- Email: [email protected]
OSL MCaPO4:Ce (M = Li, k) phosphor for radiation dosimetry
Accepted Manuscript Title: A novel TL/OSL MCaPO4 : Ce (M=Li, Ka) phosphor for radiation dosimetry Author: C.B. Palan S.K. Omanwar PII: DOI: Reference:
S0030-4026(16)30390-4 http://dx.doi.org/doi:10.1016/j.ijleo.2016.04.117 IJLEO 57600
To appear in: Received date: Accepted date:
3-3-2016 20-4-2016
Please cite this article as: C.B.Palan, S.K.Omanwar, A novel TL/OSL MCaPO4: Ce (M=Li, Ka) phosphor for radiation dosimetry, Optik - International Journal for Light and Electron Optics http://dx.doi.org/10.1016/j.ijleo.2016.04.117 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.
A novel TL/OSL MCaPO4: Ce (M=Li, Ka) phosphor for radiation dosimetry C.B.Palan, S.K.Omanwar Department of Physics, Sant Gadge Baba Amravati University, Amravati, India * (Corresponding author email: [email protected])
Abstract The polycrystaline MCaPO4:Ce (M=Li, Ka) phosphors were synthesiszed via solid state method. Structural properties of prepared MCaPO4:Ce (M=Li, Ka) phosphors are confirmed by X-ray diffraction (XRD). The optical properties were characterized by use of photoluminescence (PL), thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques. The XRD pattern of MCaPO4:Ce (M=Li, Ka) phosphor fully matched with the Internatonal center for diffaction data (ICDD) file with card no 01-079-1396 and 00-0331002. The PL excitation spectra consists broad band in range 200-350 nm and maximum intensity observed at 313 nm and emission spectra consist broad in range 325-500 nm and maximum intensity observed at 381 nm. The TL glow curve of MCaPO4:Ce (M=Li, Ka) phosphors were consist overlapping peaks in temperature 50-350°C and these peaks were deconvoluted by using peak fit software. The kinetic parameters such as activation energy, frequency factor and order of kinetic were calculated by using peak shape method. Also MCaPO4:Ce (M=Li, Ka) phosphors show excellent OSL response under β irradiation. Keywords: MCaPO4:Ce (M=Li, Ka) phosphors; kinetic parameter; TL/OSL; ICDD. 1. Introduction The common approach for producing TL/OSL phosphor has been to use a for radiation dosimetry applications [1]. Recently, rare earths doped phosphate based phosphors are widely used in radiation dosimetry applications because, of their low cost synthesis methods, low effective atomic number and PL properties of these phosphors are suitable for TL/OSL reader. As compare to TL technique, OSL is appropriate technique in radiation
dosimetry fields because their advantages such as faster and multiple readouts are possible in measurements, high sensitivity, avoid thermal quenching and possible use of phosphor in plastic binders [2, 3]. The MCaPO4:RE (M=Li, Na and K & RE= Ce, Tb and Eu) phosphors are widely used for solid state lighting applications. Zubar et al. reported NaCaPO4:Eu phosphor for White LightEmitting Diode (WLED) applications [4]. Li et al. developed NaCaPO4:Mn phosphor for field emission displays [5]. More et al. reported LiCaPO4:Cu/Eu phosphor for TL dosimetry [6]. Hu et al. reported KCaPO4:Eu/Mn phosphor for solid state lighting [7]. Also RE doped ABPO4 phosphors are widely applicable in solid state lighting, PDP display and radiation dosimetry fields [7-11]. In the present report we developed MCaPO4:Ce (M=Li, Ka) phosphor via solid state reaction for radiation dosimetry applications. However, to the best of our knowledge, there are no reports on the comparative studies of PL/TL/OSL properties of MCaPO4:Ce (M=Li, Ka) phosphor. 2. Experimental details The MCaPO4:Ce (M=Li, Ka) phosphors were synthesized by using solid state method. High purity starting materials lithium nitrates (LiNO3.3H2O), potassium nitrates (KNO3), calcium nitrates (Ca(NO3)2), ammonium dihyrogen orthophosphate (NH4H2PO4) and cerium nitrates (Ce(NO3)3+HNO3) were used. Phase purity of MCaPO4:Ce (M=Li, Ka) phosphor were checked by means of X-ray powder diffraction (PXRD) using a Rigaku miniflex II diffractometer with Cu Ka (λ = 1.5405 Å) operated at 5 kV. The data were collected in a 2θ range from 10 to 70°. Irradiations of all the samples were performed at room temperature using a calibrated
