Influence of Dy3+ concentration on spectroscopic behaviour of Sr3MgSi2O8:Dy3+ phosphors

Journal Pre-proof Influence of Dy phosphors

3+

concentration on spectroscopic behaviour of Sr3MgSi2O8:Dy

3+

Pradeep Dewangan, D.P. Bisen, Nameeta Brahme, Shweta Sharma, Raunak Kumar Tamrakar, Ishwar Prasad Sahu, Kanchan Upadhyay PII:

S0925-8388(19)33836-8

DOI:

https://doi.org/10.1016/j.jallcom.2019.152590

Reference:

JALCOM 152590

To appear in:

Journal of Alloys and Compounds

Received Date: 20 July 2019 Revised Date:

4 October 2019

Accepted Date: 5 October 2019

Please cite this article as: P. Dewangan, D.P. Bisen, N. Brahme, S. Sharma, R.K. Tamrakar, I.P. Sahu, 3+ 3+ K. Upadhyay, Influence of Dy concentration on spectroscopic behaviour of Sr3MgSi2O8:Dy phosphors, Journal of Alloys and Compounds (2019), doi: https://doi.org/10.1016/j.jallcom.2019.152590. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2019 Published by Elsevier B.V.

1

Influence of Dy3+ concentration on spectroscopic behaviour of

2

Sr3MgSi2O8:Dy3+ phosphors

3 4

Pradeep Dewangan1*, D. P. Bisen1, Nameeta Brahme1, Shweta Sharma1, Raunak Kumar Tamrakar2, Ishwar Prasad Sahu3 and Kanchan Upadhyay4 1

5 6 7 8 9

SoS in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur, Pin-492010, Chhattisgarh, India 2 Department of Applied Physics, Bhilai Institute of Technology (Seth Balkrishan Memorial), Near Bhilai Power House, Durg, Pin-49100, Chhattisgarh, India 3 Department of Physics, Indira Gandhi National Tribal University, Amarkantak, Pin-

10

484887, Madhya Pradesh, India

11 12 13

4

International and inter University Centre of nanoscience and nanotechnology, Mahatma Gandhi university, Kottyam Pin-686560, Kerla, India *Corresponding authors: [email protected]

14

Abstract

15

White light emitting novel Sr3MgSi2O8:Dy3+ were synthesized by solid state reaction

16

(SSR) process. The structural and morphological properties were analyzed by XRD and

17

TEM. XRD pattern confirms presence of monoclinic structure with space group P121/a1.

18

Emission spectra of Sr3MgSi2O8:Dy3+ phosphors were studied as a function of Dy3+ ion

19

concentration. Emission spectra recorded at 350 nm excitation consist of characteristic

20

blue and yellow emission bands cantered at 480nm, 493 nm and 572 nm , which

21

correspond to 4F9/2→6H15/2 and 4F9/2→6H13/2 characteristic transitions of Dy3+ ions

22

respectively. Emitted colour of the phosphor was determined by CIE chromaticity

23

graph. Sr3MgSi2O8:Dy3+ phosphors are depended upon to find potential applications, for

24

instance, WLEDs and optical feature structure.

25

Keywords: Sr3MgSi2O8; XRD; Photoluminescence; CIE color co-ordinates; white light.

26 27 28

1

1

1. Introduction

2

Rare earth doped inorganic phosphors, for example, silicate based phosphor materials have

3

increased more consideration for their utilization in numerous reasonable applications in solid

4

state lighting innovation and biomedical applications due to their properties. It is connected in

5

different areas, for example, white LEDs, lighting innovation, traffic signals and numerous

6

different fields identified with lighting industry. White light producing diode is viewed as the

7

up and coming age of lighting industry because of their long lifetimes, great unwavering

8

quality and wellbeing, sparing vitality and natural amicable highlights [1–4].

