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Synthesis and photoluminescent properties of Dy3+ doped Y2O3 phosphor
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 4 (2017) 10474–10478
www.materialstoday.com/proceedings
ICEMS 2016
Synthesis and photoluminescent properties of Dy3+ doped Y2O3 phosphor 1
1
Tarkeshwari Verma , Shambhavi Katyayan , Sadhana Agrawal 1
1*
Department of Physics, National Institute of Technology Raipur, Raipur-492010, India
Abstract 3+
In this report, structure, morphology and luminescent studies of Y2O3:Dy phosphors prepared by solid sate reaction method are presented. With this simple and cost effective method, phosphor with desired phase composition can be obtained by mixing appropriate amounts of yttrium and dysprosium oxide. A set of samples is prepared with different Dy3+ concentrations in order to observe changes in luminescent properties. For all samples, XRD pattern showed that prepared phosphors have cubic
structure ,the crystallite size of the phosphors was calculated from the full width half maxima of the diffraction peaks by using Scherer formula equation and is approximated to be 143.1 nm . SEM analysis showed the nanocrystalline size of 110 nm. The SEM gives the agglomerated fluffy nature of prepared phosphor. FTIR confirms the characteristics vibrational mode Dy-O bonding. The variation of PL characteristics with varying concentration(0.5,1,1.5 and 2 mol%) of Dy3+ is analyzed .The optical absorption band spectra is measured in range 200 to 500 nm. © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Recent Trends in Engineering and Material Sciences (ICEMS-2016). Keywords: Photoluminescence, FTIR , XRD, UV exposure:
1.Introduction Present paper reports synthesis method and characterization of Y2O3: Dy3+ phosphors. Modern light devices play an important role in reducing the growing problems of environment and energy crises. The requirement of efficient *Corresponding Author : E-Mail id: [email protected] .
2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Recent Trends in Engineering and Material Sciences (ICEMS-2016).
Sadhana Agrawal/ Materials Today: Proceedings 4 (2017) 10474–10478
10475
optical materials forces researchers to explore novel optical material, especially rare earth doped phosphors [1–5]. The unique electronic and optical properties of rare earth ions attract researchers' attention for the development of such phosphors that are requirements of the growing technology's demand.[5,6].In this respect many of the rare earth activated host materials have been continuously investigated, but this paper mainly discuses Y2O3 based phosphors because of their self-activation, good stability to different physical conditions (chemical and thermal) and broad applicability in various field such as scintillation, solid state lasers, electro-optic applications, catalytic optical fibres etc. Moreover, Y2O3 possesses a higher melting point (2400 ◦C), higher thermal conductivity, wide transparency range (0.2 –8 ȝm) with a band gap of 5.6 eV, high refractive index (∼1.8) and low cut-off phonon energy ,While the majority(380of thecmworks−1)on nanocrystalline. Y2O3 has yellow-emitting phosphors due to its unique spectral properties and has been extensively studied in various hosts. Y2O3: Dy3+ ( 0.5,1,1.5 mol%) phosphors were prepared by the solid state reaction method. 2 .Material and methods: The appropriate amounts of the yttrium oxide( 99.99%) and dysprosium (Sigma-Aldrich, 99%) with a different concentration for the Dy3+ doped Y2O3 nano-sized powders synthesis by the solid state reaction method. TheDy3+ concentration was studied in the 0.5 to 2 mol % range with respect to the Dy3+ content. Solid state reaction method is used for sample preparation. This synthesis process consists of basically three stages first is grinding , second one is calcinations and last one is sintering. . The structural properties of samples were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM). The effects of Dy3+ concentration on the photoluminescence properties of Dy3+ doped Y2O3 phosphor were investigated by using spectro-fluorometer. The photo luminescent (PL) characteristics of the powders were measured at room temperature with a spectrofluorometer operating on the spectra mode with a ms sampling window 20 ms sampling window 0.01 ms delay time and 50 ms time per flash.
