Influence of the size of gold nanoparticles dispersed in glass matrix on optical properties

Journal Pre-proof Influence of the size of gold nanoparticles dispersed in glass matrix on optical properties Shivani Singla, Venu Gopal Achanta, Om Prakash Pandey, Gopi Sharma PII:

S0272-8842(19)33769-1

DOI:

https://doi.org/10.1016/j.ceramint.2019.12.267

Reference:

CERI 23920

To appear in:

Ceramics International

Received Date: 24 October 2019 Revised Date:

15 December 2019

Accepted Date: 30 December 2019

Please cite this article as: S. Singla, V.G. Achanta, O.P. Pandey, G. Sharma, Influence of the size of gold nanoparticles dispersed in glass matrix on optical properties, Ceramics International (2020), doi: https://doi.org/10.1016/j.ceramint.2019.12.267. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Ltd.

Influence of the size of gold nanoparticles dispersed in glass matrix on optical properties Shivani Singlaa,b, Venu Gopal Achantac, Om Prakash Pandeya, Gopi Sharmab,* a

Functional materials lab, School of physics and materials science, Thapar Institute of Engineering and Technology, Patiala, 147004, India b

Department of physics, Kanya Maha Vidyalaya, Jalandhar, Punjab, 144004, India c

DCMP&MS, Tata Institute of Fundamental Research, Mumbai, 400005, India

* Corresponding author: e-mail: [email protected], Phone: +919888014241 Abstract: Glasses containing noble metal nanoparticles (MNPs) are in demand for optical switching devices because of their large third-order nonlinear optical coefficients associated with the localized surface plasmon resonance (LSPR) of metal nanoparticles. While the MNPs can be chosen based on the operation wavelength as the geometry of the MNP governs the LSPR, efforts are on to develop glasses having a uniform distribution of particles in its matrix. In this paper, we report the MNP doped glass preparation and their properties. Bismuth borate glass with a molar composition of 35-Bi2O3:65-B2O3 and also gold nanoparticles (GNPs) of different sizes (10 nm, 40 nm and 100 nm) dispersed in these glasses are prepared using conventional melt quench technique. X-ray diffraction (XRD) is carried out to study the modification in structure with the variation in the size of the GNPs. Morphological studies have been carried out using Field Emission Scanning Electron Microscopy (FESEM) and the variation in the thermal stability of the prepared system has been observed using Differential Thermal Analysis (DTA). Prepared samples are characterized by Uv-Vis spectroscopy, ellipsometry and Z-scan to study the linear and nonlinear optical behaviour of the material. From ellipsometry results, the refractive index in the UV-VIS-NIR region is estimated and it is found to increase with the increase in particle size. The nonlinear optical properties were studied using the Z-scan technique with a Ti: 1

sapphire laser at 800 nm and nonlinear parameters (nonlinear absorption and nonlinear refractive index) is obtained after fitting the experimental data. Keywords: Different sizes, nanoparticles, glass, Z-scan

2

1. Introduction: In the present era, the dielectric media like glass containing metallic nanoparticles (MNPs) are being investigated intensively because the presence of MNPs significantly influences the linear and non-linear susceptibilities of the host matrix with enhanced emission efficiency [1– 6]. It was shown that the random fractal distribution of MNPs results in giant fluctuation in the local electromagnetic field [7]. Thus, glasses having a uniform distribution of MNP in its matrix would be useful in various fields like solar energy conversion, optical data storage, photonics, biomedical [8–11]. Among all the noble metal nanoparticles, gold nanoparticles (GNPs) have been extensively studied. The linear and nonlinear optical properties of GNPs make them unique as these properties are not found in the bulk gold [12–14]. Strong enhancement in the thirdorder nonlinear optical susceptibility (χ(3)) has been observed in materials containing GNPs around the peak localized surface plasmon resonance (LSPR) that makes them more interesting to investigate [10]. Moreover, the ultrafast nonlinear response of the GNPs embedded glasses makes them potential candidates for optical waveguides, ultrafast optical switches, waveguide lasers and optical storage [15–18]. However, these properties depend on the size of the GNPs dispersed inside the glass matrix. The origin of LSPR is attributed to the collective oscillation of conduction electrons at the surface that is induced by the interaction with the incident electromagnetic field [19]. The LSPR bandwidth is highly dependent on the size and shape of GNPs [20,21]. Apart from these, other properties like colour, melting point, the surface to volume ratio etc. also show a significant dependence on the size of the GNPs [18,22]. In order to realize materials with large optical nonlinearity, the choice of the dielectric medium is very important. Among all the glass-forming materials, Boric oxide is the most

