Site-selective occupation, optical spectrum regulation and photoluminescence property investigation of Eu2+-activated blue light-excited yellow-orange emitting phosphors

We report yellow-orange emitting phosphors Sr9−xCaxMg1.5(PO4)7:0.05Eu2+ (SCxMPO:Eu2+, x = 0.5–2.5) and Sr9−yBayMg1.5(PO4)7:0.05Eu2+ (SByMPO:Eu2+, y = 0.5–3.0) with broad emission bands (450–800 nm). All these phosphors can be excited efficiently by blue light and n-UV light. Their crystal structure,...

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Published in:Physical chemistry chemical physics : PCCP 2023-04, Vol.25 (14), p.9987-9998
Main Authors: Sun, Wenzhi, Zhao, Tingting, Wang, Shuya, Denghu Wei, Jiao, Mengmeng, Zhang, Hongwu
Format: Article
Language:English
Subjects:
Calcium ions
Cerium
Crystal structure
Dipoles
Doping
Emission
Europium
Light emitting diodes
Optical properties
Phosphors
Photoluminescence
Quadrupole interaction
Quadrupoles
Spectra
Thermal stability
Ultraviolet radiation
White light
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Summary:We report yellow-orange emitting phosphors Sr9−xCaxMg1.5(PO4)7:0.05Eu2+ (SCxMPO:Eu2+, x = 0.5–2.5) and Sr9−yBayMg1.5(PO4)7:0.05Eu2+ (SByMPO:Eu2+, y = 0.5–3.0) with broad emission bands (450–800 nm). All these phosphors can be excited efficiently by blue light and n-UV light. Their crystal structure, photoluminescence spectra, fluorescence decay curves and thermal stability were investigated in detail. As doping concentrations of Ca2+ or Ba2+ increase, Eu2+ emitting centers will selectively occupy different Sr2+ sites, thus leading to the regulation of optical spectra of SCxMPO:Eu2+ and SByMPO:Eu2+. Accordingly, the emission colors of SCxMPO:Eu2+ and SByMPO:Eu2+ samples can gradually turn from yellow to orange when excited using 460 nm blue light. And the emission colors of a given sample can also be varied under different excitations because there are three kinds of emitting centers in SCxMPO:Eu2+ and SByMPO:Eu2+. In addition, introducing Ca2+ and Ba2+ can enhance the thermal stability of the phosphors obviously, and overall, the thermal stability of SByMPO:Eu2+ is better than that of SCxMPO:Eu2+. We chose SB2.5MPO:zEu2+ as an example to further investigate its photoluminescence properties, and found that the optimal doping concentration of Eu2+ is 0.08, and dipole–quadrupole interaction is dominated in the concentration quenching mechanism. Furthermore, high-quality warm white light can be obtained by two ways: (a) 470 nm blue LED chip + SC1.5MPO:Eu2+ [CCT = 3639 K, Ra = 82.21] and (b) 470 nm blue LED chip + SB2.5MPO:Eu2+ and YAG:Ce3+ [CCT = 4284 K, Ra = 86.69]. The excellent performances indicate that SCxMPO:Eu2+ and SByMPO:Eu2+ are attractive candidates for warm WLEDs.
ISSN:1463-9076
1463-9084
DOI:10.1039/d3cp00456b