3.Results and discussions 3.1.XRD: Figure 1 shows the X-ray diffraction pattern of Dy3+ doped Y2O3 phosphors. The XRD peaks of the virgin phosphor were identified and indexed according to the JCPDS file No. 83-0927 of Y2O3 [6]Figure 1 shows that all diffraction peaks of these samples can be assigned to the pure-cubic structure (JCPDS 86-1107) because the crystal symmetry depends on the concentration of the doping ions. Particle size is143.1 nm which is calculated by using Debye-Scherer’s equation [7 -10]. 3.2 Scanning electron microscope (SEM) :- Figure 2 shows SEM images of prepared phosphors for different resolutions. As this figures shows, the grain size of Y2O3: Dy3+ to be in the range of few microns. The surface morphology is uniform. Agglomeration of few particles forms nano-particle type of structure. Some of them were found to possess spherical shape in surface morphology of prepared phosphors which shows the cubic structure and good agreement with XRD results. The photographs of the samples show near spherical morphology with average sizes of around 110 nm.
3.3Fourier Transforms Infrared Spectroscopy:- In FTIR spectra ( Figure 3), strong peaks were cantered at 409-587 cm-1 is due to Y-O vibration in the prepared sample. The broad peak cantered at 587cm-1 is due to Dy-O vibration in the sample. The FTIR spectra also confirm the formation of Y2O3 doped with Dy3+ phosphor prepared by solid state reaction method [8-12].
10476
Sadhana Agrawal/ Materials Today: Proceedings 4 (2017) 10474–10478
0 .5 m o l% (2 ,2 ,2 )
50000
40000
in te n s ity
(4 4 0 )
30000
20000
(6 2 2 )
(4 0 0 )
10000
0 0
10
20
30
40
50
60
70
2 th e ta
3+
Figure 1:XRD pattern for Y2O3: Dy
Figur2 : SEM image of Dy
3+
doped Y2O3 phosphor
3+
Figure 3: FTIR spectra of Y2O3:Dy doped phosphor.
80
90
Sadhana Agrawal/ Materials Today: Proceedings 4 (2017) 10474–10478
10477
3.4. Photo luminescence study of Y203:Dy+3 phosphor Figure 4 and 5 illustrates the photoluminescence excitation and emission spectral characteristic of the synthesized phosphor, the spectra shown corresponds to the Y2O3:Dy3+ with different concentration of Dy+3 . The excitation spectrum was measured in the 220–600 nm range for the 573 nm emission wavelength and shows several peaks located under the range 450 to 600 nm. The peak cantered at 500 nm is associated with the yttrium oxide bandto-band absorption and charge transfer to the Dy+3 ion. The peak cantered at 500 nm is attributed to the Dy3+ to O2charge-transfer band (CTB). The PL emission spectrum was obtained at an excitation wavelength of 350 nm, it exhibits four distinct emission peaks located at 581 nm, associated with the hypersensitive transition 4F9/2-6H13/2 at 484 nm corresponding to the less sensitive transition 4F9/2-6H15/2 at 667 nm corresponding to the 4F9/2-6H11/2 transition ( Fig. 5). The PL intensity was found to increase monotonically with increasing concentration of Dy3+. It is possible to observe that the best emission efficiency is associated with a dopant concentration of 2 mol%.. At higher dopant concentrations the mean distance between dopant ions is much shorter; therefore these ions can interact by an electric multiplier process leading to energy migration and to an increase of the probability of a non radiative recombination . The optimum concentration for luminescent emission of the Y2O3:Dy+3 phosphor was used in further experiments. Some emission bands are observable under 350-nm radiation due to Stokes transitions. Luminescence emission occurs from 4F9/2 level to thelower-lying states 6H13/2 (570 –590 nm) . 0.5mol% 1mol% 1.5mol% 2mol%
1200
1000
0.5mol% 1mol% 1.5mol% 2mol%
1100
581.5
1000 900 800
intensity(a.u.)
intensity(a.u.)
800
600
400
584.20 583.19 583
700 600 500 400 300 200
200
100 0
0 550
560
570
580
590
600
wavelenght(nm)
Figure 4- PL excitation spectra of Y2O3:Dy3+ doped phosphor
-100 550
555
560
565
570
575
580
585
590
595
600
wavelenght(nm)
Figure5- PL emission spectra of Y2O3:Dy3+ doped phosphor.
