- Email: [email protected]
WITHDRAWN: Synthesis and energy transfer from Dy3+ to Sm3+ in halosulphate phosphor for solid state lighting applications
Accepted Manuscript
Synthesis and Energy Transfer from Dy3+ to Sm3+ in Halosulphate Phosphor for Solid State Lighting Applications S.T. Taide , K.A. Koparkar , N.B. Ingle , S.K. Omanwar PII: DOI: Reference:
S2405-7223(15)30065-7 10.1016/j.spjpm.2017.08.002 SPJPM 144
To appear in:
St. Petersburg Polytechnical University Journal: Physics and Mathematics
Received date: Revised date: Accepted date:
21 December 2015 12 May 2017 15 August 2017
Please cite this article as: S.T. Taide , K.A. Koparkar , N.B. Ingle , S.K. Omanwar , Synthesis and Energy Transfer from Dy3+ to Sm3+ in Halosulphate Phosphor for Solid State Lighting Applications, St. Petersburg Polytechnical University Journal: Physics and Mathematics (2017), doi: 10.1016/j.spjpm.2017.08.002
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. 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.
ACCEPTED MANUSCRIPT
Synthesis and Energy Transfer from Dy3+ to Sm3+ in Halosulphate Phosphor for Solid State Lighting Applications. S.T.Taide1, K. A. Koparkar1, N.B.Ingle2, S.K.Omanwar3 Department of Physics J.D. Institute of Engg. & Tech. Yavatmal. 2 3
Department of Physics PRMIET, College, Badnera.
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1
Department of Physics, SGB Amravati University, Amravati. (Corresponding Author- [email protected])
Abstract
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A series of Rare Earth (RE) doped ions (Dy3+, Sm3+) in mixed metal halosulphate NaMgSO4F were prepared by simple route of re-crystallization method to produce polycrystalline powder samples. The crystal structures of doped and undoped material were
M
examined by powder X-ray diffraction (XRD) tools, while particle morphology was studied by FE-SEM. The photoluminescence absorption and emission analysis and life time measurement
ED
were carried out to find efficient energy transfer within co-doped phosphors for better luminescence. The multicolor emission from co-doped materials at characteristic excitation
PT
wavelengths suggests a well defined approach towards energy transfer emission for white light
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emission (W-LEDs).
Keywords: Luminescence; Fluorides; Optical material; X-ray diffraction.
AC
1. Introduction
In the development of cutting edge technology, photoluminescence properties of RE ion
doped inorganic material were attract the attention of researcher for their potential and diversified applications in the fields of lasers, fluorescent lighting, display devices, optical detectors, wave guides and fiber amplifiers[1-5], due to their advantages such as energy-saving, reliability, better performance and environmental-friendly etc. [6,7]. However, several
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constrained were appeared in their practical application, especially due to low luminous efficiency and poor color-rendering index [8, 9]. In the emerging trends of display and lighting technology, there is more need to pay an attention towards multi-doped (more than one kind of RE ion) phosphor for multicolor emission
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producing white light with the possibility for tuning wavelength. In these concern alkaline mixed metals sulphates activated with RE ions are known to be good material for PL and TL materials and established as promising candidates for display and lighting applications.
Dysprosium (Dy3+) ions exhibit characteristic emission bands in the blue and yellow
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regions arising from the (4F9/26H15/2) and (4F9/26H13/2) transitions respectively, the Sm3+ ions are excellent activators to produce intense orange or red emissions due to the (4G5/26H7/2,9/2,11/2) transitions, the emission bands of Dy3+ is overlaps with excitation of Sm3+
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which are useful to acquire natural white-light emission depending on the host lattice [10-17]. In this paper, the details of luminescence properties of RE doped NaMgSO4F phosphor
ED
and effect on host excitation by charge compensation of Nal+ ion have been reported. The generation of white light emission within co-doped Dy3+/Sm3+ in NaMgSO4F phosphors and the
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justification of energy transfer model with possible tuning emission are discussed.
