Photoluminescence characteristics of Sm3+-doped Ba2CaWO6 as new orange–red emitting phosphors

doi:10.1016/j.jlumin.2014.01.074

Journal of Luminescence

Volume 152, August 2014, Pages 133-137

https://doi.org/10.1016/j.jlumin.2014.01.074 Get rights and content

Highlights

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A new host-sensitized Sm³⁺-doped Ba₂CaWO₆ phosphor was firstly synthesized.
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Its structure, luminescent properties are well studied and characterized.
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There exists an efficient energy transfer from WO₆⁶⁻ group to Sm³⁺.
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The thermal quenching properties of Ba₂CaWO₆:Sm³⁺ was firstly evaluated.

Abstract

The orange–red emitting Ba₂CaWO₆:xSm³⁺ (0.01≤x≤0.25) phosphors were synthesized via solid state reaction process. The crystal structure of the phosphor was characterized by XRD. The photoluminescence excitation and emission spectra, concentration effect were investigated. The results show an efficient energy transfer from WO₆⁶⁻ group to Sm³⁺ occurs. The emission spectra of the Ba₂CaWO₆:Sm³⁺ phosphors consisted of some sharp emission peaks of Sm³⁺ ions centre at 579 nm, 618 nm, 625 nm, and 675 nm. The strongest one is located at 610 nm due to ⁴G_5/2→⁶H_7/2 transition of Sm³⁺, generating bright orange–red light. The optimum dopant concentration of Sm³⁺ ions in Ba₂CaWO₆:xSm³⁺ is around 5 mol% and the critical transfer distance of Sm³⁺ is calculated as 18 Å. The fluorescence lifetime of Sm³⁺ in Ba₂CaWO₆:0.05Sm³⁺ is 2.36 ms. The Ba₂CaWO₆:Sm³⁺ phosphors may be potentially used as orange–red phosphors for white light-emitting diodes.

Introduction

Inorganic luminescent materials have practical applications in almost all devices for artificial light production, especially in white light-emitting diodes (LEDs) illumination. Phosphor-converted white light-emitting diodes (PC-WLEDs) are the crucial developments of solid-state lighting, high efficiency and environmental safety [1], [2], [3]. To date, the most popular commercial PC-WLED is combination of a blue LED with a yellow phosphor. This type of white light has poor color render index (CRI) caused by the absence of red composition. It is also possible to use nitride phosphor blends to improve the CRI of PC-WLEDs. While nitride phosphors have the drawback of a relatively high manufacturing expense due to the severe synthesis conditions and high patent licensing costs. These problems can be resolved through the fabrication of WLEDs with tricolor (red, green, and blue) phosphors excited by a near-ultraviolet (UV) InGaN chips [4], [5], [6], [7]. However, the commercially applicable red phosphor of Y₂O₂S:Eu³⁺ is chemically unstable (releasing of hydrogen sulfide gas) and its fluorescent efficiency is lower than that of the blue (BaMgAl₁₀O₁₇:Eu²⁺) and green-emitting (ZnS:Cu⁺, Al³⁺) phosphors. Therefore, the investigations of new efficient red phosphors for W-LEDs have gained much attention.

