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Effect of gold nanoparticles on Sm3+ luminescence in tellurite glasses
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 5 (2018) 14194–14198
www.materialstoday.com/proceedings
SACT 2016
Effect of gold nanoparticles on Sm3+ luminescence in tellurite glasses Y. Ruangtaweepa,b,*, P. Yasakaa,c, J. Kaewkhaoa,c a
Center of Excellence in Glass Technology and Materials Science (CEGM), Nakhon Pathom Rajabhat University, Nakhon Pathom 73000, Thailand b Science Program, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, Nakhon Pathom 73000, Thailand c Physics Program, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, Nakhon Pathom 73000, Thailand
Abstract The effects of gold nanoparticles (AuNPs) on luminescence properties of tellurite glasses containing samarium ions (Sm3+) have been investigated. The glass samples with chemical composition of (53.5-x)TeO2 : 10ZnO : 35BaO : 1.5Sm2O3 : xAuNPs (where x= 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05 % by mol) were prepare by the conventional melt quenching technique at 950 oc in ambient atmosphere. The results show that the density and molar volume of glass not depend on AuNPs concentration. The NIR absorption spectra in range 850-2,200 nm are observed eight bands at 948, 1083, 1237, 1385, 1489, 1541, 1592 and 1970 nm. The luminescence spectra of the Sm3+ doped in glasses are observed at 564 (4G5/2 6H5/2), 600 (4G5/2 6H7/2), 646 (4G5/2 6 H9/2) and 707 (4G5/2 6H11/2) nm when excited by a 405 nm source. Moreover, the luminescence intensity of all the emission bands is increased with increasing of AuNPs concentration. © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of SACT 2016. Keywords: Luminescence; Gold nanoparticles; Tellurite glass
1. Introduction Glass doped with various rare-earth ions (RE) have been widely attracted for applications in the fields of solidstate lasers, optical amplifiers, optical detectors, optical fiber cables and the production of wide variety of optical components due to their interesting optical characteristics [1-3]. Among of rare-earth ions, samarium (Sm3+) have received considerable attention recently given their distinctive properties making them especially valuable for color
* Corresponding author. Tel.: +6-699-056-9142; fax: +6-634-261-055. E-mail address: [email protected] 2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of SACT 2016.
Y. Ruangtaweep et al./ Materials Today: Proceedings 5 (2018) 14194–14198
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displays, lasers, temperature sensors and solid-state lighting. The Sm3+ ions in glass matrix lead to red emission with excellent luminescence properties, large stimulated emission cross-section and rich energy levels [4-5]. Tellurite glass is good for hosting rare earth ions due to its high refractive index, low melting temperature and low phonon energy, which minimizes non-radiative loss is lower than the other glasses (silicate, borate and phosphate glasses) [6-7]. In recent years, there has been much interest in enhancement of luminescence properties by introducing noble metal nanoparticles such as gold (AuNPs) and silver (AgNPs) nanoparticles [8-10]. These metal nanoparticles exhibit interesting optical phenomenon related to the increasing of the luminescence intensity and enhancement of the nonlinear optical properties, is called surface plasmon resonance (SPR) [11-12]. SPR is attributed to collective oscillation of the electrons at the surface of nanoparticles which is interacting with the electromagnetic wave [13]. These oscillations can induces a strong electric field at interface of the nanoparticles and its surrounding dielectric, which is mainly attributed to the increased local electric field surrounding RE ions near the metallic nanoparticles as well as the possible energy transfer from metallic nanoparticles to RE ions. As a consequence, enhance the luminescence intensity of neighboring fluorescent RE ions. Therefore, the rates of excitation and emission transitions of the neighboring ions increase drastically [14-17]. 