• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.640-643
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• 2004

We have synthesized SrS:Eu red phosphor by solid state method and investigated to adopt a red phosphor for LEDs. The SrS:Eu phosphor shows broad emission band at 600nm region due to f-d energy transfer of $Eu^{2{\cdot}}$. Our results show that the SrS:Eu red phosphor exhibits the better luminescence efficiency than that of the industrially available product SrS:Eu phosphor.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1512-1514
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• 2007

Long afterglow $SrAl_2O_4:Eu^{2+}$,$Dy^{3+}$ is synthesized by a solid state reaction. The effect of flux $B_2O_3$ on the sintering dynamic process, the optimum concentrations of $Eu^{2+}$ and $Dy^{3+}$ for long lasting bright luminescence property and the effect of charge compensators like $Mg^{2+}$, $Zn^{2+}$, $Na^+$, $K^+$ on long persistence have been investigated.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1537-1538
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• 2007

ZnS:Cu,Cl phosphor was synthesized by solid-liquid state reaction with two firing steps. Each stage of the process was carefully monitored so that the final product was comparable to commercially-available phosphor. The effect of $Cu^{2+}-doping$ concentration has been investigated on the luminescence characteristics of ZnS:Cu,Cl blue-green phosphors for inorganic electroluminescent device.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.10a
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• pp.22-25
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• 2006

Long lasting phosphor materials are in great demand for their applications in the area of light emitting diodes (LEDs), commercial displays and warning signals. After glow longevity, brightness, photo-resistance and chemical and environment stability are most important qualities that are desired for these materials. Alumina as host lattice with various rare earth elements has been found to be good at the same time inexpensive material for the synthesis of the phosphor materials. This communication explored the effect of mixed rare earth metal on the luminescence properties of these materials for the first time. Various permutations and combinations of $Sr^{2+}$ and $Ba^{2+}$ have been investigated in order to achieve robust and high luminescence characteristics in the tailored phosphor materials.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.576-577
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• 2008

ZnS:Cu,Cl blue-green phosphors were prepared by conventional solid state reaction. Copper activator of different concentrations was doped into ZnS structure at two firing steps. The luminescence characteristics dependent on $Cu^{2+}$ doping concentration of the phosphors has been investigated for inorganic electroluminescent device.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1514-1517
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• 2005

The $(Y,Gd)BO_3:Eu^{3+}$ phosphor was made by coprecipitation method. The precipitated powders were amorphous. The value of pH in the process of coprecipitation was critical for the luminescence of phosphors. The particle size and morphology were influenced by pH value. The lower calcination temperature and hydrothermal synthesis leads to the distortion of lattices. The distorted lattices changed the symmetry of $Eu^{3+}$ site. The broken inversion symmetry in the distorted lattice caused the increased emission of $^5D_0{\rightarrow}^7D_2$ transition.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1013-1016
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• 2003

A new route for the synthesis of silver doped of zinc sulfide phosphor by combustion method has been investigated. Silver nitrate was decomposed with urea or carbohydrazide to give small size particles in presence of alkali metal halides at low temperature compared to the conventional method. The high temperature inherent to the highly exothermic nature of redox reaction leads to well-crystallized powder in short time. The phosphors thus obtained were further heated at $1050^{\circ}C$ in an inert atmosphere for 3hrs to get better luminescence properties.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1009-1012
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• 2003

A novel powder processing technique for the preparation of copper activated zinc sulfide (ZnS:Cu,Al) phosphor by combustion process has been proposed. Exothermic reaction between dissolved copper nitrate and carbohydrazide give small-sized particles in presence of alkali metal halides at lower temperature than the traditional method of preparation. This new route takes less than five minutes and requires much less energy. The optical and luminescence characteristics of ZnS:Cu,Al phosphor thus prepared were found to be enhanced significantly. Carbohydrazide acted as fuel at $500^{\circ}C$ with rapid heating and then the phosphors obtained were heated at $900^{\circ}C$ in an inert atmosphere for 3hrs to get better luminescent properties.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.1065-1070
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• 2003

Controlling synthesis conditions of ZnS:Cu,Al and ZnS:Cu electroluminescent phosphors we optimized particle size, color properties and efficiency. Surface properties were studied by new method and showed correlation with luminescence as shown by the analysis of EL spectra with Fok-Alentsev method. Luminance and maintenance improvement was achieved by the electron-beam annealing due to additional decomposition of $ZnS-Cu_{2}S$ solid solution and formation of centers of blue luminescence.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.35-36
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• 2000

The luminescence behaviors of Yttrium niobate and Bi doped Yttrium niobate were investigated under UV and low voltage electron excitations and interpreted with the first-principle calculations. In the UV excitation and emission spectra of $YNbO_4$ and $YNbO_4:Bi$, we were able to separate host contribution and Bi contribution and found that the shift in emission peak to longer wavelength is mainly due to Bi contribution. Using density functional theory, the cluster calculations were carried out for both $YNbO_4$ and $YNbO_4:Bi$. From the calculated density of states, we were also able to explain the charge transfer gap in the host and the effect of Bi in the excitation and emission spectra theoretically.