4. Conclusions Y2O3 phosphor co-doped with Dy3+phosphor powders was successfully synthesized by the high temperature solid state reaction method. The X ray spectra had different peaks corresponding to 2θ where the highest peak refers to the 29.30 (222,) hkl values show the phosphor have cubic structure according to crystalline symmetry. SEM image shows, the grain size of Y2O3: Dy3+is in the range of few microns .The surface morphology is uniform. The absorption band is observed around 570 cm−1 is because of characteristic metal-oxide (Y-O) stretching vibrations in cubic Y2O3.PL shows the luminescence properties depended on the dopant concentration . A strong yellow emission due to the 4F9/2-6H13/2 transition is visible with the naked eye and is expected to find applications in wide areas of light industry.
10478
Sadhana Agrawal/ Materials Today: Proceedings 4 (2017) 10474–10478
References :[1] Y. Liu, Y. Wang, L. Wang, Y. Y. Gu, S. H. Yu, Z. G. Lu andR. Sun, RSC Adv., 2014, 4, 4754. [2] A. M. Kaczmareka and R. Van Deun, Chem. Soc. Rev., 2013,42, 8835. [3] N. G. Yeh, C. H. Wu and T. C. Cheng, Renewable SustainableEnergy Rev., 2010, 14, 2161. [4 ]N. Yeh and J. P. Chung, Renewable Sustainable Energy Rev.,2009, 13, 2175. [5] K. V. Dabre*a and S. J. Dhobleb,RSC Adv., 2015, 5, 60409–60418 | 60417 [6]. R.D. Shannon, Acta Crystallogr. Sect. A 32, 751–767 (1976) [7] B. D. Cullity, Elements of X-ray Diffraction, Addison-WesleyPublishing Company, USA, 1956. [8] S Agrawal, V Dubey, 3rd international conference on fundamental and applied sciences (icfas 2014): Innovative Research in Applied Sciences for a Sustainable Future, 1621, 560-564, http://dx.doi.org/10.1063/1.4898522. [9] T.verma,S.agrawal ,international journal of advance in research and engineering ,vol.no. 4 septmber2015.[10] T.verma,S.agrawal VikasDubey,Proceedings of National Conference on Environmental Radiation and Functional Materials (NCERFM-2015), February 28 2015. [11] V Dubey, J Kaur, S Agrawal, Research on Chemical Intermediates 41 (1) 2014, 401-408 [12] Balderas-Xicohténcatl et al. / Journal of Luminescence 146 (2014) 497–501
ScienceDirect Materials Today: Proceedings 4 (2017) 10474–10478
www.materialstoday.com/proceedings
ICEMS 2016
Synthesis and photoluminescent properties of Dy3+ doped Y2O3 phosphor 1
1
Tarkeshwari Verma , Shambhavi Katyayan , Sadhana Agrawal 1
1*
Department of Physics, National Institute of Technology Raipur, Raipur-492010, India
Abstract 3+
In this report, structure, morphology and luminescent studies of Y2O3:Dy phosphors prepared by solid sate reaction method are presented. With this simple and cost effective method, phosphor with desired phase composition can be obtained by mixing appropriate amounts of yttrium and dysprosium oxide. A set of samples is prepared with different Dy3+ concentrations in order to observe changes in luminescent properties. For all samples, XRD pattern showed that prepared phosphors have cubic
structure ,the crystallite size of the phosphors was calculated from the full width half maxima of the diffraction peaks by using Scherer formula equation and is approximated to be 143.1 nm . SEM analysis showed the nanocrystalline size of 110 nm. The SEM gives the agglomerated fluffy nature of prepared phosphor. FTIR confirms the characteristics vibrational mode Dy-O bonding. The variation of PL characteristics with varying concentration(0.5,1,1.5 and 2 mol%) of Dy3+ is analyzed .The optical absorption band spectra is measured in range 200 to 500 nm. © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Recent Trends in Engineering and Material Sciences (ICEMS-2016). Keywords: Photoluminescence, FTIR , XRD, UV exposure:
1.Introduction Present paper reports synthesis method and characterization of Y2O3: Dy3+ phosphors. Modern light devices play an important role in reducing the growing problems of environment and energy crises. The requirement of efficient *Corresponding Author : E-Mail id: [email protected] .
2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International Conference on Recent Trends in Engineering and Material Sciences (ICEMS-2016).
