Annealing in air and vacuum were obtained glass samples Li2B4O7:Ag,Gd with Ag NPs. Three methods: the half-width strip plasmon resonance, X-ray diffraction and Small-angle X-ray scattering, in these samples by size NPs Ag. Revealed that the size of NPs Ag, defined by half-widths plasmon resonance band much smaller than obtained by other methods. It is concluded that the methods of X-ray diffraction and small-angle X-ray scattering give results closer to reality than the method plasmon resonance

Adamiv, V.T.

Demchenko, P.Yu.

Dutka, R.M.

Gamernyk, R.V.

Kulyk, Yu.O.

Teslyuk, I.M.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 4 No 1, 01NNPT03(3pp) (2015)   2304-1862/2015/4(1)01NNPT03(3) 01NNPT03-1  2015 Sumy State University Determination of Sizes of Ag Nanoparticles in Glass Li2B4O7:Ag,Gd  V.T. Adamiv1, P.Yu. Demchenko2, R.M. Dutka1,*, R.V. Gamernyk2, Yu.O. Kulyk2, I.M. Teslyuk1  1 O.G. Vlokh Institute of Physical Optics, 23, Dragomanov Str., 79005 Lviv, Ukraine 2 Ivan Franko National University, 8, Kyrylo and Methodiy Str., 79005 Lviv, Ukraine  (Received 29 May 2015; published online 27 August 2015)  Annealing in air and vacuum were obtained glass samples Li2B4O7:Ag,Gd with Ag NPs. Three methods: the half-width strip plasmon resonance, X-ray diffraction and Small-angle X-ray scattering, in these sam-ples by size NPs Ag. Revealed that the size of NPs Ag, defined by half-widths plasmon resonance band much smaller than obtained by other methods. It is concluded that the methods of X-ray diffraction and small-angle X-ray scattering give results closer to reality than the method plasmon resonance.  Keywords: Botate glasses, Ag nanoparticles, Plasmon resonance, Small-angle X-ray scattering.   PACS numbers: 61.46. – w, 64.70.ph                                                             * dutka_roman@ukr.net 1. INTRODUCTION  High attention was recently paid to metal nanopar-ticles (NPs) primarily due their property of light in-duced collective excitation of free electrons, or so-called localized surface plasmon resonance (LSPR) and also due to their extremely fast nonlinear response. Usually the LSPRs are seen in extinction spectra of metal na-noparticles embedded in a dielectric matrix as a wide band, the position of which depends on nature of the metal, the size of NPs and dielectric properties of the enviroment surrounding the nanoparticles. Bands of plasmon absorption for nanoparticles of noble metals (Au, Ag, Cu) in dielectric enviroment are observed in the visible range of spectrum, making them especially attractive for application in a variety of optical and nonlinear optical devices. Promising dielectric material for embedding of Ag nanoparticles in it is borate glass Li2B4O7, which was demonstrated in our previous paper [2]. However, some ambiguities have been documented, when determining the amount of Ag NPs, formed by annealing under re-ducing atmosphere doped with silver glass Li2B4O7:Ag. For example, it turned out, that the diameter of Ag NPs determined from atomic force microscopy falls within the range of D = 7 - 40 nm [3] with a maximum at about 14-18 nm, whereas from the half-width strips plasmon resonance it does not exceed 10 nm. At the same time, control of the size of Ag NPs in the dielectric matrix is very important, since the size of na-noparticles influences the relevant parameters of the composite Ag NPs in glass matrices. It is therefore in-teresting to perform a comparative study to determine the size of Ag NPs for the same sample, but with differ-ent techniques. After all, to determine the size of metal nanoparticles one can also use other methods such as x-ray diffraction [4] and angle x-ray scattering was [5-7]. The goal of this work is a comparative study of the size of Ag NPs in the same glass samples Li2B4O7:Ag,Gd annealed in air and vacuum, deter-mined by X-ray diffraction, small-angle X-ray scatter-ing and by the half-width strips plasmon absorption.  2. EXPERIMENTAL TECHNIQUE  For fabrication of Li2B4O7:Gd,Ag glass, lithium car-bonate Li2CO3, we use boric acid H3BO3, gadolinium oxide Gd2O3, and silver nitrate AgNO3 of high purity. The mixture of chemical reagents corresponding to the stoichiometric composition of Li2O•2B2O3 was placed in a ceramic crucible. Employing the method of multistage temperature synthesis and the following the chemical reaction:   Li2CO3 + 4H3BO3 → Li2B4O7 + СО2↑+ 6Н2О↑   the Li2B4O7 powder with Tmelt = 1198 K was obtained. Then 2 mol.