90
Sr/90Y beta source in-
housed in RISO TL/OSL Reader (DA-15 Model). All TL/OSL measurements were carried out using an automatic Risø TL/OSL-DA-15 reader system at RPAD BARC (Mumbai). The PL and PL excitation (PLE) spectra were measured on (Hitachi F-7000) fluorescence spectrophotometer with a 450W xenon lamp, in the range 200–500 nm, with spectral slit width of 1 nm and PMT voltage 700V at room temperature. 3. Results and discussions 3.1 XRD-Pattern The XRD pattern of the as synthesised MCaPO4:Ce (M=Li, Ka) phosphors were represent in Fig. 1. The XRD patterns were fully matched with the Internatonal center for diffaction data (ICDD) file with card no 01-079-1396 and 00-033-1002. The comparing them, the position and intensity of the main peaks are the same and no impurity lines were observed. The structure of KCaPO4:Ce phosphor was hexagonal system with space group P-3m1(164) and lattice parameters a = 5.5085, b = 5.5085, c = 7.5020 and α = β =90, γ = 120 while the structure of LiCaPO4:Ce phosphor was hexagonal system with space group P-3m1(164) and lattice parameters a = 5.5085, b = 5.5085, c = 7.5020 and α = β =90, γ = 120. However, in MCaPO4:Ce (M=Li, Ka) lattice, the ionic radius of Ce (1.01Å) ion was nearer to that of K (1.38Å) ion than that of Li3+ (0.76 Å) ion for six fold coordination. Based on the effective ionic radii it was assumed that the k was more preferably replaced by Ce. The Miller indices of MCaPO4:Ce (M=Li, Ka) phosphors were calculated by using equation reported by Tamrakar et al.[12] and given in Table 1. 3.2 Photoluminescence (PL) Fig. 2 shows the PL excitation and emission spectra of MCaPO4:Ce (M=Li, Ka) phosphor. The excitation and emission spectra of MCaPO4:Ce (M=Li, Ka) phosphor were observed at
381 and 313 nm respectively. From same figure the excitation spectra consists broad band in range 200-350 nm and maximum intensity observed at 313 nm. The emission spectra consist broad in range 325-500 nm and maximum intensity observed at 381 nm correspond to 5d-4f (2F5/2) transitions of Ce [13]. Also observed that PL sensitivity of KCaPO4:Ce phosphor was more than PL sensitivity of LiCaPO4:Ce phosphor. 3.3 Thermoluminescence Properties The TL measurement MCaPO4:Ce (M=Li, Ka) phosphor was irradiated 100mGy of β irradiation. The TL glow curve of MCaPO4:Ce (M=Li, Ka) phosphor was shown in Fig.3. The TL sensitivity of KCaPO4:Ce phosphor was compared with TL sensitivity of LiCaPO4:Ce phosphor and TL sensitivity of KCaPO4:Ce phosphor was found to be 15 time sensitive than that of LiCaPO4:Ce phosphor. The TL glow curves of MCaPO4:Ce (M=Li, Ka) phosphors were consist overlapping peaks in temperature range 50-350°C and these peaks were deconvoluted and deconvoluted TL glow curve of MCaPO4:Ce (M=Li, Ka) phosphor as show in Fig.4. The TL glow curve of LiCaPO4: Ce phosphor consist two peaks and first peak (P1) was appeared at 123°C and second peak (P2) at 191°C. In KCaPO4:Ce phosphor TL glow curve consist two overlapping peaks and first peak (P1) was appeared at 133°C and second peak (P2) at 191°C. From Fig.4 TL second peak in MCaPO4:Ce (M=Li, Ka) phosphor is near 100-350°C, hence these peaks are dosimetric peak. The kinetics parameters such as activation energy, frequency factor and order of kinetic were calculated by using peak shape method [13,14]. The calculated kinetics parameters were as given in Table 2.
