Photoluminescence study of barium borophosphate glasses doped with Sm3+ ions

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ScienceDirect Materials Today: Proceedings 5 (2018) 15049–15053

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ICAPMA_2017

Photoluminescence study of barium borophosphate glasses doped with Sm3+ ions N. Chanthimaa,b, J. Kaewkhaoa,b, C.K. Jayasankarc, W. Lertlopd,* a

Physics Program, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, Nakhon Pathom, 73000, Thailand b Center of Excellence in Glass Technology and Materials Science (CEGM), Nakhon Pathom Rajabhat University, Nakhon Pathom, 73000, Thailand c Department of Physics, Sri Venkateswara University, Tirupati 517 502, India d Applied Physics, Faculty of Science and Technology, Suan Sunandha Rajabhat University, Bangkok 10300, Thailand

Abstract Barium borophosphate (BaO-B2O3-P2O5) glasses doped with Sm3+ ions were produced by melt quenching procedure. The doping concentration of the Sm3+ was varied from 0.2 mol% to 1.0 mol%. The obtained glasses were characterized through optical absorption and photoluminescence (PL) spectral measurements. The emission spectra corresponding to the Sm3+: 4G5/2  6H5/2 (562 nm), 4G5/2  6H7/2 (597 nm), 4G5/2  6H9/2 (643 nm) and 4G5/2  6H11/2 (704 nm) transitions were obtained under excited wavelength at 401 nm. The photoluminescence intensities of all glasses are comparable and the strongest intensity peak at 597 nm was obtained with 0.4 mol% Sm3+ ions. In order to identify the emission color of the prepared glasses, the emission intensities were analyzed using the 1931 CIE chromatic color coordinates. © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of 3rd International Conference on Applied Physics and Materials Applications. Keywords: Luminescence properties; Phosphate glass; Physical properties; Samarium

1. Introduction Normally, phosphate glasses have linked PO4 structural units with covalent bonding oxygen’s that affect to the some unique physical properties, which better than borate and silicate glasses [1]. This glass has been of large interest for a variety of technological applications due to unique properties such as high thermal expansion

* Corresponding author. Tel.: +66 81 921 8716; fax: +66 2160 1143. E-mail address: [email protected], [email protected] 2214-7853 © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of 3rd International Conference on Applied Physics and Materials Applications.

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coefficient, low viscosity, low chemical durability, UV transmission or electrical conduction [2-4]. However, the pure phosphate network is not stable because of it’s hydroscopic nature. The addition of B2O3 to a phosphate network improves the chemical durability as well as the thermal and mechanical stability of pure phosphate glass [5]. The agglomeration of B2O3 into metaphosphate glasses produces new linkages between phosphate chains through P–O–B bonds [6]. There have been some studies on borophosphate glasses with various network modifiers that have been developed for widespread applications, including hermetic sealing materials [7-9], fast ion conductors and solid state batteries [10]. Glasses based on BaO show interesting physical properties such as good chemical durability and higher refractive indices. Trivalent rare earth (RE3+) ions play vital role in modern optical technology and display fields due to the abundant emission color based on their 4f-4f or 5d-4f transitions [7]. Glasses doped with RE3+ ions are important materials for bulk laser, waveguide laser and opticalfibers because they emit intense radiation in visible, NIR and IR regions under appropriate excitation condition [2]. Trivalent samarium (Sm3+) is the most interesting ions because of its potential applications in various optical devices such as high density optical storage, under sea-communication and color displays and visible solid-state lasers due to its bright emission in orange/red regions. Its emit 4G5/2 level exhibits relatively high quantum efficiency [11]. In the present work, barium borophosphate (BaO-B2O3-P2O5) glasses doped with Sm3+ ions were prepared by the melting and quenching process. The optical absorption and photoluminescence properties of the obtained glasses were studied using a spectrophotometer at room temperature. The the 1931 CIE chromatic color coordinates was also investigated using emission data to confirm orange/red emission from glasses. 2. Experimental details 2.1 Glass preparation Barium borophosphate glass doped with Sm3+ ions in composition 25BaO : 5B2O3 : (70-x)P2O5 : xSm2O3 (BaBPSm), where x is 0.2, 0.4, 0.6, 0.8 and 1.0 mol%, were prepared by the conventional melt quenching technique. A batch of 20 g was weighed, appropriate amounts of reagent grade chemicals barium carbonate (BaCO3), boric acid (B2CO3), ammonium dihydrogen orthophosphate (NH4H2PO4) and samarium oxide (Sm2O3) powders, thoroughly mixed and then placed into a porcelain crucible and melted at 1200 °C for 3 hour in a muffle furnace. After retaining the melt at that temperature, it was cast into stainless steel mould at room temperature. The obtained glass samples were then annealed at 500 °C for 3 hour to relieve any residual stress developed during glass quenching and then slowly cooled to room temperature. Glass samples were cut and finely polished in order to study their properties. The photograph of the glass samples are shown in Fig. 1. 2.2 Measurements The optical absorption spectra were measured by UV-Vis-NIR spectrophotometer (Shimadzu, UV-3600) in the ultraviolet visible and near-infrared (UV-Vis-NIR) region from 200 to 2500 nm. The emission spectra and lifetime were studied by using a fluorescence spectrophotometer (Agilent Technologies, Cary Eclipse) with xenon lamp as a light source. All these measurements were recorded at room temperature.