9

In the present work Sr3MgSi2O8:Dy3+ phosphors were prepared by high temperature SSR

10

method. The crystal structure of the Sr3MgSi2O8 has been identified by XRD pattern and

11

corresponding lattice parameters were calculated [5]. This work reveals study of both

12

structural and spectroscopic properties of Sr3MgSi2O8:Dy3+ phosphor and conclude whether

13

this material can be applied for lighting technology and white LEDs.

14

2. Experimental

15

The Sr3MgSi2O8 phosphors with varying Dy3+ concentrations were prepared by solid

16

state reaction method. The raw materials used were strontium carbonate [SrCO3 (99.90

17

%)], magnesium oxide [MgO (99.90 %)], silicon di-oxide [SiO2 (99.99 %)] and

18

dysprosium oxide [Dy2O3 (99.99 %)]. All the chemicals used are of analytical grade

19

(A.R.) and purchased by Sigma-Aldrich. All the materials were weighed and mixed

20

thoroughly by using an agate mortar and pestle for 2h. The mixtures were then

21

transferred in to a corundum crucible and then heated at 1250ᴼC for 5h in a reducing

22

atmosphere of carbon [6, 9].

23

The crystal structure of the prepared phosphors was characterized by powder XRD

24

technique. Powder XRD patterns have been obtained from Bruker D8 advanced X-ray

25

powder diffractometer and the data were collected over the 2θ range 10º–80º. The X-

26

rays were produced using a sealed tube (CuKα) radiation source and the wavelength of

27

X-ray was 1.54060Å. The X-rays were detected using a fast counting detector based on

28

silicon strip technology (Bruker LynxEye detector). The excitation and emission spectra

29

were recorded on a Shimadzu (RF 5301-PC) spectrofluorophotometer using the Xenon

30

lamp (365nm) as an excitation source when measuring. All measurements were carried

31

out at a room temperature.

32

3. Results and discussion

2

1

3.1 Structural analysis

2

The structure and phase of prepared samples were detected by XRD investigation. The

3

XRD patterns (Fig. 1) are in great concurrence with JCPDS card no 10-0075 of pure

4

Sr3MgSi2O8, which affirms the nearness with monoclinic phase and furthermore

5

demonstrate that doping of Dy3+ ions does not roll out any change, it just adjusted the

6

crystallite estimate [8, 9]. Grid parameters and basic parameters for them are recorded

7

in Table 1a and 1b. The precious stone structure and coordination polyhedral of the

8

Sr3MgSi2O8 phosphor is exhibited in fig 2. Normal crystallite estimate was dictated by

9

utilizing Debye Scherer's condition [8]. Crystallite estimate was found around 45-60 nm for

10

variable Dy3+ doped Sr3MgSi2O8 phosphors. The XRD pattern is similar to pure Sr3MgSi2O8

11

no new peaks were observed, it confirms uniform dispersion of Dy3+ ion inside the

12

Sr3MgSi2O8 host lattice. In the phosphor MgO6 octahedral and SiO4 tetrahedron make the

13

main frame of the Sr3MgSi2O8. In lattice Mg2+ ions occupy six coordinated site whereas

14

Sr2+ ions occupy three different sites containing eight and seven coordination numbers.

15

Dy3+ ion occupy Sr3+ and Mg3+ lattice sites due to similarity in ionic radius.

16

3.2 Transmission electron microscopic analysis (TEM)

17

Crystalline behaviour and morphology of the prepared Sr3MgSi2O8:Dy3+ (2.0 mol %)

18

phosphor was further confirmed by TEM analysis as shown in Fig 3. It confirms that the

19

phosphor has crystallite size around 48 nm – 65 nm, which resembles with the XRD

20

results.

