Luminescence and energy transfer of a color tunable phosphor Tb3+, Eu3+ co-doped KCaY(PO4)2

doi:10.1016/j.matlet.2014.08.112

Materials Letters

Volume 137, 15 December 2014, Pages 32-35

https://doi.org/10.1016/j.matlet.2014.08.112 Get rights and content

Highlights

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A novel color tunable phosphor KCaY(PO₄)₂:Tb³⁺, Eu³⁺ is synthesized by a solid state reaction.
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The Tb³⁺→Eu³⁺ energy transfer process in KCaY(PO₄)₂ is investigated by fluorescence decay time.
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Emitting color can be tuned from green through yellow and to red by increasing Eu³⁺/Tb³⁺ ratio.

Abstract

A series of color-tunable Tb³⁺, Eu³⁺ co-doped KCaY(PO₄)₂ phosphors were synthesized by solid-state reaction for the first time. The luminescent properties and energy transfer process were investigated. Cross relaxation was proved to be responsible for Tb³⁺→Eu³⁺ energy transfer. The emitting color of phosphors can be tuned from green through yellow and finally to red with increasing Eu³⁺/Tb³⁺ ratio. The results indicate that KCaY(PO₄)₂:Tb³⁺, Eu³⁺ might be served as an UV-convertible color-tunable phosphor.

Introduction

Lanthanide (Ln³⁺) doped luminescent material is a hot topic in material science and has been widely studied in recent years. One of the interesting characteristics of Ln³⁺ ions are their sharp emissions due to 4f–4f transitions, make them possess advantages like high color purity, large Stokes shift and high luminescence quantum efficiency, which are of great importance for their possible lighting and display application [1]. Most of the recent phosphors are of single-chromatic, and combination of different phosphors is used when a multi-chromatic emission is needed. However, problems like different degradation rates and re-absorption among phosphors are inevitable. Using single-host multicolor phosphor could solve the above-mentioned problems. Besides, the realization of tunable multicolor emission under a single excitation wavelength in phosphors is beneficial for potential application in display device. The multicolor tuning of phosphors can be achieved by co-doping Ln³⁺ ion into suitable host lattice, such as Tm³⁺–Dy³⁺ [2], Tb³⁺–Eu³⁺ [3] and Tm³⁺–Dy³⁺–Eu³⁺ [4].

Phosphates are excellent hosts for luminescent materials because of their facile synthesis condition, good chemical stability and low cost. In this study, Tb³⁺, Eu³⁺ co-doped KCaY(PO₄)₂ (KCYP) phosphors were synthesized. Host structure, luminescent spectra, decay time and Tb³⁺→Eu³⁺ energy transfer process were analyzed. Under NUV excitation, KCaY(PO₄)₂:Tb³⁺, Eu³⁺ phosphors can generate color-tunable emission from green to red by changing Eu³⁺/Tb³⁺ ratio.

Section snippets

Experimental

The KCaY(PO₄)₂:Tb³⁺, Eu³⁺ phosphors of composition KCaY_(1−x−y) (PO₄)₂:xTb³⁺/yEu³⁺ (x=0.20 and y=0–0.15) were prepared by a solid-state reaction method. Stoichiometric amounts of the starting materials were mixed homogeneously in the presence of acetone using an agate mortar. The samples were preheated at 900 °C for 2 h (heating rate: 10 °C/min) and then sintered at 1250 °C for 6 h (heating rate: 6 °C/min) in air atmosphere. The X-ray diffraction (XRD) measurements were carried out on a Rigaku

Results and discussion

Fig. 1a shows the XRD patterns of representative Tb³⁺/Eu³⁺-doped KCaY(PO₄)₂ samples. Most of the diffraction peaks can be indexed to the standard card JPCDS 51-1632 (KCaY(PO₄)₂. The XRD pattern of KCaY(PO₄)₂:0.20Tb³⁺, KCaY(PO₄)₂:0.20Eu³⁺ and KCaY(PO₄)₂:0.20Tb³⁺, 0.07Eu³⁺ samples displays similar profile with a minute difference in their diffraction peak intensities. This implies that the doping of Tb³⁺/Eu³⁺ ions and the synthesis conditions do not cause obvious change in the crystal structure

Conclusion

A series of Tb³⁺, Eu³⁺ co-doped KCaY(PO₄)₂ phosphor was synthesized by solid-state reaction. The results reveal that the doped Tb³⁺/Eu³⁺ ions were effectively built into the Y³⁺ site of the KCaY(PO₄)₂ host lattice. Excitation and emission spectra confirm that Tb³⁺ can efficiently sensitize Eu³⁺ emission under UV excitation and the schematic energy transfer processes are suggested. The emission color of KCaY(PO₄)₂:Tb³⁺, Eu³⁺ phosphor could be continuously changed from green (0.361, 0.540) to red

Acknowledgment

This research was supported by Guangxi Natural Science Foundation (Grant no. 2014GXNSFBA118046), and the Scientific Research Foundation of Guangxi University (Grant No. XBZ120573).

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Fluorescent properties of a green- to red-emitting Eu³⁺, Tb³⁺ codoped amorphous calciumsilicate phosphor
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Spectroscope properties of KCaY(PO₄)₂ Eu³⁺ in vacuum ultraviolet region
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High-brightness Eu³⁺-doped Ca₃(PO₄)₂ red phosphor for NUV light-emitting diodes application
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Energy transfer based enhanced red emission intensity from (Eu³⁺, Tb³⁺) LFBCd optical glasses
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There are more references available in the full text version of this article.

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Materials Letters

Highlights

Abstract

Introduction

Section snippets

Experimental

Results and discussion

Conclusion

Acknowledgment

References (10)

Tunable single-phased white-emitting phosphors Na₃YSi₃O₉: Tm³⁺, Dy³⁺

J Lumin

Fluorescent properties of a green- to red-emitting Eu³⁺, Tb³⁺ codoped amorphous calciumsilicate phosphor

J Lumin

Spectroscope properties of KCaY(PO₄)₂ Eu³⁺ in vacuum ultraviolet region

Mater Sci Eng B

High-brightness Eu³⁺-doped Ca₃(PO₄)₂ red phosphor for NUV light-emitting diodes application

Opt Mater

Energy transfer based enhanced red emission intensity from (Eu³⁺, Tb³⁺) LFBCd optical glasses

J Lumin

Cited by (32)

Multi-color tunable luminescence of SrMoO<inf>4</inf>: Tb<sup>3+</sup>, Eu<sup>3+</sup> nanophosphors for dual-mode temperature monitoring and multi-dimensional high secure anti-counterfeiting

Photoluminescent properties of rare-earth doped perovskite calcium silicates and related systems

Realization of high-quality white light emission in single-phased α-Sr<inf>2</inf>P<inf>2</inf>O<inf>7</inf>: Dy<sup>3+</sup>, Tm<sup>3+</sup> phosphor

Design of single-component panchromatic white light emitting phosphors using co-substitution strategy to stabilize divalent ions

Investigating luminescence properties and energy transfer of Ca<inf>3</inf>(PO<inf>4</inf>)<inf>2</inf>: Dy<sup>3+</sup>/Eu<sup>3+</sup> phosphor via hydrothermal synthesis

Energy transfer and tunable luminescence properties in Y<inf>3</inf>Al<inf>2</inf>Ga<inf>3</inf>O<inf>12</inf>: Tb<sup>3+</sup>, Eu<sup>3+</sup> phosphors