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2. Materials and Characterization tools The phosphor materials reported in paper were prepared by a re-crystallization method. The
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starting material used are MgSO4 (99% pure, obtained from alfaspar) and NaF (AR grade) were taken in stiochimetric ratio and dissolved separately in double distilled de-ionized water, which results in formation of solution of NaMgSO4F. MgSO4+NaF (aqueous) ⇒
NaMgSO4F
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Then water soluble salt of dysprosium and samarium was added to this solution confirming that no un-dissolved constituents were left behind and all the salts were completely dissolved in water and thus reacted.
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The compounds NaMgSO4F (pure) and NaMgSO4F:Dy/Sm, in its powder form was obtained by evaporating on 1000C for 6 hrs. The dried samples were taken cooled at room temperature. The resultant polycrystalline mass was crushed to fine particle in a crucible. The same procedure was adopted for NaMgSO4F: Sm and NaMgSO4F:Dy, Sm. The phosphors
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preparation inorganic reaction can be written as
NaMgSO4F (aqueous) + Dy2O3/Sm2O3⇒
NaMgSO4F:Dy/Sm
The prepared samples then taken for characterization, for the identification and confirmation of
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desired product, the crystal structure and phase formation, the sample were examined by powder
ED
XRD technique. The particle morphology was studied by Hitachi type- II FE-SEM. Photoluminescence excitation and emission spectra and life time measurement of various
PT
samples were recorded by using Hitachi F-7000 fluorescence spectrometer. 3. Results and discussion
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3.1. XRD and SEM analysis
XRD pattern of NaMgSO4F and NaMgSO4F:Dy/Sm materials were shown in Fig. 1. The
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structural data of NaMgSO4F host material very well matched with ICDD file No 00-039-0320. There is very small effect of dopants (Dy/Sm) observed on XRD pattern compared with NaMgSO4F host, this is due to dopant concentration is very less compared to host further ionic radii of Dy, Sm and Mg, Na are very much comparable, thus dopant completely take lattice site
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of host and crystal structure not disturb, there is only few extra diffracted peak with less intensity was observed. Fig. 2 shows SEM morphology of NaMgSO4F:Dy/Sm. The particles are highly
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agglomerated by regular grain size with smoothly spherical nature.
Fig. 1 Compared XRD Pattern of Doped & UndopedNaMgSO4F Fig. 2 FE-SEM Micrograph NaMgSO4F: Dy/ Sm
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3.2. Photoluminescence analysis
The PL excitation of NaMgSO4F:Dy3+ depicted in Fig. 3. Emission peaks recorded at 363 nm excitation wavelength shows two main emission peak at 482 nm (blue region) and 574 nm (yellow region) which are assigned to the electronic transitions of (4F9/26H15/2) and
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(4F9/26H13/2) of Dy3+ ions respectively. The excitation monitored at 574 nm shows only
ED
characteristics peak at and around 363 nm. The host absorption between 200-300 nm in simple and mixed sulphate is prominent but in prepared host charge compensation was done by Na1+ ion
PT
providing efficient 3+ state for RE3+ ions there by reducing impure host absorption and increases dopant excitation.
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NaMgSO4F:xSm3+ (x = 0.001, 0.003, 0.005, 0.01) as a function of Sm3+ ion concentration
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by monitoring with the excitation wavelength at 363 nm are as shown in Fig. 4. Emission bands at 564 nm (green region) and 598 nm (orange region), weak band 647 nm are assigned to the (4G5/26H5/2), (4G5/26H7/2) and (4G5/26H9/2) transitions of Sm3+ ions respectively. when the co-doped sample was excited with Dy3+ emission wavelength at 574 nm, only emission peak intensity corresponding to the (4G5/26H7/2) transition of Sm3+ ions increases at the excitation wavelength 363 nm of Dy3+ due to the possibility of energy transfer from 4F9/2 level of Dy3+ to
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the 4G5/2 level of Sm3+ ions. The 4G5/2 level of Sm3+ ions lies lower than the 4F9/2 levels of Dy3+ ions, the emission band at 598 nm corresponding to the 4G5/26H7/2 transition of Sm3+ ions is almost overlapped with the Dy3+ emission band at 574 nm and so the intensity of these emission bands is not remarkably reduced whereas the intensity of blue emission band decreases which
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observed in Fig. 5. The various excitations gives different nature of emission peaks in NaMgSO4F:Dy3+, Sm3+. Therefore, from the above results, we supposed that the energy transfer occurred from blue emission band of Dy3+ ions to Sm3+ ions. The possible ways of energy transfer from Dy3+ ions to Sm3+ ions are shown in Fig. 6.