2. Experimental details 2.1. Sample preparation The glass samples doped AuNPs with different concentration were prepared in composition (53.5-x)TeO2 : 10ZnO : 35BaO : 1.5Sm2O3 : xAuNPs (where x= 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05 % by mol) and the compositions are shown in Table 1. All the chemical compositions were finely powder while AuNPs was solution with diameter of 16 nm. The whole of composite were mixed and filled in a high purity alumina crusible (each batch weighs for 20 g). Then the batches were placed in an electrical furnace and then melted at 950oC for 30 minutes. After complete melting, the melt was quenched in air using a preheated stainless steel mould. The quenched glasses were annealed at 350oC for 3 hour to reduce thermal stress, and cooled down to room temperature. Finally, all glass samples were cut and polished for further investigation. Table 1. Chemical compositions of the glass samples. Sample Au0 Au1 Au2 Au3 Au4 Au5
Concentration of AuNPs 0.00 0.01 0.02 0.03 0.04 0.05
TeO2 53.50 53.49 53.48 53.47 53.46 53.45
ZnO 10 10 10 10 10 10
Glass composition (mol%) BaO Sm2O3 35 1.5 35 1.5 35 1.5 35 1.5 35 1.5 35 1.5
AuNPs 0.01 0.02 0.03 0.04 0.05
2.2. Measurements The refractive index (RI) was measured by DR-M2 refractometer. The sodium vapor lamp as the light source (539 nm) was used for measurement and the mono-bromonaphthalene was used as an adhesive coating. The density () was measured by Archimedes' principle using a sensitive microbalance (AND, HR-200). The molar volume (Vm) of glass samples were calculated using the relation, VM= MT/ρ, where MT is the total molecular weight of the multicomponent. The optical absorption spectra were measured by the UV-Vis-NIR Spectrophotometer (UV3600) in wavelength range 300-2,500 nm. For the luminescence properties, emission and excitation spectra of glass samples were measured using Cary Eclipse Fluorescence Spectrophotometer with 351 nm excited radiation from a Xenon compact arc lamps. All measurements were carried at room temperature
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Y. Ruangtaweep et al./ Materials Today: Proceedings 5 (2018) 14194–14198
3. Results and discussion 3.1. Glass sample The tellurite doped AuNPs with different concentration are illustrated in Fig. 1. All of glass sample are obtained the transparent homogenous glass and show the yellow color. While the intensity of color glasses not depend on the increasing of AuNPs content.
Fig. 1. The glass samples with different AuNPs concentration.
3.2. Density, molar volume and refractive index The parameters like density, refractive index and molar volume of present glass samples are shown in Table 2. It has been observed that these parameters not depend on the AuNPs concentration. Actually, when low density component (TeO2) replace by high density component (AuNPs) in glass network, the density and refractive index should be increased. In the present work, the density and refractive index not increased with increasing of AuNPs concentration because the glass ratio is not same with glass formula and also due to the volatilization of low melting point component such as TeO2 when melting at the high temperature [18]. The obtained values of density are within the range of 5.309-5.3250 g/cm3, the measured refractive index are in range of 1.5252-1.5272 and the molar volume values are between 14.0243- 14.1209 cm3/mol. Table 2. The density, refractive index and molar volume values of glass samples. Sample
, (g/cm )
Parameters Vm, (cm3/mol)
RI
Au0 Au1 Au2 Au3 Au4 Au5
5.3144 5.3250 5.3245 5.3096 5.3113 5.3013
28.6808 28.6244 28.6278 28.7089 28.7004 28.7552
1.6547 1.6544 1.6541 1.6541 1.6543 1.6543
3
3.3. Optical absorption spectra The optical absorption spectra of glass samples were analyzed by the UV-VIS-NIR Spectrophotometer at room temperature in the range of 780-2,500 nm, as shown in Fig. 2. The absorption peak reveals eight intense bands at 404, 473, 946, 1084, 1237, 1385, 1490, 1539, 1600 and 1975 nm are assigned to appropriate f-f electronic transitions of Sm3+ ions from 6H5/2 6P3/2, 4I13/2+4I11/2+4I9/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2, 6F1/2 and 6H13/2, respectively [19]. The result shows that the intensity of Sm3+ not depend on the AuNPs concentration.