3.3 Optically simulated luminescence (OSL) Continuous wave OSL (CW-OSL) curves of MCaPO4:Ce (M=Li, Ka) phosphor as shown in Fig. 5. The wavelength of stimulation light source is 470 nm. The phosphors of equal mass in powder form were first irradiated to in (90Sr/90Y) β sources for 100mGy. The OSL sensitivities were compared with two different methods. In the first method, the OSL during the first second was compared. In the second method, the total area under OSL curve was used [15]. From Fig.5 observed that second method was fail to compared the OSL sensitivity of MCaPO4:Ce (M=Li, Ka) phosphor. Because total area under CW-OSL curve of MCaPO4:Ce (M=Li, Ka) phosphors are same. From Fig. 5 observed that OSL sensitivity of KCaPO4:Ce phosphor was 9 time than that of LiCaPO4:Ce phosphor. Conclusions The polycrystalline MCaPO4:Ce (M=Li, Ka) phosphors were successfully synthesized via solid state method. The prepared phosphors showed excellent TL/OSL properties under β irradiation. In PL, TL and OSL mode KCaPO4:Ce phosphor was more sensitive than that of LiCaPO4:Ce phosphor. Because in MCaPO4:Ce (M=Li, Ka) lattice, the ionic radius of Ce (1.01Å) ion was nearer to that of K (1.38Å) ion than that of Li3+ (0.76 Å) ion for six fold coordination. Based on the effective ionic radii it was assumed that the K was more preferably replaced by Ce ion. The TL glow curve consist overlapping peaks in temperature range 50-350°C and these peaks deconvoluted and calculated kinetic parameters by using peak shape method. The OSL sensitivity of KCaPO4:Ce phosphor was 9 time more than that of LiCaPO4:Ce phosphor. The prepared MCaPO4:Ce (M=Li, Ka) phosphors are can promising candidate for radiation dosimetry applications. Acknowledgement
One of the authors CBP is very much thankful to Head, RPAD, Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai-400085, India for providing the necessary facilities for the analysis of OSL and TL results. References [1] C.B. Palan, N.S. Bajaj, S.K. Omanwar, Mater. Res. Bull. 76 (2016) 216. [2] M. Kumar, B. Dhabekar, S.N. Menon, M.P. Chougaonkar, Y.S. Mayya Nucl Instrum. Methods Phys. Res. B 269 (2011) 1849. [3] C. B. Palan, N. S. Bajaj, S. K. Omanwar St. Petersburg Polytechnical University Journal: Physics and Mathematics 1 (2015) 410. [4] E. V. Zubar, B. I. Zadneprovskii, N. P. Efryushina, V. P. Dotsenko Russ. J. Appl. Chem. 84 (2011) 1483. [5] G. Li, X. Xu, C. Peng, M. Shang, D. Geng, Z. Cheng, J. Chen, J. Lin Opt. Express 19 (2011) 16423. [6] S.D. More, M.N. Meshram, S.P. Wankhede, P.L. Muthal, S.M. Dhopte, S.V. Moharil Physica B 406 (2011) 1178. [7] J. Hu, H. Xie, Y. Huang, D. Wei, H. J. Seo Appl. Phys. B 114 (2014) 461. [8] C.C. Lin, Z.R. Xiao, G.Y. Guo, T.S. Chan, R.S. Liu, J. Am. Chem. Soc. 132 (2010) 302. [9] C.B. Palan, N.S. Bajaj, D.K. Koul, S.K. Omanwar Int. J. Lumin. Appl. 5 (2015) 12. [10] N.S. Bajaj, C.B. Palan, K.A. Koparkar, M.S. Kulkarni, S.K. Omanwar J.Lumin. 175 (2016) 9. [11] C.B. Palan, N.S. Bajaj, A. Soni, M.S. Kulkarni, S.K. Omanwar Bull. Mater. Sci. 38 (2015) 1527. [12] R. Tamrakar Res Chem Intermed (2012) DOI 10.1007/s11164-012-0940-z. [13] C. B. Palan, K.A. Koparkar, N.S. Bajaj, S.K. Omanwar Materials Letters 175 (2016) 288. [14] C.B. Palan, N.S. Bajaj, A. Soni, S.K. Omanwar J. Lumin. 176 (2016) 106. [15] B. Dhabekar, S.N. Menon, E. Alagu Raja, A.K. Bakshi, A.K. Singh, M.P. Chougaonkar, Y.S. Mayya Nucl Instrum. Methods Phys. Res. B 269 (2011) 1844.
