Ceramics-Silikáty 56, (4) 295 - 300 (2012) |
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EFFECT OF ALKALINE IONS ON THE PHASE EVOLUTION, PHOTOLUMINESCENCE, AND AFTERGLOW PROPERTIES OF SrAl2O4: Eu2+, Dy3+ PHOSPHOR |
Shin Hyunho, Ullah Shafqat, Chung Kwanghyun |
Department of Materials Engineering, Gangneung-Wonju National University,
210-702 Gangneung, Gangwon, Republic of Korea
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Keywords: SrAl2O4, Afterglow, Phosphor, Alkaline ions, Defect complex |
A series of SrAl2O4: Eu2+, Dy3+ long-afterglow (LAG) phosphors with varying concentration of Li+, Na+ and K+, has been
synthesized. The increased concentration of the three types of alkaline ions does not decrease the quantity of the total
luminescent phases (SrAl2O4 plus Sr4Al14O25), but a different set of secondary phases has been evoluted for the K+-added
series due to the failure of the isncorporation of relatively large K+ (1.38 Å) to the Sr2+ (1.18 Å) site in the hosts, unlike the
cases of smaller Li+ (0.76 Å) and Na+ (1.02 Å) ions. PL excitation, PL emission, and LAG luminescence, are decreased
by all investigated alkaline ions, which would be due to the diminished incorporation of Eu2+ and Dy3+ activators into the
luminescent hosts by the alkaline ions. For the cases of the Li+ and Na+-added series, the incorporated Li+ or Na+ to the
luminescent hosts would also limit the activation of Eu2+ and charge trapping/detrapping of Dy3+ to yield the diminished PL
properties and LAG luminescence. The type of defect complex formed by the addition of Li+ and Na+ ions has been deduced
and compared with that formed when no alkaline ion is added. |
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