Sadhana Agrawal/ Materials Today: Proceedings 4 (2017) 10474–10478
10475
optical materials forces researchers to explore novel optical material, especially rare earth doped phosphors [1–5]. The unique electronic and optical properties of rare earth ions attract researchers' attention for the development of such phosphors that are requirements of the growing technology's demand.[5,6].In this respect many of the rare earth activated host materials have been continuously investigated, but this paper mainly discuses Y2O3 based phosphors because of their self-activation, good stability to different physical conditions (chemical and thermal) and broad applicability in various field such as scintillation, solid state lasers, electro-optic applications, catalytic optical fibres etc. Moreover, Y2O3 possesses a higher melting point (2400 ◦C), higher thermal conductivity, wide transparency range (0.2 –8 ȝm) with a band gap of 5.6 eV, high refractive index (∼1.8) and low cut-off phonon energy ,While the majority(380of thecmworks−1)on nanocrystalline. Y2O3 has yellow-emitting phosphors due to its unique spectral properties and has been extensively studied in various hosts. Y2O3: Dy3+ ( 0.5,1,1.5 mol%) phosphors were prepared by the solid state reaction method. 2 .Material and methods: The appropriate amounts of the yttrium oxide( 99.99%) and dysprosium (Sigma-Aldrich, 99%) with a different concentration for the Dy3+ doped Y2O3 nano-sized powders synthesis by the solid state reaction method. TheDy3+ concentration was studied in the 0.5 to 2 mol % range with respect to the Dy3+ content. Solid state reaction method is used for sample preparation. This synthesis process consists of basically three stages first is grinding , second one is calcinations and last one is sintering. . The structural properties of samples were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM). The effects of Dy3+ concentration on the photoluminescence properties of Dy3+ doped Y2O3 phosphor were investigated by using spectro-fluorometer. The photo luminescent (PL) characteristics of the powders were measured at room temperature with a spectrofluorometer operating on the spectra mode with a ms sampling window 20 ms sampling window 0.01 ms delay time and 50 ms time per flash.
3.Results and discussions 3.1.XRD: Figure 1 shows the X-ray diffraction pattern of Dy3+ doped Y2O3 phosphors. The XRD peaks of the virgin phosphor were identified and indexed according to the JCPDS file No. 83-0927 of Y2O3 [6]Figure 1 shows that all diffraction peaks of these samples can be assigned to the pure-cubic structure (JCPDS 86-1107) because the crystal symmetry depends on the concentration of the doping ions. Particle size is143.1 nm which is calculated by using Debye-Scherer’s equation [7 -10]. 3.2 Scanning electron microscope (SEM) :- Figure 2 shows SEM images of prepared phosphors for different resolutions. As this figures shows, the grain size of Y2O3: Dy3+ to be in the range of few microns. The surface morphology is uniform. Agglomeration of few particles forms nano-particle type of structure. Some of them were found to possess spherical shape in surface morphology of prepared phosphors which shows the cubic structure and good agreement with XRD results. The photographs of the samples show near spherical morphology with average sizes of around 110 nm.
3.3Fourier Transforms Infrared Spectroscopy:- In FTIR spectra ( Figure 3), strong peaks were cantered at 409-587 cm-1 is due to Y-O vibration in the prepared sample. The broad peak cantered at 587cm-1 is due to Dy-O vibration in the sample. The FTIR spectra also confirm the formation of Y2O3 doped with Dy3+ phosphor prepared by solid state reaction method [8-12].
10476
Sadhana Agrawal/ Materials Today: Proceedings 4 (2017) 10474–10478
0 .5 m o l% (2 ,2 ,2 )
50000
40000
in te n s ity
(4 4 0 )
30000
20000
(6 2 2 )
(4 0 0 )
10000
0 0
10
20
30
40
50
60
70
2 th e ta
3+
Figure 1:XRD pattern for Y2O3: Dy
Figur2 : SEM image of Dy
3+
doped Y2O3 phosphor
3+
Figure 3: FTIR spectra of Y2O3:Dy doped phosphor.