Counts
30000
KaCaPO4:Ce
15000
LiCaPO4:Ce
0 10
20
30
40
50
60
70
2θ
Fig. 1 XRD patterns of MCaPO4:Ce (M=Li, Ka) phosphor with ICDD file.
(1) KCaPO4 :Ce Excitation (2) KCaPO4 :Ce Emission (3) LiCaPO4 :Ce Excitation (4) LiCaPO4 :Ce Excitation
Excitation Emission
1200
(1)
(2)
PL Intensity (a.u.)
1000
800
600
400 (4)
(3)
200
0 200
250
300
350
400
450
500
Wavelength (nm)
Fig.2 Excitation and Emission spectra of MCaPO4:Ce (M=Li, Ka) phosphor
KcaPO4:Ce
5
3x10
TL Intensity (a.u.)
15 x LiCaPO4:Ce
5
2x10
5
1x10
0 0
50
100
150
200
250
300
350
400
450
ο
Temperature ( C)
Fig. 3 TL glow curve of MCaPO4:Ce (M=Li, Ka) phosphor under β irradiation.
KCaPO4 :Ce 5
3x10
TL Intensity (a.u.)
P2 5
2x10
P1
5
1x10
0 0
100
200
300
400
o
Temperature ( C)
LiCaPO4 :Ce 4
TL Intensity (a.u.)
1.0x10
P2 P1
3
5.0x10
0.0 0
100
200
300
400
ο
Temperature ( C)
Fig. 4TL deconvolution curve of MCaPO4:Ce (M=Li, Ka) phosphor.
KCaPO4:Ce
5
7.50x10
OSL Intensity (a.u.)
9 x LiCaPO4:Ce
5
5.00x10
5
2.50x10
0.00 0
10
20
30
40
50
60
Time (sec)
Fig.5. CW-OSL responses of MCaPO4:Ce (M=Li, Ka) phosphor under β irradiation
Table 1 Miller indices value MCaPO4:Ce (M=Li, Ka) phosphor
2θ
θ
Sin2 θ
Sin2 θ/ Sin2 θmin
(Sin2 θ/ Sin2 θmin) * 3
h2+k2+l2
hkl
30.46 32.66 39.84 45.2 58.1 58.14 58.16 58.26 59.72 13.62
15.23 16.33 19.92 22.6 29.05 29.07 29.08 29.13 29.86 6.81
0.0690 0.0790 0.1160 0.1476 0.2357 0.2360 0.2362 0.2369 0.2478 0.014
1 1.144 1.6811 2.1391 3.4159 3.4202 3.4231 3.4333 3.5913 1
3 3.43 5.04 6.41 10.24 10.26 10.26 10.3 10.77 3
3 3 5 6 10 10 10 10 11 3
111 111 210 211 310 310 310 310 311 111
17..82
8.91
0.023
1.642
4.928
5
210
22.52
11.26
0.038
2.7142
8.1428
8
220
23.66
11.83
0.042
3
9
9
300
27.4
13.7
0.056
4
12
12
222
29.78
14.89
0.066
4.7142
14.14286
14
321
31.16
15.58
0.072
5.1428
15.4285
16
400
32.88
16.44 0.0800
5.7142
17.14286
17
410
34.46
17.23 0.0877
6.2642
18.7928
19
331
42.64
21.32 0.1321
9.4357
28.30714
29
432
45.86
22.93 0.1517
10.8357
32.50714
32
440
48.4
24.2
12
36
36
600
59.64
29.82 0.2472
17.65
52.97143
53
720
Phosphors
KCaPO4:Ce
LiCaPO4:Ce
0.1680
Table 2 kinetics parameters of MCaPO4:Ce (M=Li, Ka) phosphor Phosphor
KCaPO4: Ce
LiCaPO4: Ce
Activation energy (eV)
Frequency factor(s-1)
Peak Temp (Tm) (0C)
µg
Order of kinetics
P1
0.534
6.3x105
133
0.49
Second
P2
0.860
2.68 x108
199
0.48
Second
P1
0.610
1.02 x107
123
0.50
Second
Peaks
P2
0.554
1.20 x105
191
0.50
Second
S0030-4026(16)30390-4 http://dx.doi.org/doi:10.1016/j.ijleo.2016.04.117 IJLEO 57600
To appear in: Received date: Accepted date:
3-3-2016 20-4-2016
Please cite this article as: C.B.Palan, S.K.Omanwar, A novel TL/OSL MCaPO4: Ce (M=Li, Ka) phosphor for radiation dosimetry, Optik - International Journal for Light and Electron Optics http://dx.doi.org/10.1016/j.ijleo.2016.04.117 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.