Y. Ruangtaweep et al./ Materials Today: Proceedings 5 (2018) 14194–14198
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Fig. 2. The absorption spectra of glass samples.
3.4. Excitation and emission spectra The observed excitation and emission spectra of glass samples are shown in Fig. 3(a) and (b), respectively. The excitation spectra were obtained by monitoring in the wavelength region 250–550 nm at emission wavelength 600 nm. The excitation bands are identified at 346, 363, 377, 404, 418, 439, 474 and 528 nm corresponding to the transitions from the ground state 6H5/2 to 4D7/2, 4D3/2, 6P7/2, 6P3/2, 6P3/2, 4G9/2, 4I11/2 and 4F3/2 excited states [20]. The emission spectra of the glass samples were recorded in the wavelength region 500–750 nm using 405 nm excited wavelength. The luminescence spectra exhibit three intense emission bands at 563 (green), 600 (orange), 646 (red) and 707 (red) nm which are attributed to 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions, respectively [20]. The results show that the maximum luminescence enhancement was observed for transitions 4G5/2 to 6H7/2 (600 nm) and the intensity up to 160% when AuNPs 0.02 mol% was added in the glass matrix. This luminescence enhancement of glass samples is due to two possible mechanisms, the energy transfer from AuNPs to Sm3+ ions and the local field enhancement around the Sm3+ ions. [21].
(a) Fig. 3. (a) Excitation spectra; (b) Emission spectra of glass samples.
(b)
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Y. Ruangtaweep et al./ Materials Today: Proceedings 5 (2018) 14194–14198
4. Conclusion In this work, effect of AuNPs on Sm3+ luminescence enhancement in tellurite glass was investigated. The glass samples with AuNPs concentration from 0.0.0 to 0.05 mol% showed yellow color. The density, molar volume and refractive index are not depend on AuNPs concentration because of the glass ratio, which is not same with glass formula, and also due to the evaporation when melting at the high temperature. The absorption spectra of all glass sample reveals eight intense bands at 404, 473, 946, 1084, 1237, 1385, 1490, 1539, 1600 and 1975 nm. The excitation bands are identified at 346, 363, 377, 404, 418, 439, 474 and 528 nm while the emission spectra exhibit three intense emission bands at 563 (green), 600 (orange), 646 (red) and 707 (red) nm. Moreover, the intensity of emission bands of Sm3+ ions was increased when AuNPs was added in the glass matrix. Acknowledgements This work has been supported by the National Research Council of Thailand (NRCT). The thanks are also due to Nakhon Pathom Rajabhat University (NPRU) and Center of Excellence in Glass Technology and Materials Science (CEGM) for the facilities support. References [1] B.C. Jamalaiah , T. Suhasini, L. Rama Moorthy, Il-Gon Kim, Dong-Sun Yoo, Kiwan Jang, Journal of Luminescence. 132 (2012) 1144–1149. [2] G. Venkataiah, C.K. Jayasankar, K. Venkata Krishnaiah, P. Dharmaiah, N. Vijaya, Optical Materials. 40 (2015) 26–35. [3] B. Burtan, Z. Mazurak , J. Cisowski, M. Czaja, R. Lisiecki, Optical Materials. 34 (2012) 2050–2054. [4]. S. Selvi, K. Marimuthu, G. Muralidharan, Journal of Luminescence 159 (2015) 207–218. [5] José A. Jiménez, Journal of Physics and Chemistry of Solids 75 (2014) 1334–1339 [6] A. Awang, S.K. Ghoshal, M.R. Sahar, R. Arifin, Fakhra Nawaz, Journal of Luminescence. 149 (2014) 138–143 [7] G. Lakshminarayana, Jianrong Qiu, Journal of Alloys and Compounds. 478 (2009) 630–635. [8] I. Soltani, S. Hraiech, K. Horchani-Naifer, H. Elhouichet, M. Férid, Optical Materials. 