80
90
Sadhana Agrawal/ Materials Today: Proceedings 4 (2017) 10474–10478
10477
3.4. Photo luminescence study of Y203:Dy+3 phosphor Figure 4 and 5 illustrates the photoluminescence excitation and emission spectral characteristic of the synthesized phosphor, the spectra shown corresponds to the Y2O3:Dy3+ with different concentration of Dy+3 . The excitation spectrum was measured in the 220–600 nm range for the 573 nm emission wavelength and shows several peaks located under the range 450 to 600 nm. The peak cantered at 500 nm is associated with the yttrium oxide bandto-band absorption and charge transfer to the Dy+3 ion. The peak cantered at 500 nm is attributed to the Dy3+ to O2charge-transfer band (CTB). The PL emission spectrum was obtained at an excitation wavelength of 350 nm, it exhibits four distinct emission peaks located at 581 nm, associated with the hypersensitive transition 4F9/2-6H13/2 at 484 nm corresponding to the less sensitive transition 4F9/2-6H15/2 at 667 nm corresponding to the 4F9/2-6H11/2 transition ( Fig. 5). The PL intensity was found to increase monotonically with increasing concentration of Dy3+. It is possible to observe that the best emission efficiency is associated with a dopant concentration of 2 mol%.. At higher dopant concentrations the mean distance between dopant ions is much shorter; therefore these ions can interact by an electric multiplier process leading to energy migration and to an increase of the probability of a non radiative recombination . The optimum concentration for luminescent emission of the Y2O3:Dy+3 phosphor was used in further experiments. Some emission bands are observable under 350-nm radiation due to Stokes transitions. Luminescence emission occurs from 4F9/2 level to thelower-lying states 6H13/2 (570 –590 nm) . 0.5mol% 1mol% 1.5mol% 2mol%
1200
1000
0.5mol% 1mol% 1.5mol% 2mol%
1100
581.5
1000 900 800
intensity(a.u.)
intensity(a.u.)
800
600
400
584.20 583.19 583
700 600 500 400 300 200
200
100 0
0 550
560
570
580
590
600
wavelenght(nm)
Figure 4- PL excitation spectra of Y2O3:Dy3+ doped phosphor
-100 550
555
560
565
570
575
580
585
590
595
600
wavelenght(nm)
Figure5- PL emission spectra of Y2O3:Dy3+ doped phosphor.
4. Conclusions Y2O3 phosphor co-doped with Dy3+phosphor powders was successfully synthesized by the high temperature solid state reaction method. The X ray spectra had different peaks corresponding to 2θ where the highest peak refers to the 29.30 (222,) hkl values show the phosphor have cubic structure according to crystalline symmetry. SEM image shows, the grain size of Y2O3: Dy3+is in the range of few microns .The surface morphology is uniform. The absorption band is observed around 570 cm−1 is because of characteristic metal-oxide (Y-O) stretching vibrations in cubic Y2O3.PL shows the luminescence properties depended on the dopant concentration . A strong yellow emission due to the 4F9/2-6H13/2 transition is visible with the naked eye and is expected to find applications in wide areas of light industry.
10478
Sadhana Agrawal/ Materials Today: Proceedings 4 (2017) 10474–10478
References :[1] Y. Liu, Y. Wang, L. Wang, Y. Y. Gu, S. H. Yu, Z. G. Lu andR. Sun, RSC Adv., 2014, 4, 4754. [2] A. M. Kaczmareka and R. Van Deun, Chem. Soc. Rev., 2013,42, 8835. [3] N. G. Yeh, C. H. Wu and T. C. Cheng, Renewable SustainableEnergy Rev., 2010, 14, 2161. [4 ]N. Yeh and J. P. Chung, Renewable Sustainable Energy Rev.,2009, 13, 2175. [5] K. V. Dabre*a and S. J. Dhobleb,RSC Adv., 2015, 5, 60409–60418 | 60417 [6]. R.D. Shannon, Acta Crystallogr. Sect. A 32, 751–767 (1976) [7] B. D. Cullity, Elements of X-ray Diffraction, Addison-WesleyPublishing Company, USA, 1956. [8] S Agrawal, V Dubey, 3rd international conference on fundamental and applied sciences (icfas 2014): Innovative Research in Applied Sciences for a Sustainable Future, 1621, 560-564, http://dx.doi.org/10.1063/1.4898522. [9] T.verma,S.agrawal ,international journal of advance in research and engineering ,vol.no. 4 septmber2015.[10] T.verma,S.agrawal VikasDubey,Proceedings of National Conference on Environmental Radiation and Functional Materials (NCERFM-2015), February 28 2015. [11] V Dubey, J Kaur, S Agrawal, Research on Chemical Intermediates 41 (1) 2014, 401-408 [12] Balderas-Xicohténcatl et al. / Journal of Luminescence 146 (2014) 497–501