A novel TL/OSL MCaPO4: Ce (M=Li, Ka) phosphor for radiation dosimetry C.B.Palan, S.K.Omanwar Department of Physics, Sant Gadge Baba Amravati University, Amravati, India * (Corresponding author email: [email protected])
Abstract The polycrystaline MCaPO4:Ce (M=Li, Ka) phosphors were synthesiszed via solid state method. Structural properties of prepared MCaPO4:Ce (M=Li, Ka) phosphors are confirmed by X-ray diffraction (XRD). The optical properties were characterized by use of photoluminescence (PL), thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques. The XRD pattern of MCaPO4:Ce (M=Li, Ka) phosphor fully matched with the Internatonal center for diffaction data (ICDD) file with card no 01-079-1396 and 00-0331002. The PL excitation spectra consists broad band in range 200-350 nm and maximum intensity observed at 313 nm and emission spectra consist broad in range 325-500 nm and maximum intensity observed at 381 nm. The TL glow curve of MCaPO4:Ce (M=Li, Ka) phosphors were consist overlapping peaks in temperature 50-350°C and these peaks were deconvoluted by using peak fit software. The kinetic parameters such as activation energy, frequency factor and order of kinetic were calculated by using peak shape method. Also MCaPO4:Ce (M=Li, Ka) phosphors show excellent OSL response under β irradiation. Keywords: MCaPO4:Ce (M=Li, Ka) phosphors; kinetic parameter; TL/OSL; ICDD. 1. Introduction The common approach for producing TL/OSL phosphor has been to use a for radiation dosimetry applications [1]. Recently, rare earths doped phosphate based phosphors are widely used in radiation dosimetry applications because, of their low cost synthesis methods, low effective atomic number and PL properties of these phosphors are suitable for TL/OSL reader. As compare to TL technique, OSL is appropriate technique in radiation
dosimetry fields because their advantages such as faster and multiple readouts are possible in measurements, high sensitivity, avoid thermal quenching and possible use of phosphor in plastic binders [2, 3]. The MCaPO4:RE (M=Li, Na and K & RE= Ce, Tb and Eu) phosphors are widely used for solid state lighting applications. Zubar et al. reported NaCaPO4:Eu phosphor for White LightEmitting Diode (WLED) applications [4]. Li et al. developed NaCaPO4:Mn phosphor for field emission displays [5]. More et al. reported LiCaPO4:Cu/Eu phosphor for TL dosimetry [6]. Hu et al. reported KCaPO4:Eu/Mn phosphor for solid state lighting [7]. Also RE doped ABPO4 phosphors are widely applicable in solid state lighting, PDP display and radiation dosimetry fields [7-11]. In the present report we developed MCaPO4:Ce (M=Li, Ka) phosphor via solid state reaction for radiation dosimetry applications. However, to the best of our knowledge, there are no reports on the comparative studies of PL/TL/OSL properties of MCaPO4:Ce (M=Li, Ka) phosphor. 2. Experimental details The MCaPO4:Ce (M=Li, Ka) phosphors were synthesized by using solid state method. High purity starting materials lithium nitrates (LiNO3.3H2O), potassium nitrates (KNO3), calcium nitrates (Ca(NO3)2), ammonium dihyrogen orthophosphate (NH4H2PO4) and cerium nitrates (Ce(NO3)3+HNO3) were used. Phase purity of MCaPO4:Ce (M=Li, Ka) phosphor were checked by means of X-ray powder diffraction (PXRD) using a Rigaku miniflex II diffractometer with Cu Ka (λ = 1.5405 Å) operated at 5 kV. The data were collected in a 2θ range from 10 to 70°. Irradiations of all the samples were performed at room temperature using a calibrated