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Fig. 7 depicted decay curves of phosphors. The decay life time of NaMgSO4F:Dy/Sm, for different dopant concentrations was measured as 2.7 ms, 0.38 ms and 0.57 ms respectively. It is observed that the co-doped phosphor (Dy, Sm) is efficiently excited by the 363 nm (near blue)
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and emission obtained in blue to red region therefore there is possibility to select (tuned) the wavelength for phosphor converted WLEDs. The CIE chromatic coordinate of optimized
ED
composition was found to be (0.38, 0.37), (0.39, 0.40) and (0.40, 0.38) in warm white region are
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close to that of white light (033, 0.33) [18] is as shown in Fig. 8.
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Fig. 3 PL Excitation spectra monitored at em 574 nm and Emission spectra monitored at ex 363 nm of NaMgSO4F:Dy
Fig. 4 PL Excitation spectra monitored at em 598 nm and Emission spectra monitored at ex 363 nm of NaMgSO4F:Sm
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Fig. 5 PL Excitation (em = 598 nm) and Emission spectra of (ex = 363 nm) of NaMgSO4F:Dy, Sm phosphor with variation in Sm concentration
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Fig. 6 Energy transfer scheme Dy (4F9/2) Sm (4G5/2) in NaMgSO4F: Dy, Sm Phosphor
Fig. 7 Decay curves of NaMgSO4F:Dy3+, NaMgSO4F:Sm3+, NaMgSO4F:Dy3+, Sm3+
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Fig. 8 CIE Co-ordinates [a, b, c] of NaMgSO4F:Dy3+, Sm3+
Conclusion
To obtain a better luminescence performance by pure dopant excited luminescence in
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halosulphate was investigated using superior charge compensator Na1+ ion. In mixed metal halosulphate, activated with rare earth (Dy3+/Sm3+) ions, The series of Dy3+ single ions doped
ED
NaMgSO4F were effectively excited by 363 nm radiation and obtained blue and yellow emission while, Dy3+/Sm3+ doped phosphor can effectively excited by 363 nm radiation and get
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Sm3+emission suppressing Dy3+ emission due to energy transfer and exhibit fairly white light
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emission for WLEDs.
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References [1]
B.J. Chen, E.Y.B. Pun, H. Lin, Photoluminescence and spectral parameters of Eu3+ in sodium–aluminum–tellurite ceramics, J. Alloys& Cmpds 479 (2009) 352-356.
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[2]
J. Ingle, A. Gawande, R. Sonekar, S.Omanwar, Y.Wang, L.Zhao Combustion synthesis and optical properties of Oxy-borate phosphorsYCa4O(BO3)3:RE3+(RE = Eu3+,Tb3+) under UV, VUV excitation, J. Alloys &compds585 (2014) 633-635.
[3]
J.Ingle, A.Gawande, R. Sonekar, S.Omanwar, Y.Wang, L.Zhao, Combustion synthesis and
and lighting, J. Alloy & Cmpds 608 (2014) 235-240. [4]
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photoluminescence study of novel red phosphor (Y 1− x− y, Gdx) BaB 9O16: Eu3+y for display
J. Ingle, R. Sonekar, S. Omanwar Combustion synthesis and superior photo-luminescence from rare earth doped (Eu, Tb) lanthanum borates phosphors for display Journal of
[5]
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Materials Science: Materials in Electronics 27 (2016) 10735-10741.
M. Babu, B.C. Jamalaiah, J. Suresh Kumar, T. Sasikala, L. Rama Moorthy, Spectroscopic and photoluminescence properties of Dy3+-doped lead tungsten tellurite glasses for laser
[6]
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materials, Journal of Alloys and Compounds 509 (2011) 457-462. N.B. Ingle, S.K. Omanwar, P.L. Muthal, S.M. Dhopte, V.K. Kondawar, T.K. Gundurao,
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S.V. Moharil. Synthesis of CaSO4:Dy, CaSO4:Eu3+ and CaSO4:Eu2+ phosphors, Radiation measurements 43 (2008) 1191-1197. K. Korthout, P.F. Smet, D. Poelman, Rare earth doped core-shell particles as phosphor for
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[7]
[8]
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warm-white light-emitting diodes ,Appl. Phys. Lett. 98 (2011) 2619-2625. W.J. Park, Y.H. Song, J.W. Moon, S.M. Kang, D.H. Yoon, Synthesis and luminescent
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properties of Eu2+ doped nitrogen-rich Ca-α-SiAlON phosphor for white light-emitting diodes, Solid State Sci. 12 (2010) 1853-1856.