3

important and attractive glass former because of the remarkable property of its network. It can easily accommodate different network formers/modifiers in its network [23]. These glasses show glass-forming ability which is highly composition dependent i.e. largely depends upon the glass former/modifier chosen [24]. The boron atoms in their glasses are generally coordinated with either three or four oxygen atoms forming [BO3] and [BO4] structural units which further combine to make higher structural units called pyroborate, metaborate etc. The addition of Bismuth oxide in the borate allows the control of optical, thermal and structural properties depending upon the composition used [25]. Metal nanoparticles have a lower melting point compared to bulk. Thus, it would be difficult to get MNPs embedded in glasses that need to be prepared at high temperatures. Bismuth reduces the melting point of the borates and thus such low melting point glasses would be an ideal choice for preparing glass-GNP composites. Several attempts have been made to detect the behavior of GNPs in various glassy systems in the past. Ashok et al.[26] recently reported the structural and physical characteristics of Au2O3 doped sodium antimonite glasses and found that the synthesized glasses are highly suitable for sub-wavelength optoelectronic devices. Our earlier study clearly indicates that such glasses have a very high refractive index in the THz region and can be used to control the dispersion [27]. The present work is devoted to checking the influence of the size of the GNPs on the structural, thermal, morphological and nonlinear optical properties so that one can choose the appropriate size for a particular application. 2. Experimental details: Using the conventional melt quenching technique, the base glass having composition of Bi2O3 : B2O3 :: 35% : 65% was prepared along with the samples containing 3 x 108 number of GNPs of 10 nm, 40 nm and 100nm size GNPs (Sigma Aldrich, particles suspended in 0.1 mM of phosphate-buffered saline (PBS)). Table 1 gives the details of the sample 4

compositions chosen for the present study. In order to prepare the glasses, the required amount of the glass constituents were taken in a mortar and mixed properly with the help of a pestle for approximately 30 minutes. After that, the mixture was transferred to alumina crucible and placed in the muffle furnace. The temperature of the furnace was raised to 850 o

C and at this temperature, the crucible containing the mixture is kept for 15 min to ensure

complete melting. Finally, the molten glass was poured on a preheated mold and placed in an annealing furnace at 350 oC for two hours. Photographs of these glasses obtained after cutting and polishing are shown in Fig. 1. X-ray diffraction (XRD) study was performed using Panalytical Xpert Pro MPD in which Cu Kα radiation, equipped with Xcelerator Detector with diffracted beam monochromator to observe the diffraction peak was used. In order to carry out morphological studies, Field Emission Scanning Electron Microscopy (FESEM) has been performed using Zeiss Ultra 55. Thermal properties of the prepared glasses were studied using differential thermal analysis (DTA) with the temperature sensitivity of ±1 oC (NETZSCH DSC 404F3). DTA data was recorded by heating 50 mg of fine glass powder in alumina crucible from 30 oC to 1000 oC at a constant heating rate of 10 K/min by taking N2 as purging gas. Optical transmission study at room temperature in the range of 200-800 nm was done using the Cary5000 UV-VIS-NIR spectrometer. The study of both linear and nonlinear refractive indices was carried out on the synthesized glasses. Linear refractive index at room temperature in the wavelength range of 280-1680 nm was measured using Woollam spectroscopic ellipsometer M-2000. The nonlinear refractive index and nonlinear absorption coefficient of glass samples were determined using closed aperture (CA) and open aperture (OA) Z-scan measurements, respectively. For Z-scan measurements, 100 femtosecond pulses at 800 nm central wavelength (Spectra Physics, Tsunami) having Gaussian spatial distribution were focused using a 10 cm focal length plano-convex lens and the sample was

5

moved along the Z-axis (beam axis) through the focal region with the help of a programmable linear stage (Newport). The moving sample experiences different laser intensities (maximum at the focal region that progressively decreases as the sample moves on either side of the focal plane). The variation in the transmitted laser intensity is recorded using a photodiode as a function of the sample position. The CA measurements were recorded with an aperture in front of the diode whereas no aperture was present in the case of OA measurements. The Z-scan theory discussed by Mansoor Sheik-Bahae et al. [28] has been used to fit the experimental data and to calculate the nonlinear coefficients (refractive index and absorption coefficient). 3. Results and Discussion: 3.1. X-ray Diffraction: Fig. 2 shows the X-ray diffraction pattern of the present glass systems with no detectable sharp peaks. The presence of two broad peaks centered at 27o and 45o shows the existence of short-range ordering in the synthesized materials and hence confirms its glassy nature. The increased scattering due to larger GNPs was seen in BiB40 and BiB100 samples. 3.2. FESEM: In order to investigate the morphology of different sized GNPs inside the glass matrix, FESEM images are recorded and are shown in Fig. 3 (a-d). Fig. 3 (a) is the image of the bare glass (BiB) and shows the glass matrix only. Fig. 3 (b-d) show the presence of gold nanoparticles in the glass matrix. Particle size calculated from Fig. 3 (b), 3 (c) and 3 (d) are 45 nm, 78 nm and 200 nm for the samples BiB10, BiB40, and BiB100, respectively. In order to calculate the particle size, the obtained FESEM micrographs containing AuNPs were first magnified and then were analyzed using ImageJ software. This was done on several images taken at different magnifications and at several locations on the samples. It may be observed

