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Effect of Heating Rate on Thermoluminescence Glow Curves of Rare Earth Doped Y2O3 Phosphor
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 3 (2016) 4232–4235
www.materialstoday.com/proceedings
ICMRA 2016
Effect of Heating Rate on Thermoluminescence Glow Curves of Rare Earth Doped Y2O3 Phosphor Tarkeshwari Verma1 ,Sadhana Agrawall* 1Department of Physics, National Institute of Technology Raipur, Raipur-492010, India
Abstract The present paper reports effect of heating rate on thermoluminescence glow curves of rare earth doped Y2O3 phosphor. Solid state reaction method was used for synthesis of phosphor. Crystallite size and structure of phosphors were characterized by XRD and morphology by SEM and FTIR. The crystallite size is found to be 143nm. TL glow curves show, the shifting of the peaks towards the higher temperature side with increase in heating rate. © 2016 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International conference on materials research and applications-2016. Keywords: TL glow curves ,UV exposure.
1. Introduction In a past few decades, phosphor materials have become highly significant because of their wide application in various optoelectronic devices [1]. Particularly, there is a considerable interest in studies of ultrafine and nano crystalline oxide and non-oxide materials doped with rare- earth (RE) ions in terms of fundamental research[2]. Yttrium oxide (Y2O3) is an excellent choice as a host material due to its low vibrational energy, optical band transparency (0.20-8 μm), large refractive index (> 1.9), high energy band gap (5.8 eV) and high phonons frequency [3-5]. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3 and Electron configuration 4f66s2 [3-9]. It also facilitates easy rare earth ion substitution and enables luminescent characteristics of high efficiency. Samarium is a moderately hard silvery metal that readily oxidizes in air. The
* Sadhana Agrawal. Tel. 09993885860. E-mail address: [email protected] 2214-7853 © 2016 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International conference on materials research and applications-2016.
Sadhana Agrawal / Materials Today: Proceedings 3 (2016) 4232–4235
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doping of rare-earth ions to the host material enhances the luminescent properties Various methods have been used for the synthesis of phosphors .In this reports , conventional solid state reaction method is used in order to prepare Sm+3 doped Y2O3 phosphor. 2. Experimental:2.1Sample preparation: - Analytical grade Y203 (99.9%), samarium oxide (Sm203; 99.9%), were purchased from Sigma-Aldrich Corporation. Phosphors were synthesized by the solid state reaction method where Y2O3 was used as raw material for the host where as Samarium oxide (Sm203) was taken as activator. Keeping the Sm+3 concentrations in sample as 0.5, 1,1.5,2mol%, the powders were grinded in an agate mortar and pestle for about half an hour and then placed in an alumina crucible. The powders has been calcinkated at 10000C for 1 hr and then sintered at 12000C for 3 hr in a muffle furnace with a heating rate of 5 0C/min[6-9]. All the samples were again grinded into fine powder using an agate mortar and pestle about half an hour[10]. 2.2 Sample characterization The prepared phosphors were characterized by XRD using a Bruker D8 Focus XRD measuring instrument with CuKα target radiation. The morphology of the phosphors were determined by a Scanning Electron Microscopy( Zeiss Sigma VP FEG SEM Instruments, Oxford shire, UK .The Fourier transform infrared (FTIR) spectra were recorded in the wave number range 4000–400 cm-1. The Thermoluminescence studies were carried out on a TLD reader I1009 after UV exposure for 5 min. 3. Results and discussions 3.1 XRD :-Figure1 shows the XRD patterns of synthesized Y2O3:Sm+3 phosphors .The average grain size of powders is calculated by using well known Scherer formula[17].The average size calculated is ~143 nm [11,12].
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Fig. 1. (a) Figur1 : XRD pattern of Y2O3: Sm+3;
Fig 2: FTIR spectra of Y2O3:Sm+3 doped phosphor.