[9]
K.A. Koparkar, N.S. Bajaj, S.K. Omanwar, Combustion synthesis and characterization of phosphor KSr4 (BO3)3:Dy3+ optical materials, 39 (2015) 74–80.
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[10] X.Wei, J. Fan, X. Zhou, Y. Shen*, X.Hu, G. Zuo Synthesis of mesoporous Sr2MgSi2O7:Eu2+, Dy3+ energy storage carriers using cetyl trimethyl ammonium bromide as a template J. Ceram. Sci. Tech., 07 (2016) 477-482 [11] G. Seeta, R. Raju, J. Park, H. Jung, B. Moon, J. Jeong, J. Kim, Luminescence properties of
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Dy3+ : GdAlO3 nano-powder phosphors, Current Appl. Phys. 9 (2009) 92–95.
[12] S.C. Gedam, S.J. Dhoble, S.V. Moharil, 5d→4f transition in halosulphate phosphors, J. Lumin. 126 (2007) 121-129.
[13] S. Taide, N. Ingle, S. Omanwar, Photoluminescence Study of Rare-Earth Activated
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Anhydrite Salt CaSO4: RE (RE= Eu2+, Eu3+, Ce3+, Tb3+, Dy3+ and Sm3+), Advanced Science Letters 22 (2016) 8-12.
[14] S. Taide, N. Ingle, S. Omanwar, Tb3+Luminescence in NaMgSO4Cl Halosulphate Phosphor
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for UV-LED Fluorescent Tubes, Physical Science International Journal 8 (2015) 1-7. [15] S.C. Gedam,S.J. Dhoble, S.V. Moharil, Dy3+and Mn2+ emission in KMgSO4Cl phosphor, J.
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Lumin ,124, (2007) 120–126
[16] S.C. Gedam, S.J. Dhoble, I.M. Nagpure, S.V. Godbole, M.K. Bhide, S.V. Moharil,
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Luminescence of Cu2+ in halosulphate phosphor J. Matter sci. 43 (2008) 3189-3196.
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[17] A. Pandey, R.G. Sonkawade, P.D. Sahare, J. Phys. D Thermo luminescence and Photoluminescence characteristics of nano-crystalline K2Ca2(SO4)3:Eu.Appl. Phys. 35
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(2002) 2744-2747. [18] www.ledtuning.nl/en/cie.php
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Fig. 1 XRD Pattern of Doped and Undoped NaMgSO4F:Dy/Sm
Fig. 2 FE-SEM Micrograph NaMgSO4F: Dy/Sm
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Fig. 3 PL Excitation spectra monitored at em 574 nm and Emission spectra monitored at ex 363 nm of NaMgSO4F:Dy
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Fig. 4 PL Excitation spectra monitored at em 598 nm and Emission spectra
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monitored at ex 363 nm of NaMgSO4F:Sm
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Fig. 5 PL Excitation (em = 598 nm) and Emission spectra of (ex = 363 nm) of NaMgSO4F:Dy, Sm phosphor with variation in Sm concentration
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Fig. 6 Energy transfer scheme Dy (4F9/2) Sm (4G5/2) in NaMgSO4F: Dy/Sm Phosphor
3+
Fig. 7 Decay curves of Different Conc. of Dopants in NaMgSO4F: Dy (0.05
mol%), Sm3+(0.01,0.001,0.03,0.005 mol %)
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Fig. 8 CIE Co-ordinates [a, b, c] of NaMgSO4F:Dy3+/Sm3+
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Synthesis and Energy Transfer from Dy3+ to Sm3+ in Halosulphate Phosphor for Solid State Lighting Applications S.T. Taide , K.A. Koparkar , N.B. Ingle , S.K. Omanwar PII: DOI: Reference:
S2405-7223(15)30065-7 10.1016/j.spjpm.2017.08.002 SPJPM 144
To appear in:
St. Petersburg Polytechnical University Journal: Physics and Mathematics
Received date: Revised date: Accepted date:
21 December 2015 12 May 2017 15 August 2017
Please cite this article as: S.T. Taide , K.A. Koparkar , N.B. Ingle , S.K. Omanwar , Synthesis and Energy Transfer from Dy3+ to Sm3+ in Halosulphate Phosphor for Solid State Lighting Applications, St. Petersburg Polytechnical University Journal: Physics and Mathematics (2017), doi: 10.1016/j.spjpm.2017.08.002
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. 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.
