title: Effect of Composition and Impurities on the Phosphorescence of Green-Emitting Alkaline Earth Aluminate Phosphor.
abstract: Recent improvements to SrAl2O4:Eu2+, Dy3+ phosphors have enabled the use of luminescent hosts with a stable crystal structure and high physical and chemical stability, thus overcoming the bottleneck in the applicability of ZnS:Cu phosphors. However, enhancement of afterglow lifetime and brightness in SrAl2O4:Eu2+, Dy3+ phosphors remains a challenging task. Here, we have improved the afterglow characteristics in terms of persistence time and brightness by a systematic investigation of the composition of Eu-doped alkaline earth aluminate SrAl2O4:Eu2+, Dy3+ crystals. We found that a Dy3+/Eu2+ ratio of ~2.4 and ~0.935 mol Eu2+ (per mol of SrAl2O4) gave the brightest and longest emissions (11% and 9% increase for each). Doping with Si4+ also resulted in a slight increase in brightness up to ~15%. Doping with alkali metal or alkaline earth metal significantly enhanced the phosphorescence intensity. In particular, doping with 0.005 mol Li+ (per mol of SrAl2O4) alone boosted the phosphorescence intensity to 239% of the initial value, as compared to that observed for the non-doped crystal, while doping with 0.01 mol Mg2+ and 0.005 mol Li+ (per 1 mol SrAl2O4) boosted the phosphorescence intensity up to 313% of the initial value. The results of this investigation are expected to act as a guideline for the synthesis of bright and long persistent phosphors, and facilitate the development of persistent phosphors with afterglow characteristics superior to those of conventional phosphors.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States of America.
authors.forename: Doory
authors.initials: D
authors.lastname: Kim
authors.affiliation: Gwangju Institute of Science and Technology, Gwangju, South Korea.
authors.forename: Han-Eol
authors.initials: HE
authors.lastname: Kim
authors.affiliation: Korea Institute of Science and Technology, Seoul, South Korea.
authors.forename: Chang-Hong
authors.initials: CH
authors.lastname: Kim
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D003460:Crystallization; D004419:Dysprosium / Q000737:chemistry*; D005063:Europium / Q000737:chemistry*; D007700:Kinetics; D008094:Lithium / Q000737:chemistry; D049449:Luminescence; D049408:Luminescent Agents / Q000737:chemistry*; D008163:Luminescent Measurements / Q000379:methods; D008274:Magnesium / Q000737:chemistry; D012825:Silicon / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013324:Strontium / Q000737:chemistry*; D013997:Time Factors
chemical_list: D049408:Luminescent Agents; D004419:Dysprosium; D005063:Europium; D008094:Lithium; D008274:Magnesium; D000537:Aluminum Oxide; D013324:Strontium; D012825:Silicon