46 (2015) 454–460. [9] M. Reza Dousti, Raja J. Amjad, Zahra Ashur S. Mahraz, Journal of Molecular Structure. 1079 (2015) 347–352. [10] R. de Almeida, D. M. da Silva, L.R.P. Kassab, C.B. de Arau ´jo, Optics Communications. 281 (2008) 108–112. [11] G. Venkateswara Rao, H.D. Shashikala, Journal of Non-Crystalline Solids. 402 (2014) 204–209. [12] M. Reza Dousti, S. Raheleh Hosseinian, Journal of Luminescence. 154 (2014) 218–223. [13] M. Reza Dousti, G.Y. Poirier, R.J. Amjad, A.S.S. de Camargo, Optical Materials. 60 (2016) 331-340. [14] Z.A.S. Mahraz, M.R. Sahar, S.K. Ghoshal, Journal of Alloys and Compounds. 649 (2015) 1102-1109. [15] Libo Wu, Yaxun Zhou, Zizhong Zhou, Pan Cheng, Bo Huang, Optical Materials. 57 (2016) 185-192. [16] N.M. Yusoff, M.R. Sahar, Physica B 456 (2015) 191–196. [17] M. R. Sahar, N.M. Yusoff, Materials Today: Proceedings ( 2015 ) 5117 – 5121. [18] J. E. Shelby, Introduction to Glass Science and Technology, Royal Society of Chemistry, Cambridge, 2005. [19] Phan Van Do, Vu Phi Tuyen, Vu Xuan Quang, Le Xuan Hung, Luong Duy Thanh, Tran Ngoc, Ngo Van Tam and Bui The Huy, Optical Materials 55 (2016) 62–67. [20] N. Wantana, S. Kaewjaeng, S. Kothan, H.J. Kim, J. Kaewkhao, Journal of Luminescence 181 (2017) 382–386. [21] S.Tirtha, K. Basudeb, Solid State Sciences 11 (2009) 1044–1051.
ScienceDirect Materials Today: Proceedings 5 (2018) 14194–14198
www.materialstoday.com/proceedings
SACT 2016
Effect of gold nanoparticles on Sm3+ luminescence in tellurite glasses Y. Ruangtaweepa,b,*, P. Yasakaa,c, J. Kaewkhaoa,c a
Center of Excellence in Glass Technology and Materials Science (CEGM), Nakhon Pathom Rajabhat University, Nakhon Pathom 73000, Thailand b Science Program, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, Nakhon Pathom 73000, Thailand c Physics Program, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, Nakhon Pathom 73000, Thailand
Abstract The effects of gold nanoparticles (AuNPs) on luminescence properties of tellurite glasses containing samarium ions (Sm3+) have been investigated. The glass samples with chemical composition of (53.5-x)TeO2 : 10ZnO : 35BaO : 1.5Sm2O3 : xAuNPs (where x= 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05 % by mol) were prepare by the conventional melt quenching technique at 950 oc in ambient atmosphere. The results show that the density and molar volume of glass not depend on AuNPs concentration. The NIR absorption spectra in range 850-2,200 nm are observed eight bands at 948, 1083, 1237, 1385, 1489, 1541, 1592 and 1970 nm. The luminescence spectra of the Sm3+ doped in glasses are observed at 564 (4G5/2 6H5/2), 600 (4G5/2 6H7/2), 646 (4G5/2 6 H9/2) and 707 (4G5/2 6H11/2) nm when excited by a 405 nm source. Moreover, the luminescence intensity of all the emission bands is increased with increasing of AuNPs concentration. © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of SACT 2016. Keywords: Luminescence; Gold nanoparticles; Tellurite glass
1. Introduction Glass doped with various rare-earth ions (RE) have been widely attracted for applications in the fields of solidstate lasers, optical amplifiers, optical detectors, optical fiber cables and the production of wide variety of optical components due to their interesting optical characteristics [1-3]. Among of rare-earth ions, samarium (Sm3+) have received considerable attention recently given their distinctive properties making them especially valuable for color
* Corresponding author. Tel.: +6-699-056-9142; fax: +6-634-261-055. E-mail address: [email protected] 2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of SACT 2016.