21

3.3 Photoluminescence (PL)

22

To study the optical conduct of Sr3MgSi2O8:Dy3+ phosphors, excitation and emission spectra

23

were recorded. Fig. 4(a) shows excitation range of Sr3MgSi2O8:Dy3+ (2.0 mole %) phosphor

24

and fig. 4(b) are excitation range with variable Dy3+ concentration recorded under the steady

25

emission of 480 nm. Excitation tops were gotten in ultraviolet region, situated at 326 nm, 350

26

nm, 367 nm and 388 nm. Gotten excitation tops relate to the changes from 6H15/2 ground

27

condition of the Dy3+ to its different higher energized states. The most extreme peak was

28

gotten at 350 nm relates to 6H15/2 → 6P7/2 progress, so it was picked as excitation wavelength

29

to record emission spectra.

30 31

Emission spectra of Sr3MgSi2O8:Dy3+ (2.0 mole %) phosphor is appeared in Fig.5a. Emission

32

spectrum of the phosphor was recorded under 350 nm excitation. The emission spectra has

33

intense peak at blue and yellow region centred at 480 nm, 493 nm and 572 nm separately. All 3

1

the emission peaks were compare as the function of variable Dy3+ concentration. The extreme

2

blue peak centred at 480 nm and 493 nm corresponds to the 4F9/2→ 6H15/2 and yellow

3

emission band at 572 nm compares to the 4F9/2→ 6H13/2. The 4F9/2→6H15/2 (blue) transition is

4

because of attractive dipole change, though the transition 4F9/2→6H13/2 is because of electric

5

dipole change and both relies on the synthetic condition of Dy3+ particle [9, 10]. Emission

6

spectra for variable Dy3+ concentration were recorded to decide the impact of Dy3+

7

concenration on photoluminescence behaviour. Fig 5b shows PL emission spectra of

8

Sr3MgSi2O8:XDy3+ (X = 0.5 - 4.0 mole %) phosphors under 350 nm excitation. Probable

9

energy transitions responsible for particular emission has been presented in fig 6. Fig 7 shows

10

relation between the emission intensity and Dy3+ concentration. It was discovered that the

11

emission intensity increases with increasing Dy3+ concetration up to 2.0 mole % after this

12

concentration quenching in emission intensity was observed, which is due to the

13

concentration quenching phenomenon[11]. Concetration quenching is due to the non-

14

radiative energy exchange between close-by Dy3+ particles. It relies on the basic separation

15

(Rc) between close-by particles. It was determined by utilizing the Blasse condition [12],

16

which is expressed as:

≈ 2(

17

)

(1)

18

where, Xc is the optimized concentration, N the quantity of cations in the unit cell and V the

19

volume of the unit cell (N = 4, V = 715.9Å3 for Sr3MgSi2O8, Xc = 0.02 mole %). Rc is

20

determined to be about 4Å. In present case the emission intensity per doped ion is followed

21

by the equation (3)

22 23

log = /3 log

+ log

− log

(4)

24 25

Above condition is a straight line condition. Consequently from the incline of log (I/X)

26

versus log (X) plot we can get Q esteem. Fig 8 demonstrates log (I/X) versus log (X)

27

bend. The Q esteem is determined to be 7.68 which is closer to 8. Subsequently the

28

system of energy exchanges between Dy3+ particles in Sr3MgSi2O8:Dy3+ phosphor

29

pursues the dipole-quadrupole communication.

30

3.4 CIE Chromaticity Coordinate

31

The chromaticity chart is an apparatus to indicate how the human eye will encounter light

32

with a given range. The radiance shade of the examples under the 350 nm excitation has been

4

1

portrayed by the CIE chromaticity graph [14-16] as shown in fig 9. Insets in fig 9 speak to

2

chromatic co-ordinates of Sr3MgSi2O8:Dy3+ phosphors with various Dy3+ concentrations.

3

Chromatic co-ordinates of Sr3MgSi2O8:Dy3+ phosphors are recorded in table 2, The chromatic

4

co-ordinates of the iridescence of every one of these phosphors are come to close to white

5

locale. The chromaticity outline of the CIE demonstrates the directions that are exceedingly

6

helpful in deciding the accurate discharge shading and shading virtue of an example.