ACCEPTED MANUSCRIPT
Synthesis and Energy Transfer from Dy3+ to Sm3+ in Halosulphate Phosphor for Solid State Lighting Applications. S.T.Taide1, K. A. Koparkar1, N.B.Ingle2, S.K.Omanwar3 Department of Physics J.D. Institute of Engg. & Tech. Yavatmal. 2 3
Department of Physics PRMIET, College, Badnera.
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1
Department of Physics, SGB Amravati University, Amravati. (Corresponding Author- [email protected])
Abstract
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A series of Rare Earth (RE) doped ions (Dy3+, Sm3+) in mixed metal halosulphate NaMgSO4F were prepared by simple route of re-crystallization method to produce polycrystalline powder samples. The crystal structures of doped and undoped material were
M
examined by powder X-ray diffraction (XRD) tools, while particle morphology was studied by FE-SEM. The photoluminescence absorption and emission analysis and life time measurement
ED
were carried out to find efficient energy transfer within co-doped phosphors for better luminescence. The multicolor emission from co-doped materials at characteristic excitation
PT
wavelengths suggests a well defined approach towards energy transfer emission for white light
CE
emission (W-LEDs).
Keywords: Luminescence; Fluorides; Optical material; X-ray diffraction.
AC
1. Introduction
In the development of cutting edge technology, photoluminescence properties of RE ion
doped inorganic material were attract the attention of researcher for their potential and diversified applications in the fields of lasers, fluorescent lighting, display devices, optical detectors, wave guides and fiber amplifiers[1-5], due to their advantages such as energy-saving, reliability, better performance and environmental-friendly etc. [6,7]. However, several
ACCEPTED MANUSCRIPT
constrained were appeared in their practical application, especially due to low luminous efficiency and poor color-rendering index [8, 9]. In the emerging trends of display and lighting technology, there is more need to pay an attention towards multi-doped (more than one kind of RE ion) phosphor for multicolor emission
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producing white light with the possibility for tuning wavelength. In these concern alkaline mixed metals sulphates activated with RE ions are known to be good material for PL and TL materials and established as promising candidates for display and lighting applications.
Dysprosium (Dy3+) ions exhibit characteristic emission bands in the blue and yellow
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regions arising from the (4F9/26H15/2) and (4F9/26H13/2) transitions respectively, the Sm3+ ions are excellent activators to produce intense orange or red emissions due to the (4G5/26H7/2,9/2,11/2) transitions, the emission bands of Dy3+ is overlaps with excitation of Sm3+
M
which are useful to acquire natural white-light emission depending on the host lattice [10-17]. In this paper, the details of luminescence properties of RE doped NaMgSO4F phosphor
ED
and effect on host excitation by charge compensation of Nal+ ion have been reported. The generation of white light emission within co-doped Dy3+/Sm3+ in NaMgSO4F phosphors and the
PT
justification of energy transfer model with possible tuning emission are discussed.
CE
2. Materials and Characterization tools The phosphor materials reported in paper were prepared by a re-crystallization method. The
AC
starting material used are MgSO4 (99% pure, obtained from alfaspar) and NaF (AR grade) were taken in stiochimetric ratio and dissolved separately in double distilled de-ionized water, which results in formation of solution of NaMgSO4F. MgSO4+NaF (aqueous) ⇒
NaMgSO4F
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Then water soluble salt of dysprosium and samarium was added to this solution confirming that no un-dissolved constituents were left behind and all the salts were completely dissolved in water and thus reacted.