Y. Ruangtaweep et al./ Materials Today: Proceedings 5 (2018) 14194–14198
14195
displays, lasers, temperature sensors and solid-state lighting. The Sm3+ ions in glass matrix lead to red emission with excellent luminescence properties, large stimulated emission cross-section and rich energy levels [4-5]. Tellurite glass is good for hosting rare earth ions due to its high refractive index, low melting temperature and low phonon energy, which minimizes non-radiative loss is lower than the other glasses (silicate, borate and phosphate glasses) [6-7]. In recent years, there has been much interest in enhancement of luminescence properties by introducing noble metal nanoparticles such as gold (AuNPs) and silver (AgNPs) nanoparticles [8-10]. These metal nanoparticles exhibit interesting optical phenomenon related to the increasing of the luminescence intensity and enhancement of the nonlinear optical properties, is called surface plasmon resonance (SPR) [11-12]. SPR is attributed to collective oscillation of the electrons at the surface of nanoparticles which is interacting with the electromagnetic wave [13]. These oscillations can induces a strong electric field at interface of the nanoparticles and its surrounding dielectric, which is mainly attributed to the increased local electric field surrounding RE ions near the metallic nanoparticles as well as the possible energy transfer from metallic nanoparticles to RE ions. As a consequence, enhance the luminescence intensity of neighboring fluorescent RE ions. Therefore, the rates of excitation and emission transitions of the neighboring ions increase drastically [14-17]. 2. Experimental details 2.1. Sample preparation The glass samples doped AuNPs with different concentration were prepared in composition (53.5-x)TeO2 : 10ZnO : 35BaO : 1.5Sm2O3 : xAuNPs (where x= 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05 % by mol) and the compositions are shown in Table 1. All the chemical compositions were finely powder while AuNPs was solution with diameter of 16 nm. The whole of composite were mixed and filled in a high purity alumina crusible (each batch weighs for 20 g). Then the batches were placed in an electrical furnace and then melted at 950oC for 30 minutes. After complete melting, the melt was quenched in air using a preheated stainless steel mould. The quenched glasses were annealed at 350oC for 3 hour to reduce thermal stress, and cooled down to room temperature. Finally, all glass samples were cut and polished for further investigation. Table 1. Chemical compositions of the glass samples. Sample Au0 Au1 Au2 Au3 Au4 Au5
Concentration of AuNPs 0.00 0.01 0.02 0.03 0.04 0.05
TeO2 53.50 53.49 53.48 53.47 53.46 53.45
ZnO 10 10 10 10 10 10
Glass composition (mol%) BaO Sm2O3 35 1.5 35 1.5 35 1.5 35 1.5 35 1.5 35 1.5
AuNPs 0.01 0.02 0.03 0.04 0.05
2.2. Measurements The refractive index (RI) was measured by DR-M2 refractometer. The sodium vapor lamp as the light source (539 nm) was used for measurement and the mono-bromonaphthalene was used as an adhesive coating. The density () was measured by Archimedes' principle using a sensitive microbalance (AND, HR-200). The molar volume (Vm) of glass samples were calculated using the relation, VM= MT/ρ, where MT is the total molecular weight of the multicomponent. The optical absorption spectra were measured by the UV-Vis-NIR Spectrophotometer (UV3600) in wavelength range 300-2,500 nm. For the luminescence properties, emission and excitation spectra of glass samples were measured using Cary Eclipse Fluorescence Spectrophotometer with 351 nm excited radiation from a Xenon compact arc lamps. All measurements were carried at room temperature
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Y. Ruangtaweep et al./ Materials Today: Proceedings 5 (2018) 14194–14198
3. Results and discussion 3.1. Glass sample The tellurite doped AuNPs with different concentration are illustrated in Fig. 1. All of glass sample are obtained the transparent homogenous glass and show the yellow color. While the intensity of color glasses not depend on the increasing of AuNPs content.