7

The color purity is considered as one of the important factors for evaluating the performance

8

of phosphors, the color purity of samples has been calculated by the following equation (4)

9

[15];

10

Color purity =

11

(

) !(" " )

( #

) !("# " )

× 100%

(4)

12 13

where (x, y) and (xi, yi) are the color coordinates of the light source and the CIE equal energy

14

illuminate respectively; (xd, yd) is the chromaticity coordinate corresponding to the dominant

15

wavelength of light source, for Sr3−xMgSi2O8:xDy3+ (x= 1.0, 2.0, 3.0, 4.0 and 5.0 mol %)

16

phosphors, and the coordinates of (x, y) are (x=0.3100, y=0.3412); (x=0.3231, y=0.3525);

17

(x=0.3210, y=0.3537); (x=0.3423, y=0.3557); (x=0.3210, y=0.3537); respectively and the

18

coordinates of (xi, yi) are (0.3333,0.3333); (xd, yd) is (x=0.3110, y=0.3418); (x=0.3240,

19

y=0.3531); (x=0.3210, y=0.3537); (x=0.3410, y=0.3537);

20

corresponding to the dominant wavelength 480nm. Based on the coordinate values and

21

equation (4), we finally get the color purity of Sr3−xMgSi2O8:xDy3+ (x= 1.0, 2.0, 3.0, 4.0 and

22

5.0 mol %) phosphors as 97.87 %, 98.79 %, 99.71 %, 99.71 % and 98.75 % respectively. It is

23

worthwhile to mention that the CIE chromaticity coordinate of Sr3MgSi2O8:Dy3+ (4.0 mol%)

24

phosphor are very close to those corresponding dominant wavelength points, and that is

25

almost in white region [16].

26

Decay

27

The decay curve was recorded for Sr3MgSi2O8:Dy3+ (2.0 mole %) phosphor and plotted as

28

shown in fig 10. The curve was well fitted by a Second order exponential equation (6):

(x=0.3428, y=0.3562);

29 30

,

,

$(%) = &' exp +− . + &/ exp +− . -

(6)

31

Where, I = brightness power, A1 and A2 = constants, t = time in the wake of turning off

32

the excitation source, and τ1 and τ2 = rot times for the exponential segments speaking 5

1

to the decay rate for the quick and moderate exponential decay, individually. The

2

second order exponential decay fit might be ascribed to various conceivable outcomes;

3

(I) varieties in the convergence of dopants which emerge from their non-uniform

4

circulation in the host framework, (ii) the likelihood of non-radiative rots for lanthanide

5

particles at or close to the surface could be not quite the same as those at bigger

6

profundities of the particles and (iii) energy exchange from sensitizer to activators [17,

7

18]. Table3 demonstrates decay times for the fitted bends.

8

Conclusion

9

Sr3MgSi2O8:XDy3+ (X = 0.5, 1.0, 2.0, 3.0 and 4.0 mole %) phosphors were prepared by

10

SSRM mthod. The precious stone structure of Sr3MgSi2O8 is examined from the powder

11

XRD design by the refinement of cross section and structure parameters. The phosphors

12

can be successfully energized by 350 nm and display blue and yellow outflow groups

13

with overwhelming pinnacle found at 480 nm. The ideal doping focus is resolved to be

14

2.0 mole % for Dy3+ particles in Sr3MgSi2O8 have. The fixation extinguishing happens

15

when Dy3+ focus expanded past 2.0 mole %. The fixation extinguishing instrument can

16

be clarified by the multipolar collaboration of Dy3+ particles, and the basic exchange

17

remove (Rc) has been determined about 26å. The shading immaculateness of

18

Sr3MgSi2O8:Dy3+ (2.0 mole %) has been resolved as 99.71 %, demonstrated that

19

practically white shading is discharged by this specific phosphor. The CIE chromaticity

20

directions of Sr3MgSi2O8:Dy3+ (2.0 mole %) phosphor was determined to be ((x=0.3423,

21

y=0.3557). The rot normal for Sr3MgSi2O8:Dy3+ (2.0 mole %) phosphor is researched.