% of AgNO3 and 1 mol.% Gd2O3 were add-ed. Glass was fabricated by melting the powder in an Al2O3 crucible at the temperature of 1270 K in the air environment. The melt was homogenized for 0.5 h. First, it was quenched down to the temperature of about 670 K and then left freely cooling down to room temperatures. Plates of about 10×7×1 mm3 in dimen-sion were cut out from the obtained glass, and their surfaces were ground and polished. In order to form Ag NPs, the specimens were annealed at a temperature of 710±5 K for 1–2 h in the air environment or in vacuum (<10−4 mm Hg with a titanic getter). X-ray studies of resulting composite material were conducted using X-ray complex STOE Transmission Diffractometr System STADI P and by tilted shooting (small-angle X-ray scattering) on DRON-3 diffractome-ter (Cu Kα-radiation,  = 1,5418 Ǻ). The transmission spectra were measured on a set-up created on the basis of an MDR-23 monochromator and a personal computer. An incandescent halogen lamp was used as a light source. A photoelectron mul-tiplier PMT-79 operating in the quantum counting mode played the role of a detector, which provided the linearity of signal registration in the range of 102–106.  3. EXPERIMENTAL RESULTS AND DISCUS-SION  Determination of Ag NPs was conducted by three methods.  V.T. ADAMIV, P.YU. DEMCHENKO, R.M. DUTKA, ET AL. PROC. NAP 4, 01NNPT03 (2015)   01NNPT03-2 X-ray diffraction. X-ray studies of the prepared com-posite material were conducted using X complex STOE Transmission Diffractometr System STADI P. On the diffraction pattern (Figure 1, b) registered for the glass one finds a semi-amorphous halo corresponding to max-ima of theoretically expected diffraction reflections for Li2B4O7. Pure gadolinium is not fixed, but the reflex at 38,68° 2 corresponds to the reflection from the 111 face-centered cubic lattice of pure silver. From the value of the half-width of the reflection we have estimated the size of coherent scattering domains. Assuming that the metallic nanoparticles formed during annealing are completely crystalline, the latter can be considered as an estimation for the typical size of grains in the phase.   a  b  Fig. 1 – Profiles of diffraction peak (111) Ag in samples Li2B4O7:Gd,Ag, annealed in vacuum (a) and annealed in air (b).  Comparison of diffraction for two samples annealed in vacuum and in air (Figure 1, b) shows that in these cases metal nanoparticles are formed of different sizes, such that, for glass, annealed in vacuum the coherent domain size was found to be D = 26,9 nm, whereas for glass, annealed in air it was of 7.5 nm in diameter (Ta-ble 1). The concentration of formed nanoparticles was found to be also different, namely: it appeared to be higher for annealing in vacuum and much lower when annealing in air. Small-angle X-ray scattering. For samples Li2B4O7:Gd,Ag, annealed in vacuum, the size of metal-lic nanoparticles on the surface was evaluated also by small-angle X-ray scattering (Figure 2). A standard mounted at an angle α = 3 with respect to the direction of the primary beam. Registration profile of the diffrac-tion peak (111) Ag was measured in a discrete mode with step 0,05º and exposure time of 25 sec. Technical Ag was used as the standard sample.    Fig. 2 – Profiles of diffraction peak (111) of the sample Li2B4O7:Gd,Ag, annealed in vacuum and standard technical Ag.  To determine the half-width maximums profiles they were fitted by the Lorentz function. In this case, the average size of the nanocrystals can be defined as follows: D = /( – 0)cos, where 0,  are half-width maximums for the standard and studied sample respec-tively, 2 is the diffraction angle of (111) Ag reflection. Analysis of profile maxima Ag (111) for the sample and standard gives 0 = 0.6980.020,  = 1.0520.150. After some calculations, the average size of Ag NPs was found to be D = (26.0 ± 3.0) nm (Table 1). Results obtained with the two methods of X-ray analysis for samples annealed in a vacuum lead to the same size of silver nanoparticles. We have to note that the concentration of nanoparticles in the glass, an-nealed in air was too small to obtain reliable results for sizes of nanoparticles by small-angle X-ray scattering in our