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Photoluminescence and morphology of flux grown BAM phosphor using a novel synthesis method
A. Dulda,조덕수,W. J. Park,마사키타카키,윤대호 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.6
Small Eu2+ doped barium magnesium aluminate (BAM : Eu) phosphor particles with a narrow size distribution were prepared using a flux-assisted liquid phase precursor (LPP) method. XRD showed that the crystallinity of BAM particles increased significantly with an increase in the boric acid concentration, as a flux, and the firing temperature. According to FESEM, the phosphor particles produced without the flux and fired at 1450℃ had a rod type morphology, 60-100 nm in diameter and 500- 700 nm in length. The morphology of the phosphor particles transformed from a rod to a hexagonal type with a concomitant increase in the particle size (from ~1 to 2 μm) when 1, 2 and 5 wt% of boric acid was added. The photoluminescence intensity of phosphor particles was also influenced by the addition of the flux due to the enhanced particle size, crystallinity and activator ion distribution.
A. Dulda,M. K. Jung,박우정,마사키타카키,윤대호 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1
Blue emitting Eu2+ doped barium-magnesium aluminate (BAM) nano-phosphors were synthesized using liquid phase precursor (LPP) method corresponding to Ba0.87-0.90Mg0.91-1.0Al10O17-17.05: Eu0.05. The phosphor particle size, morphology and crystallinity were characterized by FESEM and X-Ray diffraction analysis. The effects of composition and particle size on the luminescence efficiency were investigated by employing photoluminescence spectroscopy. The rod shaped phosphor particles ~60 nm in diameter and 400-700 nm in length were obtained. The phosphor particles emission peaks shifted towards a longer wavelength with 80% luminescence intensity compared with the commercial BAM.
MILLING EFFECT AND ENHANCED LUMINESCENCE PROPERTY OF BAM NANOPHOSPHOR VIA SURFACE MODIFICATIONS
A. DULDA,조덕수,M. TAKAKI,D. H. YOON 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2009 NANO Vol.4 No.6
Surface modification of luminescent nanomaterials has attracted considerable technological interest. With decreasing particle size, the passivation of surface defects is of vital importance. This paper reports the effect of an alkali (KOH) solution treatment and organic functional groups on the luminescence efficiency and particle dispersibility. Fourier transform infrared spectroscopy provided clear evidence of surface modification with organic functional groups from the C=O, C–H, and C–O stretching modes at 1740, 1365, and 1218 cm-1. The KOH-treated sample showed a 40% increase in luminescence intensity, whereas 87% increase in luminescence intensity was obtained from the dispersion-agent-containing sample. To the best of our knowledge, this is the highest efficiency improvement for sub-micrometer-sized BAM:Eu2+ phosphors reported thus far.
윤대호,M. K. Jung,W. J. Park,J. W. Moon,마사키타카키,A. Dulda 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
(Yx,Gdy)O3:Eu3+1-x-y red phosphor was prepared at ring temperatures from 700 ℃ to 1400 ℃ by using liquid phase precursor methods. The particle sizes of the samples prepared at firing temperatures of 800 ℃ and 1000 ℃ were about 23 nm and 64 nm, respectively. The strongest absorption band of the samples excited at 613 nm was observed at 260 nm, which resulted from transitions toward the charge transfer state (CTS) corresponding to the `Eu3+-O2-, interactions. At intense emission peak was observed at 613 nm due to the electric dipole transition of `5D0-7F2' induced by the lack of inversion symmetry at the Eu3+ sites. We observed that the maximum emission intensity of the samples was about 82.3 % at 1400 ℃.