6

that the observed particle size is bigger in comparison to the initially added GNPs. While melting the batch, high temperature results in splitting of GNPs into Au0 atoms that are highly unstable in nature. Au0 atoms further start interacting with other Au0 atoms and results in the formation of bigger sized GNPs. This whole process may not take place while melting only but extends during the annealing of the glass. The particle size can be controlled by using a refractory material along with stabilizers like rare earths along with the nanoparticles or by using coated nanoparticles instead of bare GNPs [29]. Moreover, this variation in particle size results in sample color change as evidenced from Fig. 1. 3.3. DTA: Fig. 4 displays the thermogram of the prepared glass samples. In these curves, the thermal parameters like glass transition temperature (Tg), onset crystallization temperature (Tx), peak crystallization temperature (Tp), melting points (Tm) and thermal stability factor (∆T = Tx Tg) have been marked and given in Table 2. It is observed that the addition of GNPs (of any size) leads to the appearance of two crystallization peaks which directly points to the existence of phase separation [30]. While melting the glass, GNPs coagulate to form bigger GNPs as can be seen in Fig. 3. The addition of GNPs has led to phase separation. Whereas, no such phenomena occur for base glass BiB because of the absence of GNPs. It can be clearly seen that with the addition of GNPs, Tg for the glass decreases. Lower the Tg more will be the coagulation [31]. Moreover, the bigger sized GNPs further decrease the Tg because of the shielding effect as reported in our previous work [27]. No remarkable effect on the glass melting point has been observed. The thermal stability factor is an important parameter to determine the working range for fiber drawing [32]. Larger the difference in Tx and Tg greater will be the resistance to crystallization [33]. For all the prepared samples, ∆T is greater than 100 oC and hence the fabricated glasses are highly suitable for fiber drawing

7

applications [34]. From Table 2, it is observed that ∆T decreases with the addition of GNPs and hence the thermal stability gets decreased i.e. nucleation could take place more rapidly. 3.4. UV-Vis Spectroscopy: Transmission spectra of the prepared glass sample are taken in the region of 200-900 nm and are displayed in Fig. 5. It is clear from Fig. 4 that glasses show effective transparency in the visible region. Whereas, no surface plasmon resonance peak corresponding to the GNPs is observed because of its low content as well as much larger size due to coagulation as seen from FESEM images. The observed peak at 465 nm is attributed to the presence of Bi in the glass matrix [35]. The negligible effect of GNPs is observed on the percentage transmission of the glass. 3.5. Ellipsometry: Ellipsometry helps measure the dispersion (wavelength-dependent refractive index) of the material. The procedure illustrated by Singla et al. [27] has been followed to estimate the refractive index. Cauchy’s model, given below, is used to fit the ellipsometry data and obtain the dispersion:

n(λ) = a +

+

; k = kamp.e(E-band_edge),

(1)

where, a, b and c are variable fit parameters that determine the index dispersion, k amplitude (kamp) and exponent (E) are fit parameters that determine the shape of the extinction coefficient dispersion and band edge parameter is taken to be 400 nm (it is not a fit parameter since it is directly related to kamp). The fitting is done to achieve the least mean square error (MSE) value and the obtained parameters are displayed in Table 3. It is observed from Fig. 6 that the refractive index increases with the addition of GNPs that further increases with the increase in the size of GNPs. This dependence of the refractive index on the GNPs is