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Sadhana Agrawal / Materials Today: Proceedings 3 (2016) 4232–4235
3.2Fourier transform infrared spectroscopy :-Figure shows the FTIR spectra of strong peaks centered at 409-479 is due to Y-O vibration in the prepared sample. The broad peak centered at 587cm-1 is due to Sm-O vibration in the sample. All these observed peaks found together confirm the formation of Y 2O3 phosphor.. 3.3 Scanning electron microscope (SEM):- Fig. 3 shows SEM images of prepared phosphors for different resolutions. As this figures shows, the grain size of Y2O3: Sm3+ to be in the range of few microns around 200 nm.The photographs of the samples show near spherical morphology and uniform agglomeration of the sample.
Figur3 : SEM images of Y2O3:Sm+3 (0.5mol %) with different resolution 3.4 Luminescence property Thermo luminescence study of Y2O3:Sm+3:-TL is one of the possible ways to estimate the trap states of the material. The afterglow of any phosphor is generated by the detrapped carriers that recombine with the opposite carrier in the luminescent center with a transition resulting in visible region. Y 2O3:Sm+3 doped with Sm+3 with concentration ratio 0.5 to 2mol%, respectively, was used to undertake the TL measurements because we observed maximum TL signal strength at this ratio.
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Figure. 4.TL glow curve of Sm+3 doped Y203 phosphor TL glow-peak,variation with Sm+3 concentration for 5 min UV.
Sadhana Agrawal / Materials Today: Proceedings 3 (2016) 4232–4235
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Figure . 5. TL glow curve of Sm+3 doped Y203 phosphor variation with different heating rate(0C). Figure 4 shows TL glow curves for the Sm+3 doped Y203 phosphor exposed to 5 min dose of UV rays with 254 UV source. The variation of TL glow peak intensity as a function of Sm+3 concentrations was studied. It is observed that TL intensity increases linearly with Sm+3 concentrations up to 1.5 mol%. Thereafter, it decreases with increasing concentration(2 mol%.) of Sm+3 . The presence of Y rare earth ions changes the TL glow curve structure either enhancing/quenching the TL efficiency. We got the maximum peak at 142OC. Figure 5 shows the effect of heating rate on TL glow curve of Y203:Sm+3 (1.5 mol%). As the heating rate increases TL peak shift towards higher temperature side and intensity decreases, it might be due to the thermal quenching. Conclusion: Y2O3 phosphor co-doped with sm3+ phosphor powders were successfully synthesized by the high temperature solid state reaction method. In the XRD pattern shows different peaks corresponding to 2θ.Highest peak refers to the 29.540 (222,) hkl values shows the phosphor have cubic structure according to crystalline symmetry. As the heating rate increases TL peak shifts towards higher temperature side due to thermal quenching. References [1]. R.Krsmanovic, Z. Antic, M.G. Nikolic, M. Mitric, M.D. Dramicanin, Ceram. Int. 37(2011) 525 [2]. E. Zych, M. Wawrzyniak, A. Kossek, J. Trojan-Piegza, L. Kepinski, J. Alloy. Compd., 451 (2008) 591 [3]. A.Garcia-Murillo, C. Le Luyer, C. Dujardin, T. Martin, C. Garapon, C. Pedrini, J.Mugnier, Res. Bull. 31 (1996) 1013. [4] Radenka Krsmanović, Željka Antić, Barbora Bártová and Miroslav D. Dramićanin, J. Alloy. Compd., 505 (2010) 224 [5] 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. [6] T.verma,S.agrawal ,international journal of advance in research and engineering ,vol.no. 4 septmber2015. [7] T.verma,S.agrawal VikasDubey,Proceedings of National Conference on Environmental Radiation and Functional Materials (NCERFM-2015), February 28 2015. [8]. Q. Yanmin, G. Hai, J. Rare Earths 27 (2009) 406. [9]. D. L. Phan, M. H. Phan, N. Vu, T.K. Anh, S.C. Yu, Phys. Status Solidi, 201 (2004),2170 [10] V Dubey, J Kaur, S Agrawal, Research on Chemical Intermediates 41 (1) 2014, 401-408. [11]C.A. Kodaira et al. / Journal of Luminescence 127 (2007) 616–622 [12]S. Ćulubrk et al./Science of Sintering, 45 (2013)323329
ScienceDirect Materials Today: Proceedings 3 (2016) 4232–4235
www.materialstoday.com/proceedings
ICMRA 2016
Effect of Heating Rate on Thermoluminescence Glow Curves of Rare Earth Doped Y2O3 Phosphor Tarkeshwari Verma1 ,Sadhana Agrawall* 1Department of Physics, National Institute of Technology Raipur, Raipur-492010, India
Abstract The present paper reports effect of heating rate on thermoluminescence glow curves of rare earth doped Y2O3 phosphor. Solid state reaction method was used for synthesis of phosphor. Crystallite size and structure of phosphors were characterized by XRD and morphology by SEM and FTIR. The crystallite size is found to be 143nm. TL glow curves show, the shifting of the peaks towards the higher temperature side with increase in heating rate. © 2016 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International conference on materials research and applications-2016. Keywords: TL glow curves ,UV exposure.