It has been reported that Mo(W)O₄–Mo(W)O₆ groups can absorb near-UV and violet light efficiently [8], [9]. Compared with the W(Mo)O₄ groups, the octahedral-coordinated W(Mo)O₆ groups could efficiently absorb violet light and transfer the excitation energy to the activator [10]. Recently, a series of host sensitized, Eu³⁺ ion-activated double perovskite system A₂^IIB^IIM^VIO₆ (A₂BMO₆):Eu³⁺ (A=Ba, Sr; B=Ca; M=Mo and W) phosphors were investigated [11], [12], [13], [14], [15]. These molybdate and tungstate phosphors have an efficient absorption band covering the wide ultraviolet range and extending to visible light range (200–450 nm), which mainly arises from the charge transfer (CT) transition of Mo(W)O₆ groups. The emission intensity of Eu³⁺-doped Sr₂CaMoO₆ is 1.5 times higher than that of commercial Y₂O₂S:Eu³⁺ [11], and Eu³⁺-doped Sr₂Ca(Mo,W)O₆ also shows a more luminescence intensity than the commercial Y₂O₂S:Eu³⁺ under 395 nm excitation [14]. Our group [16] recently investigated the photoluminescence properties of the analogue Ba₂MgXO₆:Eu (X=W and Mo) and the energy transfer from W(Mo)O₆ groups to Eu³⁺ ions within the phosphors. The MoO₆→Eu³⁺ energy transfer efficiency could be greatly enhanced by partial substitution of Mo by W. These phosphors showed excellent color-conversion capability from near-UV to orange–red light. Compared with Eu³⁺, Sm³⁺ is an essential activator for many different inorganic lattices to produce orange–red emission because of its ⁴G_5/2→⁶H_J (J=5/2, 7/2, 9/2, and 11/2) transitions. For example, new red- or orange–red-emitting phosphors doped with Eu³⁺ ion or/and Sm³⁺ have been developed, including Gd₂MoO₆:Sm³⁺, CaWO₄:Sm³⁺ [17], [18], Sm³⁺-doped vanadate [19], [20], M₂SiO₄:Sm³⁺(M=Ba, Sr, Ca) [21], Y₂Si₄N₆C:Sm³⁺ [22], KZnGd(PO₄)₂:Eu³⁺, Sm³⁺ [23].

We noticed that the cubic double-perovskite structure Ba₂CaWO₆ have not been investigated as the Sm³⁺-activated host lattice. For understanding the wide range excitations and the energy transfers from WO₆ to Sm³⁺, we investigated the photoluminescence properties of Ba₂CaWO₆:Sm³⁺ phosphors.

Section snippets

Experimental

A series of powder samples of Ba₂Ca_1−xWO₆:xSm³⁺ (x=0.01, 0.03, 0.05, 0.08, 0.10, 0.15, and 0.20) was synthesized by a high-temperature solid-state reaction. The starting materials BaCO₃ (>99%), CaCO₃ (>99%), WO₃ (99.0%), and Sm₂O₃ (99.99%) obtained from Sigma-Aldrich were thoroughly mixed and ground in an agate mortar. The mixture was preheated at 850 °C for 24 h in a muffle furnace, reground, and finally fired at 1200 °C for 12 h in air. After reaction at 1200 °C, the products were slowly cooled

Results and discussion

Alkaline earth molybdates and tungstates of the type A₂BMO₆ (A=Ba, Sr; B=Ca; M=Mo and W) crystallize in an ordered perovskite structure related to (NH₄)₃FeF₆ and cryolite, where the B and M atoms are ordered in alternate {1 1 1} cation layers. The crystal structure diagram of double perovskite Ba₂CaWO₆ was plotted using a version of diamond (3.2) software (Fig. 1). Structurally, the compound Ba₂CaWO₆ has a cubic unit cell (a=8.392 Å) with space group $Fm \bar{3} m$ (no. 225) [24]. The Ba²⁺ ions are

Conclusions

A series of Ba₂CaWO₆:Sm³⁺ phosphors have been prepared by conventional solid-state reaction, and their structural and PL properties have been studied. The phosphor has four emission bands centered at 579 nm, 618 nm, 668 nm, and 695 nm corresponding to transitions from ⁴G_5/2 to ⁶H_5/2, ⁶H_7/2, ⁶H_9/2, and ⁶H_11/2 of Sm³⁺, respectively. The ⁴G_5/2→⁶H_7/2 (618 nm) transition has the strongest intensity. The critical quenching concentration of Sm³⁺ in Ba₂CaWO₆:Sm³⁺ phosphor is determined as 5%, and the