8

attributed to the formation of highly polarizable non-bridging oxygens in the glass [36]. Glasses with a high refractive index are suitable for the fabrication of long-range surface plasmon resonance sensors [37]. 3.6. Z-scan: The Z-scan technique is a highly sensitive approach for the determination of the sign and the value of the third-order optical nonlinearity (TON). Z-scan measurements are carried out here on the fabricated material to measure nonlinear absorption coefficient (NA) and nonlinear refractive index (NR). In this technique, the variation in the transmitted laser intensity is measured as a function of the sample position, as it moves across the focal point. Measurements have been carried in closed-aperture (CA) and open-aperture (OA) Z-scan configurations. OA Z-scan configuration has a contribution from NA whereas CA Z-scan has contributions from both NA and NR. TON is mainly classified into two groups: resonant and non-resonant. Real transitions result in resonant nonlinearities whereas virtual transitions give rise to non-resonant nonlinearities. In the present study, nonlinear measurements are carried out at non-resonant wavelength (800 nm). In a typical Z-scan experiment, the examination of existing nonlinear phenomena is done on the basis of transmission response. An increase in transmission at the focal point (Z = 0) in OA Z-scan is attributed to saturable absorption (SA) whereas the decrease in the transmission is credited to reverse saturable absorption (RSA). In Fig. 7 (a), signatures of OA Z-scan data taken for all the samples are displayed. OA Z-scan curves of all the samples comprise of a valley at Z = 0 confirming the existence of RSA. Moreover, the calculated values of hν/Eo for all samples lies between 0.5 and 1. According to the theory of nonlinearity given by Sheik Bahae et. al. the origin of RSA in such cases is two-photon absorption (2PA) induced by 9

electronic transitions of Bi3+ [38,39]. The values of the 2PA coefficient are calculated by fitting the experimental data (shown by the solid square in Fig. 7 (a)) using the following equation: T (Z, S=1) =

√

[

( ⁄

(2)

,

) ]

where T(Z) is normalized transmittance, β is coefficient of 2PA, Io is peak intensity at Z = 0, Z is the position of the sample with reference to the focus, Zo = kwo2/2 is Rayleigh range for the laser beam, k = 2π/λ is wave factor, wo = spot size at focus (radius at 1/e2), Leff = (1 – exp (-αL))/α where L is the sample thickness and α is the coefficient of absorption. Data fits well with the 2PA theory (shown by the solid line in Fig. 8(b)) and hence supports the existence of the 2PA process. The values of the 2PA coefficient obtained after fitting (displayed in Table 4) are observed to decrease with the addition of GNPs. This decrease in the 2PA coefficient is attributed to the suppression of electronic transitions after the addition of GNPs in the glass. The suppression further increases with the increase in the size of the GNPs and hence results in a decrease in the 2PA coefficient with the increase in the size of added GNPs. Xu et al. [39] reported that the enhancement in TON in MNP doped glasses is dependent on LSPR and excitation wavelength. For non-resonant excitation, the free electrons with insufficient energy get trapped in the energy states that lead to the blocking of 2PA caused by electronic transition [40]. This blocking increases with the increase in size and hence results in a decrease in 2PA. Prepared glasses show higher β value than other glass system Au glass (2.16 × 10-13 m/W) [41], Au/NiO glass (6.70 × 10-13 m/W) [41], AuNPs doped 5Na2O-20B2O3-75SiO2 ( 6.5 × 10-13 m/W) [42], Na2O–B2O3–SiO2 containing CuNPs (4.1 × 10-13 m/W) [43] and GB-Au (5 × 10-16 m/W) [44]. The sufficiently high value of β indicates the good optical limiting behaviour of the material [6].

10

Fig. 7 (b) displays the CA Z-scan data with features of a valley followed by a dip which indicates the existence of a positive type of nonlinearity and the lensing effect leading to selffocusing. In order to calculate the nonlinear refractive index (n2), the CA Z-scan data is fitted using the following equation [45]: T1 (Z, S ≈ 0) = 1 +

( ⁄ (

( ⁄

) )(

) ( ⁄

(3)

,

) )

where φ0 is the fitting parameter and represents the phase difference related to the thirdorder nonlinearity. After substituting the fitting parameter to equation (4), the value of n2 is obtained and is reported in Table 4, n2 =

(4)

.

In Fig. 7 (b), the obtained CA Z-scan experimental values are represented by solid squares whereas the theoretical fit, done using equation (3), is shown using a solid line. It is clearly observed that theory fits well with the data and the third-order nonlinearity increases with the increase in the particle size of nanoparticles inside the glass. Further, the separation between dip and peak position is calculated to be 1.7 Z0 that validates the existence of nonlinearity with an ultra-fast response due to a purely electronic process [38]. The increase in nonlinear refractive index with the addition of gold is attributed to the enhanced local electric field due to surface plasmon resonances. The condition for TON material suitable for all-optical switching applications is represented as follows [46]: =

" #$% &

(5)

>1

(6)