1. Introduction In a past few decades, phosphor materials have become highly significant because of their wide application in various optoelectronic devices [1]. Particularly, there is a considerable interest in studies of ultrafine and nano crystalline oxide and non-oxide materials doped with rare- earth (RE) ions in terms of fundamental research[2]. Yttrium oxide (Y2O3) is an excellent choice as a host material due to its low vibrational energy, optical band transparency (0.20-8 μm), large refractive index (> 1.9), high energy band gap (5.8 eV) and high phonons frequency [3-5]. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3 and Electron configuration 4f66s2 [3-9]. It also facilitates easy rare earth ion substitution and enables luminescent characteristics of high efficiency. Samarium is a moderately hard silvery metal that readily oxidizes in air. The
* Sadhana Agrawal. Tel. 09993885860. E-mail address: [email protected] 2214-7853 © 2016 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of International conference on materials research and applications-2016.
Sadhana Agrawal / Materials Today: Proceedings 3 (2016) 4232–4235
4233
doping of rare-earth ions to the host material enhances the luminescent properties Various methods have been used for the synthesis of phosphors .In this reports , conventional solid state reaction method is used in order to prepare Sm+3 doped Y2O3 phosphor. 2. Experimental:2.1Sample preparation: - Analytical grade Y203 (99.9%), samarium oxide (Sm203; 99.9%), were purchased from Sigma-Aldrich Corporation. Phosphors were synthesized by the solid state reaction method where Y2O3 was used as raw material for the host where as Samarium oxide (Sm203) was taken as activator. Keeping the Sm+3 concentrations in sample as 0.5, 1,1.5,2mol%, the powders were grinded in an agate mortar and pestle for about half an hour and then placed in an alumina crucible. The powders has been calcinkated at 10000C for 1 hr and then sintered at 12000C for 3 hr in a muffle furnace with a heating rate of 5 0C/min[6-9]. All the samples were again grinded into fine powder using an agate mortar and pestle about half an hour[10]. 2.2 Sample characterization The prepared phosphors were characterized by XRD using a Bruker D8 Focus XRD measuring instrument with CuKα target radiation. The morphology of the phosphors were determined by a Scanning Electron Microscopy( Zeiss Sigma VP FEG SEM Instruments, Oxford shire, UK .The Fourier transform infrared (FTIR) spectra were recorded in the wave number range 4000–400 cm-1. The Thermoluminescence studies were carried out on a TLD reader I1009 after UV exposure for 5 min. 3. Results and discussions 3.1 XRD :-Figure1 shows the XRD patterns of synthesized Y2O3:Sm+3 phosphors .The average grain size of powders is calculated by using well known Scherer formula[17].The average size calculated is ~143 nm [11,12].
. 0.5mol% (2,2,2)
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(622)
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Fig. 1. (a) Figur1 : XRD pattern of Y2O3: Sm+3;
Fig 2: FTIR spectra of Y2O3:Sm+3 doped phosphor.
