYCO, Iran). X-ray powder diffraction (XRD) measurements were performed using a Philips diffractometer manufactured by X'pert with monochromatized Cu Ka radiat ion. Sizes of selected samples were estimated using the Scherer method. For characterization with a scanning tuning microscope sample were gold coated.
2.2. Synthesis of Si[O.sub.2]/AgO Nanocomposite:
For synthesis of Si[O.sub.2]/AgO, nanocomposite 0.5 ([S.sub.1]), 1 ([S.sub.2]) and 1.5 ([S.sub.3]) g AgNO3 was taken to the beaker (50 ml) and added NaBH4 (4 x [10.sup.-4]). Then this component of the beaker was added to another beaker that included 100 g of Si[O.sub.2]. The whole solution was mixed 24 h; finally the compound was precipitated and separated. The product, dried at 500C for 24 h. Then the nanocomposite was taken to the electric furnace at 185 0C for 5 h until to calcination. In Si: Mp 380[degrees] C Yield: 72%. FTIR (KBr pellet, [cm.sup.-1]): 3455 (m, O-H), 1635 (w, NH), 1093 (m, B-O), 808 (s, Si-O) and 470 (s, Ag-O). UV-Vis, [lambda]max (nm)/e ([M.sup.-1] [cm.sup.-1]); 210, 310 and 360. In [S.sub.2]: Mp 380[degrees] C Yield: 65%. FTIR (KBr pellet, [cm.sup.-1]): 3462 (m, O-H), 1636 (w, NH), 1100 (m, B-O), 808(s, Si-O) and 477 (s, Ag-O). UV-Vis, [lambda]max (nm)/[epsilon] ([M.sup.-1] [cm.sup.-1]); 210, 315 and 360. In [S.sub.3]: Mp 380[degrees] C Yield: 77%. FTIR (KBr pellet, [cm.sup.-1]): 3472 (m, O-H), 1636 (w, NH), 1093 (m, B-O), 809 (s, Si-O) and 471 (s, Ag-O). UV-Vis, [lambda]max (nm)/e ([M.sup.-1] [cm.sup.-1]); 210, 310 and 380 (Figure 1). The diameter of the silica spheres was determined by scanning tuning microscopy (STM). The mean diameter of the particles was [S.sub.1]: 46 nm, [S.sub.2]: 36 nm and [S.sub.3]: 35 nm.
2.3. Characterization of nanocomposite:
X-ray diffraction (XRD) technique was used to determine the ingredients of the sample. The morphology of nanocomposite was observed using a scanning tuning microscope (STM). The obtained samples were characterized and compared via FT-IR analysis with bulk (non-nano) forms. FT-IR spectrometer at room temperature in the range from 400 to 4000[cm.sup.-1].
RESULTS AND DISCUSSION
In this investigation, a novel and simple method were developed for the synthesis of highly nanostructured, Si[O.sub.2]/AgO with NaBH4 reducing method. Silver is a widely used metal for the deposition of nanoparticles onto Si[O.sub.2] substrates. The results of the characterization of the Si[O.sub.2] nanocomposite by FTIR, UV-Vis absorption spectroscopy, XRD, STM demonstrated that fairly uniform sized nanocomposite of 35-46 nm diameter with spherical-shaped Anatase form were successfully obtained. In surveys taken from the IR spectra of Ti-O bonds were in the range of 470-800 [cm.sup.-1]. Research results indicate that with decreasing particle size to nanometer amplifier and nanocomposite construction phase to ensure proper mixing amplifier Moreover, the strength, stiffness and increases flexibility.
3.1. Electronic spectra:
Electronic spectra with comparison between [S.sub.1], [S.sub.2] and [S.sub.3] spectra's are shows in Figure 1 and Table 1. For all compounds found three special transition n [[pi].sup.*] and n [[sigma].sup.*] that so near together, these spectra are in good agreement by showing the molar ratio wavelength relation, all transitions occurred between 210 to 380 nm. For wavelength 210 nm the special transition n [[pi].sup.*] was suggested, so this character for wavelength between 310-380 nm the character n n* offered. These transition represented to the silver (metal transition) that exist in nanocomposite with Si[O.sub.2].
3.2. Characterization of structure, morphology and STM Pictures:
Room temperature powder X-Ray diffraction spectra of the product was performed to identify the crystalline phase present in the sample and shown in Figure 2. The broadening of the peaks indicated that the particles were of nanometer scale. The average crystallite size (Dc) of the Si[O.sub.2]/AgO nanocomposite was calculated using the Debye-Scherrer Equation (1) from the major diffraction peaks of the corresponding (002) and (111).
