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MORPHOLOGY AND CATHODOLUMINESCENCE OF Li-DOPED SrTiO3:Pr3+,Ga3+, A RED PHOSPHOR OPERATING AT LOW VOLTAGES Jin Young Kim, Duk Young Jeon, Seong-Gu Kang1, Seung-Youl Kang2, and Kyung-Soo Suh2 Dept. of Materials Sci. and Eng., Korea Advanced Institute of Sci. & Tech., 373-1, Kusong-dong, Yusung-gu, Taejon, 305-701, Korea 1 Dept. of Chemical Eng., Hoseo Univ., Korea 2 Electronics and Telecommunications Research Institute, Korea Abstract SrTiO3:Pr,Ga phosphor using Li2CO3 as a flux has been investigated as a red phosphor for the application to fluorescent displays operated at low voltage. In SrTiO3:Pr,Ga system, Pr3+ can substitute for Sr2+ because the ionic radius of Pr3+ almost coincides with that of Sr2+. Previous work, it was found by XRF analysis of SrTiO3:Pr,Ga single crystal that only a small fraction of Pr ions are incorporated in the SrTiO3 lattice. In the present study, the effect of Li addition into SrTiO3:Pr,Ga on the cathodoluminescence (CL) properties was examined at low acceleration voltage. Especially, thanks to the liquid phase of Li2CO3 during the sintering process, doped Li ions act as a lubricant for the efficient incorporation of Pr ions into SrTiO3:Pr,Ga lattice. Furthermore, it is found that the Li addition could enhance the generation of the characteristic emission of Pr-activated SrTiO3 phosphors. Introduction Recently, there has been a renewed interest in the development of more efficient cathodoluminescent (CL) phosphors for low voltage display applications such as field emission displays (FEDs) or vacuum fluorescent displays (VFDs) [1,2]. However, because of manufacturing and other practical constraints for low voltage display applications, the low voltage phosphors have serious concerns with respect to efficiency, spectral response, long-term reliability and stability, surface passivation, desorption, screening, and synthesis methods. Among these listed, the high CL efficiency at low voltage excitation of phosphors under the high current density of electron beam is of great technological importance. A new red-emitting low voltage phosphor, perovskite-

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structured SrTiO3:Pr,Ga or Al has been investigated for its application to display devices because of high luminous efficiency and excellent color purity that it offers [3,4]. This study attempts, by adding Li2CO3 to SrTiO3:Pr,Ga as a flux, to enhance the red Pr characteristic emission and not to deteriorate the color purity. The effect of the Li flux on the CL intensity of SrTiO3:Pr,Ga fired in air are also investigated through analysis of the phosphors’ morphologies. Experiments A single crystal of SrTiO3 containing varying concentrations of Pr and Ga was grown by a standard floating zone method. The crystal boules were cut into wafers of about 1 mm thick and polished to an optical quality by successively finer diamond abrasives. The dopant concentrations in the crystal were determined by X-ray fluorescence spectroscopy(QuanX, KevexSpectrace). The SrTiO3:Pr,Ga powder phosphor sample using Li2CO3 as the flux agent was prepared with so