Fig. 1. The glass samples with different AuNPs concentration.
3.2. Density, molar volume and refractive index The parameters like density, refractive index and molar volume of present glass samples are shown in Table 2. It has been observed that these parameters not depend on the AuNPs concentration. Actually, when low density component (TeO2) replace by high density component (AuNPs) in glass network, the density and refractive index should be increased. In the present work, the density and refractive index not increased with increasing of AuNPs concentration because the glass ratio is not same with glass formula and also due to the volatilization of low melting point component such as TeO2 when melting at the high temperature [18]. The obtained values of density are within the range of 5.309-5.3250 g/cm3, the measured refractive index are in range of 1.5252-1.5272 and the molar volume values are between 14.0243- 14.1209 cm3/mol. Table 2. The density, refractive index and molar volume values of glass samples. Sample
, (g/cm )
Parameters Vm, (cm3/mol)
RI
Au0 Au1 Au2 Au3 Au4 Au5
5.3144 5.3250 5.3245 5.3096 5.3113 5.3013
28.6808 28.6244 28.6278 28.7089 28.7004 28.7552
1.6547 1.6544 1.6541 1.6541 1.6543 1.6543
3
3.3. Optical absorption spectra The optical absorption spectra of glass samples were analyzed by the UV-VIS-NIR Spectrophotometer at room temperature in the range of 780-2,500 nm, as shown in Fig. 2. The absorption peak reveals eight intense bands at 404, 473, 946, 1084, 1237, 1385, 1490, 1539, 1600 and 1975 nm are assigned to appropriate f-f electronic transitions of Sm3+ ions from 6H5/2 6P3/2, 4I13/2+4I11/2+4I9/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2, 6F1/2 and 6H13/2, respectively [19]. The result shows that the intensity of Sm3+ not depend on the AuNPs concentration.
Y. Ruangtaweep et al./ Materials Today: Proceedings 5 (2018) 14194–14198
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Fig. 2. The absorption spectra of glass samples.
3.4. Excitation and emission spectra The observed excitation and emission spectra of glass samples are shown in Fig. 3(a) and (b), respectively. The excitation spectra were obtained by monitoring in the wavelength region 250–550 nm at emission wavelength 600 nm. The excitation bands are identified at 346, 363, 377, 404, 418, 439, 474 and 528 nm corresponding to the transitions from the ground state 6H5/2 to 4D7/2, 4D3/2, 6P7/2, 6P3/2, 6P3/2, 4G9/2, 4I11/2 and 4F3/2 excited states [20]. The emission spectra of the glass samples were recorded in the wavelength region 500–750 nm using 405 nm excited wavelength. The luminescence spectra exhibit three intense emission bands at 563 (green), 600 (orange), 646 (red) and 707 (red) nm which are attributed to 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions, respectively [20]. The results show that the maximum luminescence enhancement was observed for transitions 4G5/2 to 6H7/2 (600 nm) and the intensity up to 160% when AuNPs 0.02 mol% was added in the glass matrix. This luminescence enhancement of glass samples is due to two possible mechanisms, the energy transfer from AuNPs to Sm3+ ions and the local field enhancement around the Sm3+ ions. [21].
(a) Fig. 3. (a) Excitation spectra; (b) Emission spectra of glass samples.