90
Sr/90Y beta source in-
housed in RISO TL/OSL Reader (DA-15 Model). All TL/OSL measurements were carried out using an automatic Risø TL/OSL-DA-15 reader system at RPAD BARC (Mumbai). The PL and PL excitation (PLE) spectra were measured on (Hitachi F-7000) fluorescence spectrophotometer with a 450W xenon lamp, in the range 200–500 nm, with spectral slit width of 1 nm and PMT voltage 700V at room temperature. 3. Results and discussions 3.1 XRD-Pattern The XRD pattern of the as synthesised MCaPO4:Ce (M=Li, Ka) phosphors were represent in Fig. 1. The XRD patterns were fully matched with the Internatonal center for diffaction data (ICDD) file with card no 01-079-1396 and 00-033-1002. The comparing them, the position and intensity of the main peaks are the same and no impurity lines were observed. The structure of KCaPO4:Ce phosphor was hexagonal system with space group P-3m1(164) and lattice parameters a = 5.5085, b = 5.5085, c = 7.5020 and α = β =90, γ = 120 while the structure of LiCaPO4:Ce phosphor was hexagonal system with space group P-3m1(164) and lattice parameters a = 5.5085, b = 5.5085, c = 7.5020 and α = β =90, γ = 120. However, in MCaPO4:Ce (M=Li, Ka) lattice, the ionic radius of Ce (1.01Å) ion was nearer to that of K (1.38Å) ion than that of Li3+ (0.76 Å) ion for six fold coordination. Based on the effective ionic radii it was assumed that the k was more preferably replaced by Ce. The Miller indices of MCaPO4:Ce (M=Li, Ka) phosphors were calculated by using equation reported by Tamrakar et al.[12] and given in Table 1. 3.2 Photoluminescence (PL) Fig. 2 shows the PL excitation and emission spectra of MCaPO4:Ce (M=Li, Ka) phosphor. The excitation and emission spectra of MCaPO4:Ce (M=Li, Ka) phosphor were observed at
381 and 313 nm respectively. From same figure the excitation spectra consists broad band in range 200-350 nm and maximum intensity observed at 313 nm. The emission spectra consist broad in range 325-500 nm and maximum intensity observed at 381 nm correspond to 5d-4f (2F5/2) transitions of Ce [13]. Also observed that PL sensitivity of KCaPO4:Ce phosphor was more than PL sensitivity of LiCaPO4:Ce phosphor. 3.3 Thermoluminescence Properties The TL measurement MCaPO4:Ce (M=Li, Ka) phosphor was irradiated 100mGy of β irradiation. The TL glow curve of MCaPO4:Ce (M=Li, Ka) phosphor was shown in Fig.3. The TL sensitivity of KCaPO4:Ce phosphor was compared with TL sensitivity of LiCaPO4:Ce phosphor and TL sensitivity of KCaPO4:Ce phosphor was found to be 15 time sensitive than that of LiCaPO4:Ce phosphor. The TL glow curves of MCaPO4:Ce (M=Li, Ka) phosphors were consist overlapping peaks in temperature range 50-350°C and these peaks were deconvoluted and deconvoluted TL glow curve of MCaPO4:Ce (M=Li, Ka) phosphor as show in Fig.4. The TL glow curve of LiCaPO4: Ce phosphor consist two peaks and first peak (P1) was appeared at 123°C and second peak (P2) at 191°C. In KCaPO4:Ce phosphor TL glow curve consist two overlapping peaks and first peak (P1) was appeared at 133°C and second peak (P2) at 191°C. From Fig.4 TL second peak in MCaPO4:Ce (M=Li, Ka) phosphor is near 100-350°C, hence these peaks are dosimetric peak. The kinetics parameters such as activation energy, frequency factor and order of kinetic were calculated by using peak shape method [13,14]. The calculated kinetics parameters were as given in Table 2.