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The compounds NaMgSO4F (pure) and NaMgSO4F:Dy/Sm, in its powder form was obtained by evaporating on 1000C for 6 hrs. The dried samples were taken cooled at room temperature. The resultant polycrystalline mass was crushed to fine particle in a crucible. The same procedure was adopted for NaMgSO4F: Sm and NaMgSO4F:Dy, Sm. The phosphors
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preparation inorganic reaction can be written as
NaMgSO4F (aqueous) + Dy2O3/Sm2O3⇒
NaMgSO4F:Dy/Sm
The prepared samples then taken for characterization, for the identification and confirmation of
M
desired product, the crystal structure and phase formation, the sample were examined by powder
ED
XRD technique. The particle morphology was studied by Hitachi type- II FE-SEM. Photoluminescence excitation and emission spectra and life time measurement of various
PT
samples were recorded by using Hitachi F-7000 fluorescence spectrometer. 3. Results and discussion
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3.1. XRD and SEM analysis
XRD pattern of NaMgSO4F and NaMgSO4F:Dy/Sm materials were shown in Fig. 1. The
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structural data of NaMgSO4F host material very well matched with ICDD file No 00-039-0320. There is very small effect of dopants (Dy/Sm) observed on XRD pattern compared with NaMgSO4F host, this is due to dopant concentration is very less compared to host further ionic radii of Dy, Sm and Mg, Na are very much comparable, thus dopant completely take lattice site
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of host and crystal structure not disturb, there is only few extra diffracted peak with less intensity was observed. Fig. 2 shows SEM morphology of NaMgSO4F:Dy/Sm. The particles are highly
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agglomerated by regular grain size with smoothly spherical nature.
Fig. 1 Compared XRD Pattern of Doped & UndopedNaMgSO4F Fig. 2 FE-SEM Micrograph NaMgSO4F: Dy/ Sm
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3.2. Photoluminescence analysis
The PL excitation of NaMgSO4F:Dy3+ depicted in Fig. 3. Emission peaks recorded at 363 nm excitation wavelength shows two main emission peak at 482 nm (blue region) and 574 nm (yellow region) which are assigned to the electronic transitions of (4F9/26H15/2) and
M
(4F9/26H13/2) of Dy3+ ions respectively. The excitation monitored at 574 nm shows only
ED
characteristics peak at and around 363 nm. The host absorption between 200-300 nm in simple and mixed sulphate is prominent but in prepared host charge compensation was done by Na1+ ion
PT
providing efficient 3+ state for RE3+ ions there by reducing impure host absorption and increases dopant excitation.
CE
NaMgSO4F:xSm3+ (x = 0.001, 0.003, 0.005, 0.01) as a function of Sm3+ ion concentration
AC
by monitoring with the excitation wavelength at 363 nm are as shown in Fig. 4. Emission bands at 564 nm (green region) and 598 nm (orange region), weak band 647 nm are assigned to the (4G5/26H5/2), (4G5/26H7/2) and (4G5/26H9/2) transitions of Sm3+ ions respectively. when the co-doped sample was excited with Dy3+ emission wavelength at 574 nm, only emission peak intensity corresponding to the (4G5/26H7/2) transition of Sm3+ ions increases at the excitation wavelength 363 nm of Dy3+ due to the possibility of energy transfer from 4F9/2 level of Dy3+ to
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the 4G5/2 level of Sm3+ ions. The 4G5/2 level of Sm3+ ions lies lower than the 4F9/2 levels of Dy3+ ions, the emission band at 598 nm corresponding to the 4G5/26H7/2 transition of Sm3+ ions is almost overlapped with the Dy3+ emission band at 574 nm and so the intensity of these emission bands is not remarkably reduced whereas the intensity of blue emission band decreases which
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observed in Fig. 5. The various excitations gives different nature of emission peaks in NaMgSO4F:Dy3+, Sm3+. Therefore, from the above results, we supposed that the energy transfer occurred from blue emission band of Dy3+ ions to Sm3+ ions. The possible ways of energy transfer from Dy3+ ions to Sm3+ ions are shown in Fig. 6.