0.2 mol%

0.4 mol%

0.6 mol%

0.8 mol%

Fig. 1. Photograph of the glass samples with different Sm2O3 concentration.

1.0 mol%

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3. Results and discussion The optical absorption spectra of the glass samples in the UV–Vis and NIR regions (200–2500 nm) are shown in Fig. 2. The observed nine bands (Fig. 2b) of BaBPSm glasses at 401 nm, 473 nm, 948 nm, 1081 nm, 1233 nm, 1380 nm, 1485 nm, 1537 nm and 1585 nm corresponding to the absorption transitions of the Sm3+ ions are given in Table 1. The 6H5/2  6F7/2 transition possesses higher intensity compare to the other transitions and follows the selection rules, |∆S| = 0, |∆L| ≤ 2 and |∆J| ≤ 2. This transition is known as hypersensitive transition. Table 1. Absorption transitions of BaBPSm glass samples. Wavelength,  (nm) 401 473 948 1081 1233

No. 1 2 3 4 5

Absorption Transitions 6 H5/2  4K11/2 6 H5/2  4F5/2 + 4I13/2 6 H5/2  6F11/2 6 H5/2  6F9/2 6 H5/2  6F7/2

No. 6 7 8 9

Wavelength,  (nm) 1380 1485 1537 1585

Absorption Transitions H5/2  6F5/2 6 H5/2  6F3/2 6 H5/2  6H5/2 6 H5/2  6F3/2 6

Sm2O3

1.0 mol%

0.8 mol%

0.6 mol% 0.4 mol% 0.2 mol% 250

500

750 1000 1250 1500 1750 2000 2250 2500

Wavelength (nm)

Sm2O3 1.0 mol%

Normalized absorbance (arb. units)

Normalized absorbance (arb. units)

(a)

(b) 5 6

1

4

7 8 9

2

350

400

450

3

500

1000

1200

1400

1600

1800

Wavelength (nm)

Fig. 2. The optical absorption spectra of BaBPSm glass samples for (a) all concentrations and (b) 1.00 mol% of Sm2O3 concentration.

The photoluminescence excitation (PLE) and emission (PL) spectra of the Sm3+ doped barium borophosphate glasses have been shown in Fig. 3. The PLE and PL spectra of glass samples were monitoring emissions and excitations at 597 and 401 nm, respectively. In the 300–550 nm wavelength range, ten excitation bands are identified which are assigned to the electronic transitions as shown in Fig. 3(a). Also, four emission bands in the wavelength range 500–750 nm are identified and assigned in Fig. 3(b) [12,13]. In these figure, it reveals that as increasing Sm3+ concentration, the emission intensities increases gradually and reaches the maximum at 0.4 mol%. However, the intensity decreased is clearly observed at the Sm3+ concentration beyond 0.4 mol% due to concentration quenching. In many inorganic materials, an excessive doping of emission ions usually decreases the emission intensity remarkably. The phenomenon is called concentration quenching, which is caused by the migration of excitation energy between the emission ions or energy migration to quenching centers where the excitation energy is lost by non-radiative transition.

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Sm2O3

401 nm

(a)

6

( P3/2)

0.4 mol%

(b)

em= 597 nm

Sm2O3

0.4 mol%

597 nm 6

( H7/2)

0.6 mol%

362 nm

Intensity (arb. units)

Intensity (arb. units)

6

H5/2

4

( D3/2)

345 nm

374 nm

4

( H9/2)

0.8 mol%

6

( P7/2)

333 nm

( G9/2)

( I11/2)

( P5/2)

1.0 mol% 0.2 mol%

438 nm

4

( P3/2) 325

4

6

318 nm

300

473 nm

415 nm

4

375

400

425

450

4

G5/2

0.6 mol% 643 nm 6

0.8 mol%

( H9/2)

562 nm

1.0 mol%

6

( H5/2)

0.2 mol% 704 nm

527 nm

4

( G9/2) 350

ex= 401 nm

6

( H11/2)

4

( F3/2) 475

500

525

550

500

525

550

575

600

625

650

675

700

725

750

Wavelength (nm)

Wavelength (nm)

Fig. 3. Photoluminescence (a) excitation and (b) emission spectra of BaBPSm glass samples.