3.3 Optically simulated luminescence (OSL) Continuous wave OSL (CW-OSL) curves of MCaPO4:Ce (M=Li, Ka) phosphor as shown in Fig. 5. The wavelength of stimulation light source is 470 nm. The phosphors of equal mass in powder form were first irradiated to in (90Sr/90Y) β sources for 100mGy. The OSL sensitivities were compared with two different methods. In the first method, the OSL during the first second was compared. In the second method, the total area under OSL curve was used [15]. From Fig.5 observed that second method was fail to compared the OSL sensitivity of MCaPO4:Ce (M=Li, Ka) phosphor. Because total area under CW-OSL curve of MCaPO4:Ce (M=Li, Ka) phosphors are same. From Fig. 5 observed that OSL sensitivity of KCaPO4:Ce phosphor was 9 time than that of LiCaPO4:Ce phosphor. Conclusions The polycrystalline MCaPO4:Ce (M=Li, Ka) phosphors were successfully synthesized via solid state method. The prepared phosphors showed excellent TL/OSL properties under β irradiation. In PL, TL and OSL mode KCaPO4:Ce phosphor was more sensitive than that of LiCaPO4:Ce phosphor. Because in MCaPO4:Ce (M=Li, Ka) lattice, the ionic radius of Ce (1.01Å) ion was nearer to that of K (1.38Å) ion than that of Li3+ (0.76 Å) ion for six fold coordination. Based on the effective ionic radii it was assumed that the K was more preferably replaced by Ce ion. The TL glow curve consist overlapping peaks in temperature range 50-350°C and these peaks deconvoluted and calculated kinetic parameters by using peak shape method. The OSL sensitivity of KCaPO4:Ce phosphor was 9 time more than that of LiCaPO4:Ce phosphor. The prepared MCaPO4:Ce (M=Li, Ka) phosphors are can promising candidate for radiation dosimetry applications. Acknowledgement
One of the authors CBP is very much thankful to Head, RPAD, Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai-400085, India for providing the necessary facilities for the analysis of OSL and TL results. References [1] C.B. Palan, N.S. Bajaj, S.K. Omanwar, Mater. Res. Bull. 76 (2016) 216. [2] M. Kumar, B. Dhabekar, S.N. Menon, M.P. Chougaonkar, Y.S. Mayya Nucl Instrum. Methods Phys. Res. B 269 (2011) 1849. [3] C. B. Palan, N. S. Bajaj, S. K. Omanwar St. Petersburg Polytechnical University Journal: Physics and Mathematics 1 (2015) 410. [4] E. V. Zubar, B. I. Zadneprovskii, N. P. Efryushina, V. P. Dotsenko Russ. J. Appl. Chem. 84 (2011) 1483. [5] G. Li, X. Xu, C. Peng, M. Shang, D. Geng, Z. Cheng, J. Chen, J. Lin Opt. Express 19 (2011) 16423. [6] S.D. More, M.N. Meshram, S.P. Wankhede, P.L. Muthal, S.M. Dhopte, S.V. Moharil Physica B 406 (2011) 1178. [7] J. Hu, H. Xie, Y. Huang, D. Wei, H. J. Seo Appl. Phys. B 114 (2014) 461. [8] C.C. Lin, Z.R. Xiao, G.Y. Guo, T.S. Chan, R.S. Liu, J. Am. Chem. Soc. 132 (2010) 302. [9] C.B. Palan, N.S. Bajaj, D.K. Koul, S.K. Omanwar Int. J. Lumin. Appl. 5 (2015) 12. [10] N.S. Bajaj, C.B. Palan, K.A. Koparkar, M.S. Kulkarni, S.K. Omanwar J.Lumin. 175 (2016) 9. [11] C.B. Palan, N.S. Bajaj, A. Soni, M.S. Kulkarni, S.K. Omanwar Bull. Mater. Sci. 38 (2015) 1527. [12] R. Tamrakar Res Chem Intermed (2012) DOI 10.1007/s11164-012-0940-z. [13] C. B. Palan, K.A. Koparkar, N.S. Bajaj, S.K. Omanwar Materials Letters 175 (2016) 288. [14] C.B. Palan, N.S. Bajaj, A. Soni, S.K. Omanwar J. Lumin. 176 (2016) 106. [15] B. Dhabekar, S.N. Menon, E. Alagu Raja, A.K. Bakshi, A.K. Singh, M.P. Chougaonkar, Y.S. Mayya Nucl Instrum. Methods Phys. Res. B 269 (2011) 1844.