' = " < 1

where Imax is the threshold damage intensity for the glassy material. No damage is observed in any of the samples even at the maximum input intensity. Also, the linear absorption coefficient (α) is small for the samples and hence Eqn. (5) is satisfied. The calculated values 11

of T are displayed in Table 4 and it is depicted that the T values are lower for the GNPs containing samples as compared to the bare glass. Moreover, it is clear that the glassy material becomes more appropriate for optical switching devices as the particle size increases. 4. Conclusion: In the present study, a glass of composition 35%Bi2O3 : 65%B2O3 dispersed with 3 x 108 number of different sizes (10, 40 and 100 nm) GNPs are prepared. Following are the salient features of the prepared glass: (i)

The existence of phase separation has been observed from the DTA study which confirms the formation of nano-composites with the addition of GNPs. Also, the prepared glasses are thermally stable and are highly suitable for the fabrication of optical fibers.

(ii)

The results of FESEM evidenced the formation of bigger size particles due to the coagulation of GNPs.

(iii)

Ellipsometry studies show that the refractive index of glasses is very high that further increases with the increase in the size of the GNPs because of the formation of non-bridging oxygens that are highly polarizable in nature. This high refractive index makes these glasses highly suitable for the application in sensors based on long-range surface plasmon resonance.

(iv)

The nonlinear absorption coefficient and the nonlinear refractive index have been calculated using the Z-scan technique. The nonlinear absorption coefficient decreases with the increase in particle size due to the suppression of electronic transition. Whereas, the nonlinear refractive index increases that make such glasses highly suitable for application in optical devices.

12

Acknowledgments: Authors thank the Department of Science and Technology (DST) for the funding (SR\LOP-019\2013). Authors acknowledge support from Gajendra Mulay for Z-scan, N. Kulkarni for the XRD and Mr. Rudheer Bapat for the FESEM images.

13

References: [1]

V.A. Markel, V.M. Shalaev, E.B. Stechel, W. Kim, R.L. Armstrong, Small-particle composites .1. Linear optical properties, Phys. Rev. B. 53 (1996) 2425–2436.

[2]

V.M. Shalaev, Electromagnetic properties of small-particle composites, Phys. Rep. 272 (1996) 61–137.

[3]

Y. Wu, X. Shen, S. Dai, Y. Xu, F. Chen, C. Lin, T. Xu, Silver Nanoparticles Enhanced Upconversion Luminescence in Er3+/Yb3+ Codoped Bismuth-Germanate Glasses, J. Phys. Chem. C. 115 (2011) 25040–25045.

[4]

M.I. Stockman, V.M. Shalaev, M. Moskovits, R. Botet, T.F. George, Enhanced Raman Scattering by Fractal Clusters: Scale Invariant Theory, Phys. Rev. B. 46 (1992) 2821– 2830.

[5]

M. Moskovits, Surface-enhanced spectroscopy, Rev. Mod. Phys. 57 (1985) 783–826.

[6]

R. Rajaramakrishna, S. Karuthedath, R. V Anavekar, H. Jain, Nonlinear optical studies of lead lanthanum borate glass doped with Au nanoparticles, J. Non. Cryst. Solids. 358 (2012) 1667–1672.

[7]

S. V. Karpov, V.S. Gerasimov, I.L. Isaev, V.A. Markel, Local anisotropy and giant enhancement of local electromagnetic fields in fractal aggregates of metal nanoparticles, Phys. Rev. B - Condens. Matter Mater. Phys. 72 (2005) 205425– 205433.

[8]

Y.P. Sun, J.E. Riggs, H.W. Rollins, R. Guduru, Strong optical limiting of silvercontaining nanocrystalline particles in stable suspensions, J. Phys. Chem. B. 103 (1999) 77–82.

[9]

J. Staromlynska, T.J. McKay, P. Wilson, Broadband optical limiting based on excited state absorption in Pt:ethynyl, J. Appl. Phys. 88 (2000) 1726.