experiments. The half-width of the plasmon absorption band can be used to estimate the Ag NPs sizes D: D = 2VF/Δω1/2 [8], where VF is the Fermi velocity, and Δω is the half-width of the plasmon absorption band. In metallic Ag, the Fermi velocity is VF = 1.39×106 m/s [9]. Sizes of Ag NPs appeared to be of 2.3 nm, which is much smaller (Table 1), although they are fairly well correlated with the size of 2.0 - 6.0 nm obtained for Ag NPs in various glasses by other authors [9, 10]. As shown in Table 1, there is quite a big difference in sizes of Ag NPs, determined with different methods. Moreover, the size values of Ag NPs for samples an-nealed in air and measured from the half-width of the plasmon absorption band and from X-ray diffraction differ by about 2 times, whereas for the samples an-nealed in vacuum the results are different almost by an order of magnitude. Therefore, if we take into account that the size values for annealed in vacuum sample of Ag NPs, obtained by X-ray diffraction and small-angle X-ray scattering, are practically identical (26.0 and 26.9 nm), one can accept that they are more accurate and closer to the real values than those obtained from the value of the half-width of the plasmon absorption band. The obtained by X-ray diffraction difference in sizes Ag NPs in samples annealed in air (7.5 nm) and vacuum (26.0 nm) can be explained very simply: in  DETERMINATION OF SIZES OF AG NANOPARTICLES IN GLASS LI2B4O7:AG,GD PROC. NAP 4, 01NNPT03 (2015)   01NNPT03-3 glass Li2B4O7:Gd,Ag, which is annealed in air, the Ag NPs are formed inside the matrix just under its surface (since they are not fixed Small-angle X-ray scattering method), but when annealed in vacuum the Ag NPs are formed on the top of the sample surface [11]. Since the mechanisms of Ag NPs in the same glass matrix and its surface are definitely different, the differences in sizes are quite understandable.   a  b  Fig. 3 – Absorption difference spectrum Li2B4O7:Ag,Gd glass: (а) annealed in vacuum; (b) annealed in air atmosphere. Table 1 – Dimensions Ag NPs in glass Li2B4O7:Gd,Ag, deter-mined by different methods  Annealing The method of de-termining D, nm In air atmosphere Plasmon resonance 2,8 X-ray diffraction 7,5 In vacuum Plasmon resonance 1,8÷3,0 Small-angle X-ray scattering 26,0 X-ray diffraction 26,9  4. CONCLUSION  The samples of glass Li2B4O7:Ag,Gd  Ag NPs, formed by annealing in air and vacuum were obtained.  The results of the investigations of sizes of Ag NPs by means of different methods, namely: half-width of the plasmon resonance band, X-ray diffraction and small-angle X-ray scattering, show significantly different results. It turns out that from the method of half-widths of the plasmon resonance band the Ag NPs size is much smaller than the size obtained by other meth-ods. In conclusion, the methods of X-ray diffraction and small-angle X-ray scattering give results closer to reali-ty than the method of plasmon resonance.          REFERENCES  1. K.L. Kelly, E. Coronado, L.L. Zhao, G.C. Schatz, J. Phys. Chem. B 107, 668 (2003). 2. V.T. Adamiv, I.M. Bolesta, Ya.V. Burak, R.V. Gamernyk, I.D. Karbovnyk, I.I. Kolych, M.G. Kovalchuk, O.O. Kush-nir, M.V. Periv, I.M. Teslyuk, Physica B  449C, 31 (2014). 3. I.M. Bolesta, O.O. Kushnir, I.I. Kolych , I.I. Syvorotka, V.T. Adamiv, Ya.V. Burak, I.M. Teslyuk, Adv. Sci. Eng. Med. 6, 326 (2014). 4. G.T.K. Fey, Y.D. Cho, C.L. Chen, K.P. Huang, Y.C. Lin, T.P. Kumar, S.H. Chan, Int. J. Chem. Eng. Appl. 2, 20 (2011). 5. S. Pikus, E. Kobylas, Colloids Surf. A 208, 219 (2002). 6. M.H. Oliveira Jr., P.F. Barbieri, I.L. Torriani, F.C. Marques, Thin Solid Films 516, 316 (2007). 7. A.P. Radlinski, M. Mastalerz, A.L. Hinde, M. Hainbuchner, H. Rauch, M. Baron, J.S. Lin, L. Fan, P. Thiyagarajan, Int. J. Coal Geol. 59, 245 (2004). 8. J.F. Reintjes, Nonlinear optical processes in liquids and gases (Academic Press, Orlando, 1984). 9. Yu. Kaganovski, E. Mogilko, A.A. Lipovskii, M. Rosenbluh, J. Physics: Conf. Series 61, 508 (2007). 10. A.V. Redkov, V.V. Zhurina, A.A. Lipovskii, J. Non-Cryst. Sol. 376, 152 (2013). 11. V.T. Adamiv, I.M. Bolesta, Ya.V. Burak, R.V. Gamernyk, R.M. Dutka, I.D. Karbovnyk, M.V. Periv, I.M. Teslyuk, Ukr. J. Phys. 59, 1026 (2014).  

Determination of Sizes of Ag Nanoparticles in Glass Li2B4O7:Ag,Gd

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