22

Rot bend was fitted by the whole of two exponential parts. Phosphor has diverse rot

23

times (τ1 = 1.01 min, τ2 = 10.15 min), they have the quick and moderate rot process.

24

The outcomes demonstrate that the Dy3+ doped phosphor Sr3MgSi2O8 could be a

25

potential possibility for the white LEDs and PDP applications.

26

Acknowledgments

27

‘‘We are very much grateful to UGC-DAE Consortium for Scientific Research, Indore (M.P.)

28

for the XRD and TEM Characterization and we are also very much thankful to Dr. Mukul

29

Gupta for his co-operation’’.

30 31

References

6

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[1] S. Ye, F. Xiao, Y. X. Pan, Y. Y. Ma, and Q. Y. Zhang, Phosphors in phosphor-converted white light-emitting diodes: Recent advances in materials, techniques and properties, Mater. Sci. Eng. Rep. 71 (2010) 1–34.

4 5

[2] Z.H. Ju, R.P. Wei, X.P. Gao, W.S. Liu and C.R. Pang, Red phosphor SrWO4:Eu3+ for potential application in white LED, Opt. Mater. 33 (2011) 909.

6 7

[3] Y.D. Huh, J.H. Shim, Y.H. Kim and Y.R. Do, Optical Properties of Three-Band White Light Emitting Diodes, J. Electrochem. Soc. 150 (2003) H57.

8 9

[4] W. Zhoua, X. Ma, M. Zhang, Luo Yi, Z. Xia, Synthesis and photoluminescence properties of green-emitting Lu3(Al,Sc)5O12:Ce3+ phosphor, Ceram. Int. 41 (2015) 7140-7145.

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[5] S. Hwangbo, Y. S. Jeon, B.A. Kang, Y.S. Kim, K.S. Hwang and J.T. Kim, Sol-gel derived blue-emitting Sr3MgSi2O8:Eu2+ oxide phosphor for ultraviolet emitting diodes, Journal of Ceramic Processing Research. 11(4) (2010) 513-515.

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[9] P. Dewangan, D. P. Bisen, N. Brahme and S. Sharma, Structural Characterization and Luminescence properties of Dy3+ Doped Ca3MgSi2O8 Phosphors, 777 (2019) 423-433.

27 28

[10] C. N. Xu, H. Yamada, X. Wang and X. G. Zheng, Strong Elasticoluminescence from monoclinic-structure SrAl2O4, Appl. Phys. Lett. 84 (2004) 3040–3042.

29 30 31

[11] C. N. Xu, X. G. Zheng, T. Wantanabe, M. Akiyama and I. Usui, Enhancement of adhesion and triboluminescence of ZnS:Mn films by annealing technique, Thin Solid Films 352 (1999) 273–278.

32

[12] G. Blasse, Energy Transfer In Oxdic Phosphors, Philips Res. Rep. 24 (1969) 131-144.

33 34 35

[13] L.G. Van Uitert, Characterization of Energy Transfer Interactions between Rare Earth Ions, J. Electochem. Soc., 114 (1967) 1048-1053.

36 37 38 39

[14] J. Suresh Kumar. K. Pavani , A. Mohan Bahu, N. Kumar Giri, S. B. Rai and L. R. Moorthy, Fluorescence characteristics of Dy3+ ions in calcium fluoroborate glasses, J. Lumin., 130 (2010) 1916-1923.