[D.sub.c] = K.[lambda]/[beta].cos[theta] (1)
Where K is a constant equal to 0.9, [lambda] is the X-ray wavelength (0.15405 nm), p is the full width at half maximum (FWHM) of the diffraction peak in radiant and 0 is the Bragg angles of the main planes. Scanning Tuning Microscope image of Si[O.sub.2]/AgO nanocomposites with different magnification for 5 hours at 185[degrees] C has been shown calcination (Figure 2). Scanning tuning microscopic observations of Ag-Ti[O.sub.2] nanocomposites shows that morphology of this nanocomposite as seen in STM pictures is mixed particles forms such as sand and ceramic. The average crystallite size of the Si[O.sub.2]/AgO nanocomposite was 35-46 nm, in agreement with that observed from STM images (Figure 3-5).
3.3. Vibrational spectra of (FTIR):
FTIR absorption was used in order to check the characteristic bands of the synthesized nanocomposites. The bonds of these compounds were at 470-800 [cm.sup.-1]. The bands at 3458, 3472 and 3448 [cm.sup.-1] were related to OH bonds in [S.sub.1], [S.sub.2] and [S.sub.3]. The spectrum shows strong IR absorption bands at 808, 470, 808, 477, 809 and 471 [cm.sup.-1] which are characteristic of Si-O and Ag-O. The spectrum shows the weak IR absorption band at 1635 and 1636 [cm.sup.-1] which is characteristic of NH in these nanocomposites.
3.4. Photoluminescence spectroscopy (PL) of Si[O.sub.2]/AgO nanocomposite:
The emission spectra of the prepared CaF2 nanoparticles were taken by a fluorescence spectrophotometer of the Cary 4000 at an excitation wavelength of 254nm. PL spectra from Si[O.sub.2]/AgO nanocomposite show (Figure 6) one UV bands at 285nm. Photoluminescence (PL) spectroscopy has extensively been used to study the optical possessions of Silisyum. We have working this technique to consider the luminescence from the Si[O.sub.2] nanocomposite samples.
In summary, the synthesis and characterization of nanocomposits have been described. We have used NaBH4 reducing method of AgNO3 to prepare heterogeneous Si[O.sub.2]/AgO nanocomposites from Si[O.sub.2] nanoparticles. These compounds were characterized by FTIR, UV-Vis, STM, Photoluminescence (PL) spectroscopy and XRD. Photoluminescence (PL) spectroscopy got widely rummage-sale to study the optical properties of Silisyum. We have working this technique to study the luminescence from the Si[O.sub.2] nanocomposite samples. The diameter of the silica spheres was determined by scanning tuning microscopy (STM). The mean diameter of the particles was [S.sub.1]: 46 nm, [S.sub.2]: 36 nm and [S.sub.3]: 35 nm. The middling crystallite size of the Si[O.sub.2]/AgO nanocomposite was 35-46 nm, in agreement with detected from STM pictures.
Received 4 September 2014 Received in revised form 24 November 2014
Accepted 8 December 2014 Available online 16 December 2014
We appreciatively acknowledge the financial provision from the Research Council of Imam Khomeini International University.
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(1) A-Lashgari, (1) Sh.Ghammamy, (2) L. Gerli and (3) G. Salgado Moran
(1) Department of Chemistry, Faculty of Science, Imam Khomeini International University, Noorozian Avenue, 3485138677, Qazvin, Iran,
(2) Facultadde Ciencias, UniversidadCatolica de la Santisima Concepcion,Concepcion, Chile
(3) Departamento de Quimica, Facultad de Ciencias Exactas, Universidad Andres Bello, Concepcion, Chile
Corresponding Author: A.Lashgari, Department of Chemistry, Faculty of Science, Imam Khomeini International University, Noorozian Avenue, 3485138677, Qazvin, Iran,
Tel: (+98) 281-8371378; Fax: (+98) 281-3780040; E-mail: email@example.com
Table 1: Electronic spectra of the SI, [S.sub.2] and [S.sub.3] nanocomposits. [[lambda].sub.1] [[lambda].sub.2] [[lambda].sub.3] (Transition character) nm [S.sub.1] 210 310 360 (n [right arrow] (n [right arrow] (n [right arrow] [[sigma].sup.*]) [[pi].sup.*]) [[pi].sup.*]) [S.sub.2] 210 315 360 (n [right arrow] (n [right arrow] (n [right arrow] [[sigma].sup.*]) [[pi].sup.*]) [[pi].sup.*]) [S.sub.3] 210 310 380 (n [right arrow] (n [right arrow] (n [right arrow] [[sigma].sup.*]) [[pi].sup.*]) [[pi].sup.*])
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|Author:||A-Lashgari; Sh.Ghammamy; Gerli, L.; Moran, G. Salgado|
|Publication:||Advances in Environmental Biology|
|Date:||Oct 1, 2014|
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