(b)
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4. Conclusion In this work, effect of AuNPs on Sm3+ luminescence enhancement in tellurite glass was investigated. The glass samples with AuNPs concentration from 0.0.0 to 0.05 mol% showed yellow color. The density, molar volume and refractive index are not depend on AuNPs concentration because of the glass ratio, which is not same with glass formula, and also due to the evaporation when melting at the high temperature. The absorption spectra of all glass sample reveals eight intense bands at 404, 473, 946, 1084, 1237, 1385, 1490, 1539, 1600 and 1975 nm. The excitation bands are identified at 346, 363, 377, 404, 418, 439, 474 and 528 nm while the emission spectra exhibit three intense emission bands at 563 (green), 600 (orange), 646 (red) and 707 (red) nm. Moreover, the intensity of emission bands of Sm3+ ions was increased when AuNPs was added in the glass matrix. Acknowledgements This work has been supported by the National Research Council of Thailand (NRCT). The thanks are also due to Nakhon Pathom Rajabhat University (NPRU) and Center of Excellence in Glass Technology and Materials Science (CEGM) for the facilities support. References [1] B.C. Jamalaiah , T. Suhasini, L. Rama Moorthy, Il-Gon Kim, Dong-Sun Yoo, Kiwan Jang, Journal of Luminescence. 132 (2012) 1144–1149. [2] G. Venkataiah, C.K. Jayasankar, K. Venkata Krishnaiah, P. Dharmaiah, N. Vijaya, Optical Materials. 40 (2015) 26–35. [3] B. Burtan, Z. Mazurak , J. Cisowski, M. Czaja, R. Lisiecki, Optical Materials. 34 (2012) 2050–2054. [4]. S. Selvi, K. Marimuthu, G. Muralidharan, Journal of Luminescence 159 (2015) 207–218. [5] José A. Jiménez, Journal of Physics and Chemistry of Solids 75 (2014) 1334–1339 [6] A. Awang, S.K. Ghoshal, M.R. Sahar, R. Arifin, Fakhra Nawaz, Journal of Luminescence. 149 (2014) 138–143 [7] G. Lakshminarayana, Jianrong Qiu, Journal of Alloys and Compounds. 478 (2009) 630–635. [8] I. Soltani, S. Hraiech, K. Horchani-Naifer, H. Elhouichet, M. Férid, Optical Materials. 46 (2015) 454–460. [9] M. Reza Dousti, Raja J. Amjad, Zahra Ashur S. Mahraz, Journal of Molecular Structure. 1079 (2015) 347–352. [10] R. de Almeida, D. M. da Silva, L.R.P. Kassab, C.B. de Arau ´jo, Optics Communications. 281 (2008) 108–112. [11] G. Venkateswara Rao, H.D. Shashikala, Journal of Non-Crystalline Solids. 402 (2014) 204–209. [12] M. Reza Dousti, S. Raheleh Hosseinian, Journal of Luminescence. 154 (2014) 218–223. [13] M. Reza Dousti, G.Y. Poirier, R.J. Amjad, A.S.S. de Camargo, Optical Materials. 60 (2016) 331-340. [14] Z.A.S. Mahraz, M.R. Sahar, S.K. Ghoshal, Journal of Alloys and Compounds. 649 (2015) 1102-1109. [15] Libo Wu, Yaxun Zhou, Zizhong Zhou, Pan Cheng, Bo Huang, Optical Materials. 57 (2016) 185-192. [16] N.M. Yusoff, M.R. Sahar, Physica B 456 (2015) 191–196. [17] M. R. Sahar, N.M. Yusoff, Materials Today: Proceedings ( 2015 ) 5117 – 5121. [18] J. E. Shelby, Introduction to Glass Science and Technology, Royal Society of Chemistry, Cambridge, 2005. [19] Phan Van Do, Vu Phi Tuyen, Vu Xuan Quang, Le Xuan Hung, Luong Duy Thanh, Tran Ngoc, Ngo Van Tam and Bui The Huy, Optical Materials 55 (2016) 62–67. [20] N. Wantana, S. Kaewjaeng, S. Kothan, H.J. Kim, J. Kaewkhao, Journal of Luminescence 181 (2017) 382–386. [21] S.Tirtha, K. Basudeb, Solid State Sciences 11 (2009) 1044–1051.