Fig. 4. CIE (x, y) chromaticity coordinates of BaBPSm glass samples. Table 2. The CIE (x, y) chromaticity coordinates of BaBPSm glass samples under 401 nm excitation. Sm2O3 concentration (mol%) 0.2 0.4 0.6 0.8 1.0

Color coordinates x 0.5901 0.5909 0.5912 0.5912 0.5916

y 0.4091 0.4083 0.4080 0.4080 0.4076

Most lighting specifications refer to color in terms of the 1931 CIE (Commission International de I’Eclairage) chromatic color coordinates, which recognize that the human visual system uses three primary colors: red, green and

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blue [14]. In general, the color of any light source can be represented as (x, y) coordinates in this color space. The CIE (x, y) chromaticity coordinates of BaBPSm glasses was calculated by the relative ration of orange (597 nm) to red (643 nm) emission band for glass samples under 401 nm excitation as shown in Table 2. It can be seen that the chromaticity coordinates lie with in the orange light region for all of conditions with increasing concentration of Sm3+ ions as shown in Fig. 4. This fact reveals that orange/red light can be achieved in Sm3+ doped barium borophosphate glasses; however, the quality of the orange/red light achieved from it may not reach the required standards of visible lasers in the reddish orange spectral region [15-16]. 4. Conclusion Optical and luminescence properties of Sm3+ doped barium borophosphate glasses have been studied. The result shows that, the all appearance of the absorption spectra are absorb photon in visible light and near infrared region. The excitation spectra were recorded by monitoring an intense emission at 597 nm, it was found that ten obvious excitation bands are observed. The emission spectra (excited at 401 nm) were observed four emission bands, which the emission band centered at 562, 597, 643 and 704 nm. These bands have shown a bright fluorescent orange and red emission respectively, apart from 597 nm and 643 nm emission transitions. The highest intensity of emission band was obtained at 0.4 mol% Sm3+ ions. The CIE chromaticity coordinates for BaBPSm glasses are located in orange region. Also, the BaBPSm glasses can emit orange light by changing the concentrations of Sm3+. The obtained results demonstrated that BaBPSm glasses can be useful for the development and good candidate as color display or visible lasers in the reddish orange spectral region. Acknowledgments The author would like to thanks National Research Council of Thailand (NRCT) for financial support. Thanks are also due to Suan Sunandha Rajabhat University (SSRU) and Nakhon Pathom Rajabhat University (NPRU) for supporting this research. References [1] K. Brahmachary, D. Rajesh, S. Babu and Y.C. Ratnakaram, J. Mol. Struct. 1064 (2014) 6-14. [2] Y.M. Moustala and K. El-Egili, J. Non-Cryst. Solids. 240 (1998) 144-153. [3] R.K. Brow, J. Non-Cryst. Solids. 263-264 (2000) 1-28. [4] M.I. Abd El-Ati and A.A. Higazy, J. Mater. Sci. 35 (2000) 6175-6180. [5] J.W. Lim, M.L. Schmitt, R.K. Brow and S.W. Yung, J. Non-Cryst. Solids. 356 (2010) 1379-1384. [6] N. Kiran and A. Suresh Kumar, J. Mol. Struct. 1054-1055 (2013) 6–11. [7] D. Raskar, M.T. Rinke and H. Eckert, J. Phys. Chem. C. 112 (2008) 12530-12539. [8] J. Jirak, L. Koudelka, J. Pospisil, P. Mosner, L. Montagne and L. Delevoye, J. Mater. Sci. 42 (2007) 8592-8598. [9] K. Srinivasulu, I. Omkaram, H. Obeid, A. Suresh Kumar, and J. L. Rao, J. Phys. Chem. A. 116 (2012) 3547-3555. [10] P.F. James and W. Shi, J. Mater. Sci. 28 (1993) 2260-2266. [11] R. Vijaya, V. Venkatramu, P. Babu, C.K. Jayasankar, U.R. Rodríguez-Mendoza, V. Lavín, J. Non-Cryst. Solids. 365 (2013) 85–92. [12] Y.Ch. Li, Y.H. Chang, Y.F. Lin, Y.Sh. Chang, Y.J. Lin, J. Alloys Compd. 439 (2007) 367–375. [13] G. Lakshminarayana, J. Qiu, Physica B Condens Matter. 404 (2009) 1169–1180. [14] B.K. Grandhe, V.R. Bandi, K. Jang, S.S. Kim, D.S. Shin, Y.I. Lee, J.M. Lim and T. Song, J. Alloys Compd. 509 (2011) 7937-7942. [15] Umamaheswari, D., Jamalaiah, B.C., Sasikala, T., ll-Gon Kim and Rama Moorthy, L., J. Non-Cryst. Solids. 358 (2012) 782–787. [16] A.M. Babu, B.C. Jamalaiah, T. Sasikala, S.A. Saleem, L.R. Moorthy, J. Alloys Compd. 509 (2011) 4743–4747.