[6] P. Dewangan, D. P. Bisen N. Brahme R. K. Tamrakar S. Sharma and K. Upadhyay, Growth and synthesis of Sr3MgSi2O8:Dy3+ nanorod arrays by a SSRM, Optical and Quantum Electronics, 50 (2018) 367. [7] P. Dewangan, D. P. Bisen, N. Brahme, R. K. Tamrakar, K. Upadhyay, S. Sharma and I. P. Sahu, Studies on Thermoluminescence Properties of Alkaline Earth Silicate Phosphors, Journal of alloys and compounds, 735 (2018) 1383-1388. [8] Y. Yonesaki, T. Takei, N. Kumada and N. Kinomura, Crystal structure of Eu2+-doped M3MgSi2O8 (M: Ba, Sr, Ca) compounds and their emission properties, Solid State Chemistry. 182 (2009) 547-554.

7

1 2 3 4 5

[15] J. Zheng, Q. Cheng, W. Chen, Z. Guo and C. Chen, Luminescence Properties of an Orange-Red Ba5(BO3)2(B2O5):Sm3+ Phosphor with High Color Purity, ECS Journal of Solid State Science and Technology, 4 (5) (2015) 72-77.

6 7 8

[17] Y. Lin, Z. Zhang, Z. Tang, J. Zhang, Z. Zheng and X. Lu, The characterization and mechanism of long afterglow in alkaline earth aluminates phosphors co-doped by Eu2O3 and Dy2O3Mater Chem Phys, 70 (2001) 156–9

9 10 11

[18] P. Dorenbos, Mechanism of persistent luminescence in Sr2MgSi2O7:Eu2+; Dy3+, Phys Status Solidi B, 242 (2005) R7–9.

[16] CIE (1931) International Commission on Illumination. Publication CIE no. 15 (E-1.3.1).

Sr3MgSi2O8:Dy3+(2.0 mole %)

Intensity (a.u.)

Sr3MgSi2O8

JCPDS Card No. 10-0075

10

20

30

40

50

60

70

80

2θ θ Degree 12 13 14 15

Fig. 1 XRD patterns of Sr3MgSi2O8 and Sr3MgSi2O8:Dy3+ (2.0 mole %) phosphors

16 17 18 19

Table 1(a) Crystallographic data and refinement parameters of Sr3MgSi2O8, (b) Fractional atomic coordinates (x, y and z) and isotropic displacement (Biso, Focc.) parameters of Sr3MgSi2O8 phosphor Empirical Formula

Sr3MgSi2O8

8

Formula weight

471.33

Crystal System, Space group

Monoclinic ,P121/a1 (14)

Unit Cell Parameters

a = 13.877 Å b = 5.4577 Å c = 9.4520 Å β = 90

Volume

715.9 Å3

Z

4

Calculated density

4.37 g/cm3

Goodness of fit

2.58

Rp

9.52 %

Rwp

13.53 %

RI

2.07 %

RF

1.47 %

1

Atom

x

y

Z

Biso(Å2)

Occ

Sr1

0.2500

0.2126

0.2528

1.75

1.0

Sr2

0.0862

0.246

0.9189

1.0

1.0

Sr3

0.0889

0.741

0.4230

0.72

1.0

Mg

0.003

0.235

0.247

0.5

1.0

Si1

0.1407

0.253

0.574

0.50

1.0

Si2

0.1300

0.739

0.082

0.50

1.0

O1

0.087

0.255

0.428

0.6

1.0

O2

0.073

0.459

0.680

0.6

1.0

O3

0.085

0.999

0.655

0.6

1.0

O4

0.241

0.287

0.560

2.9

1.0

O5

0.125

0.737

0.925

0.6

1.0

O6

0.250

0.764

0.085

2.9

1.0

O7

0.107

0.462

0.181

0.6

1.0

O8

0.077

0.936

0.167

0.6

1.0

2 9

1 2

Fig. 2 Crystal structure and cation polyhedral arrangements of polymorph Sr3MgSi2O8

3

phosphor.

4 5

Fig. 3 TEM image of Sr3MgSi2O8:Dy3+ (2.0 mole %) phosphor

6 7 8

10

200 3+

Sr3MgSi2O8:Dy 175

350 nm

Intensity (a.u.)