Counts
30000
KaCaPO4:Ce
15000
LiCaPO4:Ce
0 10
20
30
40
50
60
70
2θ
Fig. 1 XRD patterns of MCaPO4:Ce (M=Li, Ka) phosphor with ICDD file.
(1) KCaPO4 :Ce Excitation (2) KCaPO4 :Ce Emission (3) LiCaPO4 :Ce Excitation (4) LiCaPO4 :Ce Excitation
Excitation Emission
1200
(1)
(2)
PL Intensity (a.u.)
1000
800
600
400 (4)
(3)
200
0 200
250
300
350
400
450
500
Wavelength (nm)
Fig.2 Excitation and Emission spectra of MCaPO4:Ce (M=Li, Ka) phosphor
KcaPO4:Ce
5
3x10
TL Intensity (a.u.)
15 x LiCaPO4:Ce
5
2x10
5
1x10
0 0
50
100
150
200
250
300
350
400
450
ο
Temperature ( C)
Fig. 3 TL glow curve of MCaPO4:Ce (M=Li, Ka) phosphor under β irradiation.
KCaPO4 :Ce 5
3x10
TL Intensity (a.u.)
P2 5
2x10
P1
5
1x10
0 0
100
200
300
400
o
Temperature ( C)
LiCaPO4 :Ce 4
TL Intensity (a.u.)
1.0x10
P2 P1
3
5.0x10
0.0 0
100
200
300
400
ο
Temperature ( C)
Fig. 4TL deconvolution curve of MCaPO4:Ce (M=Li, Ka) phosphor.
KCaPO4:Ce
5
7.50x10
OSL Intensity (a.u.)
9 x LiCaPO4:Ce
5
5.00x10
5
2.50x10
0.00 0
10
20
30
40
50
60
Time (sec)
Fig.5. CW-OSL responses of MCaPO4:Ce (M=Li, Ka) phosphor under β irradiation
Table 1 Miller indices value MCaPO4:Ce (M=Li, Ka) phosphor
2θ
θ
Sin2 θ
Sin2 θ/ Sin2 θmin
(Sin2 θ/ Sin2 θmin) * 3
h2+k2+l2
hkl
30.46 32.66 39.84 45.2 58.1 58.14 58.16 58.26 59.72 13.62
15.23 16.33 19.92 22.6 29.05 29.07 29.08 29.13 29.86 6.81
0.0690 0.0790 0.1160 0.1476 0.2357 0.2360 0.2362 0.2369 0.2478 0.014
1 1.144 1.6811 2.1391 3.4159 3.4202 3.4231 3.4333 3.5913 1
3 3.43 5.04 6.41 10.24 10.26 10.26 10.3 10.77 3
3 3 5 6 10 10 10 10 11 3
111 111 210 211 310 310 310 310 311 111
17..82
8.91
0.023
1.642
4.928
5
210
22.52
11.26
0.038
2.7142
8.1428
8
220
23.66
11.83
0.042
3
9
9
300
27.4
13.7
0.056
4
12
12
222
29.78
14.89
0.066
4.7142
14.14286
14
321
31.16
15.58
0.072
5.1428
15.4285
16
400
32.88
16.44 0.0800
5.7142
17.14286
17
410
34.46
17.23 0.0877
6.2642
18.7928
19
331
42.64
21.32 0.1321
9.4357
28.30714
29
432
45.86
22.93 0.1517
10.8357
32.50714
32
440
48.4
24.2
12
36
36
600
59.64
29.82 0.2472
17.65
52.97143
53
720
Phosphors
KCaPO4:Ce
LiCaPO4:Ce
0.1680
Table 2 kinetics parameters of MCaPO4:Ce (M=Li, Ka) phosphor Phosphor
KCaPO4: Ce
LiCaPO4: Ce
Activation energy (eV)
Frequency factor(s-1)
Peak Temp (Tm) (0C)
µg
Order of kinetics
P1
0.534
6.3x105
133
0.49
Second
P2
0.860
2.68 x108
199
0.48
Second
P1
0.610
1.02 x107
123
0.50
Second
Peaks
P2
0.554
1.20 x105
191
0.50
Second