[10] K. Wundke, S. Pötting, J. Auxier, A. Schülzgen, N. Peyghambarian, N.F. Borrelli, PbS 14

quantum-dot-doped glasses for ultrashort-pulse generation, Appl. Phys. Lett. 76 (2000) 5–8. [11] F. Chen, S. Dai, T. Xu, X. Shen, C. Lin, Q. Nie, C. Liu, J. Heo, Surface-plasmon enhanced ultrafast third-order optical nonlinearities in ellipsoidal gold nanoparticles embedded bismuthate glasses, Chem. Phys. Lett. 514 (2011) 79–82. [12] H. Inouye, K. Tanaka, I. Tanahashi, K. Hirao, Ultrafast dynamics of nonequilibrium electrons in a gold nanoparticle system, Phys. Rev. B. 57 (1998) 11334–11340. [13] S. Link, M.A. El-Sayed, Size and Temperature Dependence of the Plasmon Absorption of Colloidal Gold Nanoparticles, J. Phys. Chem. B. 103 (1999) 4212–4217. [14] J. Sasai, K. Hirao, Relaxation behavior of nonlinear optical response in borate glasses containing gold nanoparticles, J. Appl. Phys. 89 (2001) 4548–4553. [15] F. Hache, D. Ricard, C. Flytzanis, Optical nonlinearities of small metal particles: surface-mediated resonance and quantum size effects, J. Opt. Soc. Am. B. 3 (1986) 1647–1655. [16] A. Polman, D.C. Jacobson, D.J. Eaglesham, R.C. Kistler, J.M. Poate, Optical doping of waveguide materials by MeV Er implantation, J. Appl. Phys. 70 (1991) 3778–3784. [17] H. Zeng, J. Qiu, Z. Ye, C. Zhu, F. Gan, Irradiation assisted fabrication of gold nanoparticles-doped glasses, J. Cryst. Growth. 267 (2004) 156–160. [18] S.K. Ghosh, T. Pal, Interparticle Coupling Effect on the Surface Plasmon Resonance of Gold Nanoparticles : From Theory to Applications, Chem. Rev. 107 (2007) 4797– 4862. [19] A. Awang, S.K. Ghoshal, M.R. Sahar, R. Arifin, F. Nawaz, Non-spherical gold nanoparticles mediated surface plasmon resonance in Er3+ doped zinc-sodium tellurite glasses: Role of heat treatment, J. Lumin. 149 (2014) 138–143. [20] S. Eustis, M.A. El-sayed, M. Kasha, Why gold nanoparticles are more precious than

15

pretty gold : Noble metal surface plasmon resonance and its enhancement of the radiative and nonradiative properties of nanocrystals of different shapes, Chem. Soc. Rev. 35 (2006) 209–217. [21] R. West, Y. Wang, T. Goodson, Nonlinear absorption properties in novel gold nanostructured topologies, J. Phys. Chem. B. 107 (2003) 3419–3426. [22] R.P.A. T. Castro, R. Reifenberger, E. Choi, Size-dependent melting temperature ofindividual nanometer-sized metallic clusters, Phys. Rev. B. 42 (1990) 8548–8557. [23] H. Doweidar, G. El-Damrawi, E.F. El Agammy, Structural correlations in BaO-PbOB2O3 glasses as inferred from FTIR spectra, Vib. Spectrosc. 73 (2014) 90–96. [24] Y.B. Saddeek, M.S. Gaafar, Physical and Structural Properties of Some Bismuth Borate Glasses, Mater. Chem. Phys. 115 (2009) 280–286. [25] I. Oprea, H. Hesse, K. Betzler, Optical properties of bismuth borate glasses, Opt. Mater. (Amst). 26 (2004) 235–237. [26] J. Ashok, M. Kostrzewa, M. Srinivasa Reddy, V. Ravi Kumar, N. Venkatramiah, M. Piasecki, N. Veeraiah, Structural and physical characteristics of Au2O3-doped sodium antimonate glasses-part I, J. Am. Ceram. Soc. 102 (2018) 1628–1641. [27] S. Singla, V. Gopal, N. Mahendru, S.S. Prabhu, M. Falconieri, G. Sharma, High refractive index gold nanoparticle doped Bi2O3-B2O3 glasses for THz frequencies, Opt. Mater. (Amst). 72 (2017) 91–97. [28] M.G. Kuzyk, C.W. Dirk, Characterization Techniques and Tabulations for Organic Nonlinear Materials, Marcel Dekker, (1998) 655–692. [29] A. Le Rouge, H. El Hamzaoui, B. Capoen, R. Bernard, G. Martinelli, C. Cassagne, G. Boudebs, M. Bouazaoui, L. Bigot, Synthesis and nonlinear optical properties of zirconia-protected gold nanoparticles embedded in sol – gel derived silica glass, Mater. Res. Express. 2 (2015) 1–10.