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Sadhana Agrawal / Materials Today: Proceedings 3 (2016) 4232–4235
3.2Fourier transform infrared spectroscopy :-Figure shows the FTIR spectra of strong peaks centered at 409-479 is due to Y-O vibration in the prepared sample. The broad peak centered at 587cm-1 is due to Sm-O vibration in the sample. All these observed peaks found together confirm the formation of Y 2O3 phosphor.. 3.3 Scanning electron microscope (SEM):- Fig. 3 shows SEM images of prepared phosphors for different resolutions. As this figures shows, the grain size of Y2O3: Sm3+ to be in the range of few microns around 200 nm.The photographs of the samples show near spherical morphology and uniform agglomeration of the sample.
Figur3 : SEM images of Y2O3:Sm+3 (0.5mol %) with different resolution 3.4 Luminescence property Thermo luminescence study of Y2O3:Sm+3:-TL is one of the possible ways to estimate the trap states of the material. The afterglow of any phosphor is generated by the detrapped carriers that recombine with the opposite carrier in the luminescent center with a transition resulting in visible region. Y 2O3:Sm+3 doped with Sm+3 with concentration ratio 0.5 to 2mol%, respectively, was used to undertake the TL measurements because we observed maximum TL signal strength at this ratio.
750
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1420 C
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128.30 C
550 500
Intensity
450
1320 C
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1210 C
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150
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Figure. 4.TL glow curve of Sm+3 doped Y203 phosphor TL glow-peak,variation with Sm+3 concentration for 5 min UV.
Sadhana Agrawal / Materials Today: Proceedings 3 (2016) 4232–4235
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Figure . 5. TL glow curve of Sm+3 doped Y203 phosphor variation with different heating rate(0C). Figure 4 shows TL glow curves for the Sm+3 doped Y203 phosphor exposed to 5 min dose of UV rays with 254 UV source. The variation of TL glow peak intensity as a function of Sm+3 concentrations was studied. It is observed that TL intensity increases linearly with Sm+3 concentrations up to 1.5 mol%. Thereafter, it decreases with increasing concentration(2 mol%.) of Sm+3 . The presence of Y rare earth ions changes the TL glow curve structure either enhancing/quenching the TL efficiency. We got the maximum peak at 142OC. Figure 5 shows the effect of heating rate on TL glow curve of Y203:Sm+3 (1.5 mol%). As the heating rate increases TL peak shift towards higher temperature side and intensity decreases, it might be due to the thermal quenching. Conclusion: Y2O3 phosphor co-doped with sm3+ phosphor powders were successfully synthesized by the high temperature solid state reaction method. In the XRD pattern shows different peaks corresponding to 2θ.Highest peak refers to the 29.540 (222,) hkl values shows the phosphor have cubic structure according to crystalline symmetry. As the heating rate increases TL peak shifts towards higher temperature side due to thermal quenching. References [1]. R.Krsmanovic, Z. Antic, M.G. Nikolic, M. Mitric, M.D. Dramicanin, Ceram. Int. 37(2011) 525 [2]. E. Zych, M. Wawrzyniak, A. Kossek, J. Trojan-Piegza, L. Kepinski, J. Alloy. Compd., 451 (2008) 591 [3]. A.Garcia-Murillo, C. Le Luyer, C. Dujardin, T. Martin, C. Garapon, C. Pedrini, J.Mugnier, Res. Bull. 31 (1996) 1013. [4] Radenka Krsmanović, Željka Antić, Barbora Bártová and Miroslav D. Dramićanin, J. Alloy. Compd., 505 (2010) 224 [5] 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. [6] T.verma,S.agrawal ,international journal of advance in research and engineering ,vol.no. 4 septmber2015. [7] T.verma,S.agrawal VikasDubey,Proceedings of National Conference on Environmental Radiation and Functional Materials (NCERFM-2015), February 28 2015. [8]. Q. Yanmin, G. Hai, J. Rare Earths 27 (2009) 406. [9]. D. L. Phan, M. H. Phan, N. Vu, T.K. Anh, S.C. Yu, Phys. Status Solidi, 201 (2004),2170 [10] V Dubey, J Kaur, S Agrawal, Research on Chemical Intermediates 41 (1) 2014, 401-408. [11]C.A. Kodaira et al. / Journal of Luminescence 127 (2007) 616–622 [12]S. Ćulubrk et al./Science of Sintering, 45 (2013)323329