150

367 nm 388 nm

125

326 nm

100

75

50 300

325

350

375

400

Wavelength (nm)

1 2

Fig. 4a Photoluminescence excitation (PLE) spectrum of Sr3MgSi2O8:Dy3+ (2.0 mole %)

3

under 480 nm emission

116

87

58

Intensity (a.u.)

145

29

300

320

340

360

380

400

420

Wavelength (nm)

0.5 mole % 1.0 mole % 2.0 mole % 3.0 mole % 4.0 mole %

4 5

Fig. 4b Photoluminescence excitation (PLE) spectrum of Sr3-XMgSi2O8:XDy3+ (X = 0.5, 1.0,

6

2.0, 3.0 and 4.0 mole %) under 480 nm emission

11

160

3+

Sr3MgSi2O8:Dy

480 nm

140

493 nm 572 nm

Intensity (a.u.)

120

100

80

60

40

400

450

500

550

600

650

Wavelength (nm)

1 2

Fig. 5a Photoluminescence emission (PLE) spectrum of Sr3MgSi2O8:Dy3+ (2.0 mole %) under

3

350 nm excitation

100

75

50

400

450

500

550

600

Wavelength (nm)

4 5

12

650

Intensity (a.u.)

125

0.5 mole % 1.0 mole % 2.0 mole % 3.0 mole % 4.0 mole %

1

Fig. 5b Photoluminescence emission (PLE) spectra of Sr3MgSi2O8:Dy3+ (X = 0.5, 1.0, 2.0, 3.0

2

and 4.0 mol %) under 350 nm excitation.

3

4 5

Fig. 6 Corresponding transition in the energy level of the Dy3+ ion

160

Relative Intensity(a.u.)

140 120 100 80 60 40 0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Concentration x mole %

6 7

Fig. 7 Dependence of emission intensity on Dy3+ concentration. 13

9.0 8.7

log I/x

8.4 8.1

slope = -2.56

7.8 7.5 7.2

-3.9

-3.8

-3.7

-3.6

-3.5

-3.4

-3.3

-3.2

log x

1 2

Fig. 8 The relationship between the log(I/X) and log(X) of Sr3MgSi2O8:Dy3+.

3 4

Fig. 9 The CIE chromaticity diagram for Sr3MgSi2O8:Dy3+ phosphors 14

Table 2 CIE coordinates of Sr3MgSi2O8:Dy3+smaples

1

Dy3+ Concentration

CIE Coordinates (x, y)

A

0.5 Mole %

(0.31002, 0.3412)

B

1.0 Mole %

(0.3231, 0.3525)

C

2.0 Mole %

(0.3423, 0.3557)

D

3.0 Mole %

(0.32105, 0.3537)

E

4.0 Mole %

(0.3210, 0.3537)

2 3

3+

Sr3MgSi2O8:Dy (2.0 Mole %)

8000 7000

Intensity (a.u.)

6000 5000 4000 3000 2000 1000 0 0

250

500

750

1000

1250

1500

1750

2000

2250

2500

Time (s)

4 5

Fig. 10 Decay curves of Sr3MgSi2O8:Dy3+ (2.0 mole %) phosphor

6

Table 3 Fitting results of the decay Curves Phosphor

τ1 (min)

τ2 (min)

Sr3MgSi2O8:Dy3+ (2.0 mole %)

1.01

10.15

7 8 9 10

15

Highlights: •

Sr3MgSi2O8 phosphor doped with Dy3+ synthesized by solid state reaction process

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Sr3MgSi2O8:Dy3+ phosphor is efficiently usefull in whilt light application for outdoor lighting.

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Radiated shade of the phosphor was controlled by CIE chromaticity graph.

Declaration of interests √ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

√ The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:

Dr. Pradeep Dewangan SoS in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur, Pin-492010, Chhattisgarh, India