16

[30] G. Senthil Murugan, Dielectric, linear and non-linear optical properties of lithium borate–bismuth tungstate glasses and glass-ceramics, J. Non. Cryst. Solids. 279 (2001) 1–13. [31] H. Zeng, G. Chen, J. Qiu, X. Jiang, C. Zhu, Effect of PbO on precipitation of laserinduced gold nanoparticles inside silicate glasses, J. Non. Cryst. Solids. 354 (2008) 1155–1158. [32] J.F. Gomes, A.M.O. Lima, M. Sandrini, A.N. Medina, A. Steimacher, F. Pedrochi, M.J. Barboza, Optical and spectroscopic study of erbium doped calcium borotellurite glasses, Opt. Mater. (Amst). 66 (2017) 211–219. [33] A. Tarafder, A.R. Molla, C. Dey, B. Karmakar, Thermal, structural, and enhanced photoluminescence properties of Eu3+-doped transparent willemite glass-ceramic nanocomposites, J. Am. Ceram. Soc. 96 (2013) 2424–2431. [34] I. Jlassi, H. Elhouichet, M. Ferid, Thermal and optical properties of tellurite glasses doped erbium, J. Mater. Sci. 46 (2011) 806–812. [35] M. Peng, C. Zollfrank, L. Wondraczek, Origin of broad NIR photoluminescence in bismuthate glass and Bi-doped glasses at Room Temperature, J. Phys. Condens. Matter. 21 (2009) 285106. [36] S.K. Ghoshal, A. Awang, M.R. Sahar, R. Ari, Gold nanoparticles assisted surface enhanced Raman scattering and luminescence of Er3+ doped zinc – sodium tellurite glass, J. Lumin. 159 (2015) 265–273. [37] L. Wang, X. Liu, J. Hao, L. Chu, Sensors and Actuators B : Chemical Long-range surface plasmon resonance sensors fabricated with plasma polymerized fluorocarbon thin films, Sensors Actuators B. Chem. 215 (2015) 368–372. [38] M. Sheik-Bahae, A.A. Said, T.H. Wei, D.J. Hagan, E.W. Van Stryland, Sensitive Measurement of Optical Nonlinearities Using a Single Beam, IEEE J. Quantum

17

Electron. 26 (1990) 760–769. [39] T. Xu, F. Chen, X. Shen, S. Dai, Q. Nie, X. Wang, Observation of surface plasmon resonance of silver particles and enhanced third-order optical nonlinearities in AgCl doped Bi2O3-B2O3-SiO2 ternary glasses, Mater. Res. Bull. 45 (2010) 1501–1505. [40] A.A. Scalisi, G. Compagnini, L. D’Urso, O. Puglisi, Nonlinear optical activity in AgSiO2 nanocomposite thin films with different silver concentration, Appl. Surf. Sci. 226 (2004) 237–241. [41] Y. Huang, W. Xiang, S. Lin, R. Cao, Y. Zhang, J. Zhong, X. Liang, The synthesis of bimetallic gold plus nickel nanoparticles dispersed in a glass host and behaviorenhanced optical nonlinearities, J. Non. Cryst. Solids. 459 (2017) 142–149. [42] H. Gao, W. Xiang, X. Ma, L. Ma, Y. Huang, H. Ni, X. Shi, G. Chen, X. Liang, Sol-gel synthesis and third-order optical nonlinearity of Au nanoparticles doped monolithic glass, Gold Bull. 48 (2015) 153–159. [43] W. Xiang, H. Gao, L. Ma, X. Ma, Y. Huang, L. Pei, X. Liang, Valence State Control and Third-Order Nonlinear Optical Properties of Copper Embedded in Sodium Borosilicate Glass, ACS Appl. Mater. Interfaces. 7 (2015) 10162–10168. [44] J.M.P. Almeida, D.S. Da Silva, L.R.P. Kassab, S.C. Zilio, C.R. Mendonça, L. De Boni, Ultrafast third-order optical nonlinearities of heavy metal oxide glasses containing gold nanoparticles, Opt. Mater. (Amst). 36 (2014) 829–832. [45] G. Jagannath, B. Eraiah, K. NagaKrishnakanth, S. Venugopal Rao, Linear and nonlinear optical properties of gold nanoparticles doped borate glasses, J. Non. Cryst. Solids. 482 (2018) 160–169. [46] E. Cattaruzza, G. Battaglin, P. Calvelli, F. Gonella, G. Mattei, C. Maurizio, P. Mazzoldi, S. Padovani, R. Polloni, C. Sada, B.F. Scremin, F. D’Acapito, Fast nonlinear refractive index of pure and alloy metallic nanoclusters in silica glass,

18

Compos. Sci. Technol. 63 (2003) 1203–1208.