Acknowledgements

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (nos. 2010-0029634 and 2013012655). A Sm³⁺-doped Ba₂CaWO₆ phosphor, supplied by the Display and Lighting Phosphor Bank at Pukyong National University. This work was also supported by the National Natural Science Foundations of China (Grant no. 21201141), the Chinese Universities Scientific Fund (Grant no. QN2011119

References (44)

J. Zhang et al.
Mater. Lett.
(2012)
H. Xiao et al.
J. Alloys Compd.
(2012)
H. Li et al.
J. Alloys Compd.
(2011)
Y. Tian et al.
Mater. Res. Bull.
(2012)
H.L. Liu et al.
J. Lumin.
(2012)
J. Sun et al.
Ceram. Int.
(2013)
M.G. Brik
J. Phys. Chem. Solids
(2012)
X. Sun et al.
J. Lumin.
(2013)
J.H.G. Bode et al.
J. Lumin.
(1975)
G.S.R. Raju et al.
Spectrochim. Acta, Part A
(2008)

V. Singh et al.

J. Non-Cryst. Solids

(2010)

B.C. Jamalaiah et al.

J. Lumin.

(2009)

M.G. Ha et al.

Ceram. Int.

(2012)

G.R. Dillip et al.

J. Lumin.

(2013)

Q. Shao et al.

J. Lumin.

(2009)

S. Nakamura et al.

Appl. Phys. Lett.

(1994)

R. Mueller-Mach et al.

IEEE J. Sel. Top. Quantum Electron.

(2002)

S. Nakamura et al.

The Blue Laser Diode: Gan Based Light Emitters and Lasers

(1997)

A.A. Setlur et al.

Chem. Mater.

(2006)

R.J. Yu et al.

J. Electrochem. Soc.

(2011)

C. Guo et al.

J. Phys. D: Appl. Phys.

(2009)

H. Li et al.

J. Mater. Chem.

(2011)

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Journal of Luminescence

Highlights

Abstract

Introduction

Section snippets

Experimental

Results and discussion

Conclusions

Acknowledgements

References (44)

Mater. Lett.

J. Alloys Compd.

J. Alloys Compd.

Mater. Res. Bull.

J. Lumin.

Ceram. Int.

J. Phys. Chem. Solids

J. Lumin.

J. Lumin.

Spectrochim. Acta, Part A

J. Non-Cryst. Solids

J. Lumin.

Ceram. Int.

J. Lumin.

J. Lumin.

Appl. Phys. Lett.

IEEE J. Sel. Top. Quantum Electron.

The Blue Laser Diode: Gan Based Light Emitters and Lasers

Chem. Mater.

J. Electrochem. Soc.

J. Phys. D: Appl. Phys.

J. Mater. Chem.

Cited by (80)

Synthesis, characterization and optical tuning of Sm<sup>3+</sup> doped NaZnPO<inf>4</inf> phosphors for white LED technology

Ab-initio DFT calculations and experimental investigations into optoelectronic and structural properties of Ca<inf>9</inf>Al(PO<inf>4</inf>)<inf>7</inf>:Sm<sup>3+</sup> orange phosphor

Synthetic, structural and optical characteristic of novel color tunable reddish-orange Gd<inf>4</inf>Al<inf>2</inf>O<inf>9</inf>:Sm<sup>3+</sup> nanocrystalline materials for solid-state photonic appliances

Improving luminescence and thermometric performance of Ba<inf>2</inf>CaWO<inf>6</inf>:Er<sup>3+</sup> by tri-doping with Yb<sup>3+</sup> and Na<sup>+</sup>

Crystal structure, luminescence properties and thermal stability of novel Sr<inf>2</inf>CaLa(VO<inf>4</inf>)<inf>3</inf>: Sm<sup>3+</sup> phosphor synthesized by the combustion method

A novel high thermal stability Ba<inf>2</inf>CaWO<inf>6</inf>: Mn<sup>4+</sup> far-red emitting phosphor with a double-perovskite structure for plant growth LEDs