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Fig. 7 depicted decay curves of phosphors. The decay life time of NaMgSO4F:Dy/Sm, for different dopant concentrations was measured as 2.7 ms, 0.38 ms and 0.57 ms respectively. It is observed that the co-doped phosphor (Dy, Sm) is efficiently excited by the 363 nm (near blue)
M
and emission obtained in blue to red region therefore there is possibility to select (tuned) the wavelength for phosphor converted WLEDs. The CIE chromatic coordinate of optimized
ED
composition was found to be (0.38, 0.37), (0.39, 0.40) and (0.40, 0.38) in warm white region are
PT
close to that of white light (033, 0.33) [18] is as shown in Fig. 8.
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Fig. 3 PL Excitation spectra monitored at em 574 nm and Emission spectra monitored at ex 363 nm of NaMgSO4F:Dy
Fig. 4 PL Excitation spectra monitored at em 598 nm and Emission spectra monitored at ex 363 nm of NaMgSO4F:Sm
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Fig. 5 PL Excitation (em = 598 nm) and Emission spectra of (ex = 363 nm) of NaMgSO4F:Dy, Sm phosphor with variation in Sm concentration
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Fig. 6 Energy transfer scheme Dy (4F9/2) Sm (4G5/2) in NaMgSO4F: Dy, Sm Phosphor
Fig. 7 Decay curves of NaMgSO4F:Dy3+, NaMgSO4F:Sm3+, NaMgSO4F:Dy3+, Sm3+
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Fig. 8 CIE Co-ordinates [a, b, c] of NaMgSO4F:Dy3+, Sm3+
Conclusion
To obtain a better luminescence performance by pure dopant excited luminescence in
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halosulphate was investigated using superior charge compensator Na1+ ion. In mixed metal halosulphate, activated with rare earth (Dy3+/Sm3+) ions, The series of Dy3+ single ions doped
ED
NaMgSO4F were effectively excited by 363 nm radiation and obtained blue and yellow emission while, Dy3+/Sm3+ doped phosphor can effectively excited by 363 nm radiation and get
PT
Sm3+emission suppressing Dy3+ emission due to energy transfer and exhibit fairly white light
CE
emission for WLEDs.
AC
References [1]
B.J. Chen, E.Y.B. Pun, H. Lin, Photoluminescence and spectral parameters of Eu3+ in sodium–aluminum–tellurite ceramics, J. Alloys& Cmpds 479 (2009) 352-356.
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[2]
J. Ingle, A. Gawande, R. Sonekar, S.Omanwar, Y.Wang, L.Zhao Combustion synthesis and optical properties of Oxy-borate phosphorsYCa4O(BO3)3:RE3+(RE = Eu3+,Tb3+) under UV, VUV excitation, J. Alloys &compds585 (2014) 633-635.
[3]
J.Ingle, A.Gawande, R. Sonekar, S.Omanwar, Y.Wang, L.Zhao, Combustion synthesis and
and lighting, J. Alloy & Cmpds 608 (2014) 235-240. [4]
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photoluminescence study of novel red phosphor (Y 1− x− y, Gdx) BaB 9O16: Eu3+y for display
J. Ingle, R. Sonekar, S. Omanwar Combustion synthesis and superior photo-luminescence from rare earth doped (Eu, Tb) lanthanum borates phosphors for display Journal of
[5]
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Materials Science: Materials in Electronics 27 (2016) 10735-10741.
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Fig. 1 XRD Pattern of Doped and Undoped NaMgSO4F:Dy/Sm
Fig. 2 FE-SEM Micrograph NaMgSO4F: Dy/Sm
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Fig. 3 PL Excitation spectra monitored at em 574 nm and Emission spectra monitored at ex 363 nm of NaMgSO4F:Dy
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Fig. 4 PL Excitation spectra monitored at em 598 nm and Emission spectra
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Fig. 5 PL Excitation (em = 598 nm) and Emission spectra of (ex = 363 nm) of NaMgSO4F:Dy, Sm phosphor with variation in Sm concentration
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Fig. 6 Energy transfer scheme Dy (4F9/2) Sm (4G5/2) in NaMgSO4F: Dy/Sm Phosphor
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Fig. 7 Decay curves of Different Conc. of Dopants in NaMgSO4F: Dy (0.05
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Fig. 8 CIE Co-ordinates [a, b, c] of NaMgSO4F:Dy3+/Sm3+
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