19

Figure Captions Figure 1. Picture of sample (a) BiB0, (b) BiB10, (c) BiB40 and (d) BiB100. Figure 2. X-ray diffraction spectra of the prepared systems. Figure 3. FESEM image of (a) BiB, (b) BiB10, (c) BiB40 and BiB100. Circles have been used here to highlight the nanoparticles. Figure 4. Thermograph of the prepared glass samples. Figure 5. Transmission spectra of 35Bi2O3:65B2O3 undoped and doped with differently sized 3 x 108 number of GNPs. Figure 6. The dispersion plots of different glasses obtained from ellipsometry are shown. Figure 7. Z-scan curves obtained from (a) Open aperture and (b) Closed aperture setup taken at 800 nm. The solid square dots are the experimental data and solid lines represent the theoretical fits.

20

Table titles Table 1. Composition of the prepared glass samples. Table 2. Thermal and optical parameters of the prepared glass systems. Table 3. Cauchy model parameter obtained from ellipsometry. Table 4. The nonlinear absorption coefficient of the prepared system:

21

Figures

Figure 1. Picture of sample (a) BiB0, (b) BiB10, (c) BiB40 and (d) BiB100.

22

Intensity (a.u.)

BiB BiB10 BiB40 BiB100

20

30

40

50

60

2θ (degree)

Figure 2. X-ray diffraction spectra of the prepared systems.

23

70

80

Figure 3. FESEM image of (a) BiB, (b) BiB10, (c) BiB40 and BiB100. Circles have been used here to highlight the nanoparticles.

24

EXO

BiB100

Tp1

Tg

Tp2

T

x

Tm BiB40 Tg

Tp1

Tp2

T

∆T

x

BiB10

Tm

Tp1 Tp2

Tg

T

x

Tp

Tg

ENDO

BiB

Tm

Tx Tm 100 200 300 400 500 600 700 800 o

Tempertaure ( C) Figure 4. Thermograph of the prepared glass samples.

25

100 BiB BiB10 BiB40 BiB100

Tramsnission (%)

80

60

40

20

0 200

300

400

500

600

700

800

900

Wavelength (nm)

Figure 5. Transmission spectra of 35Bi2O3:65B2O3 undoped and doped with differently sized 3 x 108 number of GNPs.

26

Refractive index

3.5

BiB BiB10 BiB40 BiB100

3.0

2.5

2.0

400

600

800

1000

1200

1400

1600

Wavelength (nm)

Figure 6. The dispersion plots of different glasses obtained from ellipsometry are shown.

27

Normalized transmittance (a.u.)

1.0 0.9 0.8 0.7 0.6 0.5

BiB BiB10 BiB40 BiB100 (a)

-20

0

20

Z (mm) Normalized Transmittance (a.u.)

2.0

1.6

1.2

0.8

0.4

BiB BiB10 BiB40 BiB100 (b)

0.0 -40

-20

0

20

40

Z (mm)

Figure 7. Z-scan curves obtained from (a) Open aperture and (b) Closed aperture setup taken

at 800 nm. The solid square dots are the experimental data and solid lines represent the theoretical fits.

28

Tables Table 1. Composition of the prepared glass samples.

S.No. Sample name

Composition (mol%) Bi2O3

B2O3

Number of GNPs

Size of the GNPs (nm)

1.

BiB

35

65

-

-

2.

BiB10

35

65

3 x 108

10

3.

BiB40

35

65

3 x 108

40

4.

BiB100

35

65

3 x 108

100

Table 2. Thermal and optical parameters of the prepared glass systems.

Sample Name

Tg (oC)

Tx (oC)

Tp (oC) Tp1

Tp2

Tm (oC)

∆T=Tx-Tg

BiB

444

571

592

-

722

128

BiB10

443

554

571

615

722

111

BiB40

439

555

580

609

722

116

BiB100

435

562

582

617

722

121

Table 3. Cauchy model parameter obtained from ellipsometery.

Sample

a

b

C

kAmp

Exponent

MSE

BiB

1.700±0.008

-0.003

0.00

0±0.001

1.5

38.081

BiB10

1.717±0.002

-0.01

0.00

0±0.000

10

10.573

BiB40

2.006±0.022

-0.003

0.00

0±0.001

1.5

34.173

BiB100

2.312±0.023

0.001

0.00

0±0.000

5.4

55.636

29

Table 4. Nonlinear absorption coefficient of the prepared system: Sample name

β (m/W)

n2 (m2/W)

T

BiB

5.17 × 10-12

1.05 x 10-18

3.94

BiB10

3.8 × 10-12

2.02 x 10-18

1.52

BiB40

1.43 × 10-13

2.20 x 10-18

0.02

BiB100

9.04 × 10-13

2.51 x 10-18

0.05

30

Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: